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 iAGNUS and WUBDEM 
 
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 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
 LOGIN BROS. 
 
 MEDICAL BOOKS 
 1814 W. HARRISON ST. CHICAC
 
 Visual Economics, 
 
 WITH RULES FOR 
 
 ESTIMATION OF THE EARNING 
 
 ABILITY AFTER INJURIES 
 
 TO THE EYES. 
 
 BY 
 
 H. MAGNUS, Med. Dr., of Breslau, Germany, 
 
 (Professor of Ophthalmology in the University 
 of Breslau, etc., etc.,) 
 
 AND 
 
 H. V. WURDEMANN, M. D., of Milwaukee, Wis., 
 
 U. S. A., 
 
 (Professor of Ophthalmology to the Milwaukee 
 Medical College, etc., etc.) 
 
 FOR THE USE OF THE MEDICAL 
 AND LEGAL PROFESSIONS, 
 BUSINESS CORPORATIONS AND 
 INSURANCE OFFICIALS 
 
 Published by 
 
 C. FORTH, 105 Grand Avenue, Milwaukee, Wis., U. S. A. 
 
 1902.
 
 copyr;ighted, i 902, 
 
 by 
 C. PO RTH, 
 
 Milwaukee, Wisconsin.
 
 DEDICATED 
 
 to the 
 
 HON. JOSEPH V. QUARLES, 
 
 Senator of the United States of America 
 and Member of the Wisconsin Bar. 

 
 PLATE L 
 
 FOR TRANSPOSITION OF THE SCIENTIFIC STANDARD OF VISUAL 
 ACUITY INTO ECONOMIC TERMS. 
 
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 5 10 15 20 25 30 35 40 45 50 55 60 65 70 ^ 75 80 85 90 95 100 
 
 The coarse full line (I) denotes the course or curve of the Visual 
 Acuity according to the Scientific Standard, 
 
 The fine full line (II) is the Economic valuation for vocations having 
 higher visual demands, and the broken line (III) the Economic valuation 
 for lower demands. 
 
 (See text Chapter VI., § 12, and Chapter VIII., § 17.)
 
 D 
 
 PREFACE. 
 
 HE great interest and large circulation with which the original 
 edition of Magnus' work, "Leitfaden fiir Begutachtung und 
 Berechnung von Unfallsbeschadigungen der Augen," was re- 
 ceived after its publication in 1894, the legal standing which 
 this and the second edition of 1897 has achieved in Germany, the 
 fascination which the reading of the original work had for the American 
 author, and the practical use which he has made of the formulas and 
 maxims of Magnus, led him, in May, 1900, to request the permission 
 of Prof. Magnus to allow of a translation, adapted to the legal, medical 
 and economic requirements of America, to be published in this country, 
 which was cheerfully given May 11th. The American editor at first 
 made a literal translation of the work, but owing to the virgin field, as 
 yet untouched in English medical literature, and almost unthought of in 
 insurance circles, and the special demands of American law, it was 
 believed that a simple translation would not meet the requirements of 
 American and English readers. Therefore, with the consent and aid of 
 Prof. Magnus, the work has been entirely re-written by the American 
 author. The introduction and all of Chapters 1, XIX and Part 111 are 
 new. A large part of Chapter VI, i. e., that more particularly relating 
 to American railway employees, and interpolations in many places 
 throughout the text are new. The formulas and calculations are adapted 
 from those in Magnus' second edition. We are greatly indebted to 
 Dr. Howard F. Hansell. of Philadelphia, for hints and extracts from 
 his paper, "Estimation of the Amount of Injury to the Earning Capacity 
 of the Individual from Partial or Complete Loss of Vision"; likewise 
 to Dr. Frank Allport. of Chicago, for information relating to classes 
 of railway employees, and to Senator Joseph V. Quarles, of Wisconsin, 
 for assistance upon the forensic portion of the work. 
 
 The reason for the publication of Magnus' original essays was the 
 passing of a Benefit and Accident Insurance Law in 1884, in Germany, 
 which placed upon the already overburdened shoulders of the physician 
 entirely new and difficult problems. The estimation of the damage 
 from eye injuries and indemnity to be allowed therefrom had heretofore 
 only been made from a philanthropic standpoint. Zehender was the 
 first to try to give a mathematical expression to such estimations, fol-
 
 lowed later by Magnus, Groenouw and others. Magnus' calculations 
 are the only ones that are founded upon anatomical and mathematical 
 data. He called to his aid an expert mathematician, Dr. Hugo Rohr, 
 who gave valuable assistance in the compilation of the tables. Magnus' 
 methods, which have been adapted to the use of American and English- 
 speaking peoples in this edition, may be carried out in actual practice, 
 so that a method for estimation of the damage to any workingman's 
 capacity from ocular injuries and the indemnification to be given there- 
 for, may be figured in a manner just to the workman, the person respon- 
 sible for the damage, to his employer or to the casualty company. We 
 hope that this work will not only prove acceptable to the medical pro- 
 fession of America and Great Britain, but also be received with interest 
 by that of the law, by insurance companies and by corporations which 
 are responsible for pecuniary indemnification in the case of accidents to. 
 
 the eyes. 
 
 H. MAGNUS, 
 
 Breslau. 
 
 H. V. WURDEMANN. 
 Milwaukee. 
 Jan. 1, 1902.
 
 CONTENTS. 
 
 Frontispiece. Plate I, For Transposition of the Scientific Standard of 
 Visual Acuity into Economic Terms. Preface pages I and 2. 
 
 PART FIRST. 
 
 Introduction'. Legal Status of the Physician in Relation to Accident 
 Insurance and Indemnity for Accidents. — Different Methods for 
 Estimation of the Loss of Earning Ability from Ocular Accidents. 
 General Principles for Estimation of the Relaton of Ocular Injures 
 to the Earning Ability. — Conception of the Earning Ability and of 
 Injuries Thereto. — Estimation of the Damage to Economic Vision. 
 Method of Mathematical Calculation 9 
 
 Introductiox. Full Earning Ability Synonymous with Visual Earnin3 
 Ability. — ^Standard Established by. this Work for Scientific Esti- 
 mation 11-12 
 
 Chapter I. The Legal Status of the Physician in Relation to 
 Accident Insurance and Indemnity for Accidents 13 
 
 § I. The Legal Status of the Physician in the United States of 
 America and definition of Damages 13 (a). — Indemnity claims ad- 
 justed according to medical advice 13. — Expert evidence in general 
 13. — lledico-legal experts 13. — Basis of expert testimony 14. — Legal 
 measure of damages 14 (b). — Nominal damages 14. — Compensatory 
 damages 14. — Factors entering into damages 14. — Earning ability 
 only fixed factor 14. § 2. Accident Insurance in America and Es- 
 timatioti of Indemnity for Accidents to the Eyes 14.- — -Estimates 
 by American accident insurance companies arbitrarily figured 
 14 (a). — U. S. Bureau of Pensions fix rates arbitrarily 1(3 (b). 
 § 3. The German Accident Insurance Law 16 — Provisions of the 
 act 16. — Explanation of its wording 16. — Inability to follow trade 
 only considered therein 16. — Indemnification not for injury itself 
 but for impairing of earning ability 16. § 4. The Determination 
 of the Corporal and Economic Damage from Injuries belongs to the 
 Physician, Estimation of the Monetary Compensation to the Cor- 
 porations and the Courts 17 
 
 Chapter II. The Different Methods fob Estimation of Loss of 
 
 the Earning Ability from Ocular Injuries IS 
 
 § 5. Zehcnder's Formula 18. — The formula and its development 
 18. — Calculation improperly made with three eye values IS. — Nor- 
 mal man given equivalent of three eyes 19. — Formula cannot be 
 scientifically applied 19. — Zehender pioneer in mathematical est'- 
 mation 19. § 6. Groenouw's Formula 19 (a). — Explanation of 
 the fornuila and development 19. — Mathematical consideration 20 
 lb). — Contains two unknown quantities and is mathematically in- 
 solvable 20. — He forces his formula 20 (c). — Formula applied to 
 monocularism 20. — Properly used makes tlie value of vision in a 
 one-eyed man equal to nothing 20. — Its principle is improp?r 21. 
 Confounds physiologic with anatomic conditions 21. — Accordingly 
 he makes human beings with nine hypothetic eyes. — Anothfr 
 mathematical view makes a cyclops 21. — The formula is a fluctu- 
 ating equation and cannot be mathematically considered 22. 
 The fictitious values generalized by his use of the formula 22. — Tlie 
 formula cannot be iised for scientific purposes 22. § 7. The For- 
 mula of Hcddaeus 22. It is not scientifically constructed 23. His 
 high estimation for the loss of binocular vision is preposterous 23. 
 Refutation of his claims 23
 
 CONTENTS. 
 
 Chapter III. § S. General Principles for Estimation of the Ee- 
 
 LATiONS of Ocular Injuries to the Earning Ability 24 
 
 The ocular earning ability is one of the corporal functions and 
 should be measured and treated as such 25 
 
 Chapter IV. The Conception of the Earning Ability and Injuries 
 
 Thereto 23 
 
 § 9. The Meaninfi of Full Earning Abiliti/ 2o. — Composition of its 
 factors 26. — Position occupied by the ability to compete 27. — Work- 
 ing ability not synonymous with earning ability 28. — A general 
 formula for the full earning ability 28 
 
 Chapter V. § 10. Determination of the Amount of Injury to 
 THE Earning Ability According to ;Magnus 29. — Working for- 
 mula for the earning ability 2D 
 
 Chapter VI. § 11. Estimation of the Damage to Economic Vision ZO 
 
 The earning ability F of our formula 31. — The factors entering 
 into the visual act 32. — Relation of the central visual acuity to the 
 ocular working ability 32. — Relation of the visual field to economic 
 vision 32. — ^Relation of tha ocular muscles to the visual field 32. 
 Relation of the ocular muscles in monocular and binocular vision 
 to working vision 33. — Relations of these factors to each other 33. 
 Formula for binocular economic vision 33. — Formula for monocular 
 economic vision 33. § 12. Estimation of the Economic Limita- 
 tions of the Central Visual Acuity 33. — Physiologic and economic 
 limits not synonymous but vary according to business demands 34. 
 Table A — The vaiious trades and professions arranged according 
 to their visual demands 37. — Group I — Trades requiring higher 
 degrees of visvial acuity 37. — Group II — Ti-ades requiring lower de- 
 grees of visual acuity 37. — Economic visvial limitations of railway 
 employees in Germany 39. — In America 40. Table B — Scitntific 
 standard for visual acuity converted into economic terms: I. for 
 vocations demanding higher vision; II. for vocations den:anding 
 lower vision 42. — Descrij^tion of Plate I for transposing the scien- 
 tific standard of visual acuity into economic equivalents 42. § 13. 
 The Economic Limits of the Visual Field and Their Estimation. 
 Division of the visual field into three zones 43. § 14. The Econom ic 
 Relations of the Ocular Musculature and Their Estimation 44. 
 The muscles have their individual values 44 
 
 Chapter VII. § 1.5. The Me.vning and Estim.\tion of the Arility 
 
 to Compete, K of Our Formula for the Earning Ability 46 
 
 The ability to compete is composed of dift'erent elements 46. — The 
 part that is furnished by the individual himself 47. — The part that 
 depends upon his employer or environment 47. — Special estimation 
 of the ability to compete 48. — Working formula 49 
 
 Chapter VIII. The Method of C.\lculatio.\ with the Formula of 
 
 Magnus 51 
 
 § 16. What does this Formula Mean? 51. — It is th^ numerical ex- 
 pression for the normal ocular earning ability 51. — On this account 
 its mathematical estimation must be complex o2. § 17. Can Fi(j- 
 uring with the Formula Be Made More Convenient ? 52. — The fac- 
 tors of the formula may be estimated from a mathematically made 
 chart in Plate III 52. — Both algebraic estimation and the ratings 
 give the same results 53. § 18. Calculation irith the Formula 
 53. — By the use of the curves in the charts the estimation is made 
 a simple example in multiplication 56
 
 CONTENTS. 
 
 PART SECOND. 
 
 Special Consideration of Various Ocular Injuries. 
 
 Chapter IX. § 19. The Eelati\-e Importance of Disturbaxces of 
 
 THE Visual Field 58 
 
 Estimation of the various forms of visual field defects with remaining 
 normal central visual acuity 59. — Summary in table form 61. 
 § 20. Disorders of the Visual Fields Complicated by Injury to the 
 Central Visual Acuity of Different Degrees in Either Eye 62. 
 Rules for its estimation 62. — Auxiliary data for estimation of the 
 earning ability Avhere the central acuitv of both eyes is impaired 
 differently ' 63 
 
 •Chapter X. The IiiPAiRiiENT of the Earxixg Ability FROii In- 
 juries TO THE Extrinsic Ocular Muscles 65 
 
 § 21. General Remarks Regarding the Importance of Injuries to 
 the Extra-Ocular Muscles 65. — Formula for the Binocular and 
 monocular acts of vision 65. § 22. The Estimation in Paralysis 
 of the muscles Uncomplicated by Other Visual Disorders 66. — Damage 
 caused by paralysis of one rectus externus 67. — Summary of the 
 earning ability and impairment thereof in uncomplicated disorders 
 of the extrinsic ocular muscles 68. § 23. Epicritin Remarks Con- 
 cerning the Foregoing 69 
 
 Chapter XL § 24. What Action Is Necessary If the Injured 
 
 Person Has Previously Had the Use of Only One Eye? 70 
 
 Scientific and economic monocularism 70. — Mathematical estimation 
 of original monocularism 71. — Estimation of ability to compete 71. 
 Formula for earning ability in monocularism 71. — Injuries to the 
 monocular visual field 72 
 
 Chapter XII. Estimation of Accident.\l Injuries in Cases in 
 Which One or Both Eyes Did Xot Possess Before the Acci- 
 dent Si:fficient Normal Central Visual Acuity 74 
 
 § 25. The Meaning of Weak Vision from an Economic Standpoint. 
 74. § 26. Estimation of the Earning Ability in Case Weakness 
 of Vision Existed Before the Accident Which Can Be l^^umerically 
 Fixed Through a Former Functional Examination 76. — ^Modified 
 visiial acuity 76. — Division of weakness of vision into four groups 
 79. § 27. Group I. One Eye Is Xormal, the Other Originally 
 Weak-Sighted. Five examples 79. § 28. Group II. Both Eyes 
 Are Originally Equally Weak-Sighted. Four examples 81. § 29. 
 Group III. Both Eyes Are Originally Weak-Sighted to a Different 
 Degree. Four examples 82 § 30. Group IV. One Eye is Blind, 
 the Other Originally Weak-Sighted. One example 84 
 
 Chapter XIII. The Loss of One Eye Through Accident 85 
 
 § 31. Estimation of the Vision in the Case of Loss of One Eye 85. 
 Visual acuity 85. — The visual field 85. — The muscles 86. — Loss of 
 power to estimate distances, etc. 86. — Annuity for the loss of one 
 eye should only be provisional 86. § 32. Estimation of the 
 Ability to Compete After the Loss of One Eye 87. § 33. Estimation 
 of the Earning Ability Where One Eye Becomes Blind 88. Differ- 
 ent valuations in monocularism 90. — Decrease of annuity after one 
 year 91. — Revision of the older rates 91. § 34. Concerning the 
 Supposed. Greater Danger of the One-Eyed Person Becoming To- 
 tally Blind and Its Relations to Indemnity 92. Danger from
 
 CONTENTS. 
 
 atrophy of the optic nerve and ghiucoma 03. Few one-eyed per- 
 sons become blind through injury 93. — Complaints of one-eyed 
 
 persons. 
 
 93 
 
 Chapter XIV. § 35. Accidental Injuries to the Crystalline 
 
 Lens. Aphakia 94 
 
 Chapter XV. § 30. Injuries of the Eyelids, Conjunctiva and 
 
 Cornea 96 
 
 Chapter XVI. § 37. Should the Danger of Sympathetic Ophthal- 
 mitis Be Considered in Estimating the Impairment of the 
 Earning Ability 97 
 
 Chapter XVII. § 38. Injuries of the Cornea Through Foreign 
 
 Bodies 98 
 
 Chapter XVIII. § 39. Accidental Impairments of the Accommo- 
 dation 99 
 
 Chapter XIX. § 40. Common Diseases of the Eyes of Local 
 
 Origin That Impair the Earning Power 100 
 
 PART THIRD. 
 
 Chapter XX. § 41. Estimation of the Pecuniary Loss to the 
 Individual by Reason of Visual Imperfections Resulting from 
 Injuries 104 
 
 Estimation of the relation between the amount of visual acuity 
 and the loss of earning capacity 104. — The earnings of the profes- 
 sional and business man 10.5. — The earnings of the artisan 105. 
 The earnings of the laboring class 105. — Table C containing ex- 
 amples illustrating the monetary valuation of the remaining earn- 
 ing ability in the case of the average professional or busine^^s man 
 suffering from accidental loss of visual acuity figured for the five 
 decades of working life 106. — Table D. the earning ability in the 
 case of the artisan 107. — Table E. the earning ability in the case 
 of the laborer 108. — Examples 110-115. — The use of our rules and 
 tables for physicians, la\\'yers and insurance officials 115 
 
 PART FOURTH. 
 
 Tables for Estimation of Different Forms of Damage to the Visual 
 
 Earning Ability 116 
 
 One Eye Xoimal, the Other Injured but Not Blind. 
 
 Table I. Vocations with higher visual demands 117 
 
 Table II. Vacations with lower visual demands 117 
 
 One Eye Blind, the Other Weak-Sighted. 
 
 Table III. Vocations with higher visual demands 118 
 
 Table IV. Vocations with lower visual demands 118 
 
 Both Eyes Suffering Injury of Equal or Different Degrees. 
 
 Table V. Vocations with higher visual demands 119 
 
 Table VI. Vocations with lower visual demands 120 
 
 Table VII. Earning ability and its impairment in disorders of the 
 
 visual field with normal central visual acuity.... 121
 
 CONTENTS. • 
 
 Table VII (a) Ability to compete and impairment of visual fields for 
 vocations \<nih higher and lower visual demands, 
 figured separately 1"22 
 
 Earning Ahiliiy in Defects of Both Eyes xvith Equally Diminished 
 Visual Acuity. 
 
 Table VIII. Vocations with higher visual demands 123 
 
 Table IX. Vocations with lower visual demands 124 
 
 Table X. Earning ability and impairment from non-complicated 
 
 disorders of the external ocular muscles 125 
 
 Earning Abiliti/ in Complicated Paralysis of the Ocular Muscles 
 u'ith Disturbances of the Visual Acuity. 
 
 Table XI. Vocations with higher visual demands 126 
 
 Table XII. Vocations with lower visual demands 126 
 
 Earning Ability and Impairment in Disturbances of the Visual 
 Acuity in an Originally One-Eyed Person. 
 
 Table XIII. Vocations with higher visual demands 127 
 
 Table XIV. Vocations with lower visual demands 127 
 
 Table XIII (a) Earning ability and impairment if the injury of one 
 muscle has to be valued correspondingly higher, in 
 special vocations 128 
 
 Earning Ability and Impairment in Disturbances of the Visual 
 Acuity in an Originally One-Eyed Person, in a Scientific Sense. 
 
 Table XV. Vocations with higher visual demands 129 
 
 Table XVI. Vocations with lower visual demands 129 
 
 Table XVII. Earning ability and impairment in disturbances of the 
 
 visual field of an originally one-eyed person 130 
 
 Table XVIII. Of the external ocular muscles of an originally one- 
 eyed person 130 
 
 Earni7ig Ability of cwi Originally One-Eyed Person with Disturb- 
 ances of the Visual Acuity Complicated with Defects of 
 the Visual Field, in a Professional Sense. 
 
 Table XIX. Vocations with higher visual demands 131 
 
 Table XX. Vocations with lower visual demands 131 
 
 Earning Ability of an Originally One-Eyed Person with Disturb- 
 ances of the Visual Acuity and Visual Field, in a Scien- 
 tific Sense. 
 
 Table XXI. Vocations with higher visual demands 132 
 
 Table XXII. Vocations with lower visual demands 132 
 
 Bibliography 135-136 
 
 Alphabetical Index 139-144 
 
 Plate II. Jaeger test types for near vision with transposition of the 
 scientific standard into economic terms. 
 
 Plate III. Snellen test types for distant vision with transposition of 
 the scientific standard into economic terms. 
 
 Plate IV. Xormal and damaged visual fields ^^^ith economic valuations. 
 
 Plate V. Curves for valuation of the visual field, of the muscular action 
 and of the ability to compete.
 
 PART FIRST. 
 
 Introduction. Legal Status of the Physician in Relation 
 to Accident Insurance and Indemnity for Accidents. 
 Different Methods for Estimation of the Loss of Earn- 
 ing Ability from Ocular Accidents. General Prin- 
 ciples for Estimation of the Relation of Ocular Injuries 
 to the Earning Ability. Conception of the Earning 
 Ability and of Injuries thereto. Estimation of the 
 Damage to Economic Vision. Method of Mathe- 
 matical Calculation.
 
 INTRODUCTION. 
 
 As the subject of which we treat in the following pages enters 
 into the domain of legal medicine and from its technical side no 
 one in America or among English-speaking peoples has yet had the 
 temerity to exhaustively treat it, and with the exception of a brief 
 essay which the American editor as chairman (2) had arranged 
 for the Section'on Ophthalmology of the American Medical Asso- 
 ciation and which was ably given by Hansell (17), some medico- 
 legal excerpts and scraps here and there in medical journals, the 
 literature is almost entirely German; we will, therefore, be obliged 
 to deal mostly with the facts and theories that have been brought 
 forth b}^ German writers, more especially those of Magnus, the 
 status of this subject in xA.merica in the law courts with the Acci- 
 dent Insurance Companies and the United States Pension office, and 
 then take up the German Accident law, after which we will proceed 
 to the scientific estimation of the visual earning ability. 
 
 In this work we start with the supposition that the earning 
 ability for any gainful vocation requiring eye sight is practically 
 synonymous Avith the visual earning ability, and that injuries to 
 the eyes affecting the vision have a direct detrimental effect upon 
 the earning capacity of the individual (See Chap. lY., § 9, p. 26; 
 Chap. YL, § 11, p. 30; Chap. YI., § 12, p. 36). It is self-evident 
 that a totally blind person is absolutely incompetent to work at any 
 trade or in any profession which demands eye-sight, and that the 
 vast majority of blind people are not only incapable of earning 
 anything, but are a charge upon their families and upon the 
 community. But even the blind man, provided that he has had the 
 necessary education and experience, need not remain absolutely 
 idle or be perfectly dependent ; for in some vocations where the use 
 of the mental powers is the chief factor, such as banking, some mer- 
 cantile pursuits and professions where knowledge may be assimi- 
 lated through the eyes of others or by methods peculiar to the 
 blind and by the actual work being done by employees, some spe- 
 cially well placed and talented individuals may continue to be 
 economic factors. But these are exceptions, and there can be no 
 doubt that the possession of good eye-sight is the prime factor for 
 full earning abilitv for the greater majority of gainful human 
 
 2
 
 12 INTRODUCTION. 
 
 vocations, and any injury to it is usually followed by a lessening 
 of the earning ability and of the resultant compensation. We con- 
 sider that with laborers or artisans, in fact any of the so-called 
 working classes, who may by accident acquire some defect of eye- 
 sight, ranging from partial to complete blindness in one or both 
 eyes, that the effect of this visual defect upon the earning ability 
 will be identical with the percentage of the loss of eye-sight or 
 visual earning ability. 
 
 A decision of this character has not yet been reached in Ameri- 
 can courts of law, but we have no doubt that it must soon be made, 
 and when such a precedent is established, the damage to economic 
 vision will, in every case, be estimated in a scientific manner and be 
 given a prominent position in judging the amount of damages to 
 be allowed in personal damage suits, of which a considerable num- 
 ber relate to the eyes. We likewise hope that the factor of visual 
 economic damage will be sometime taken into consideration in 
 insurance circles and by the United States government in estab- 
 lishing the rates of insurance and pension annuities. We are con- 
 vinced that this factor has been estimated in the following pages 
 in a scientific manner and we confidently assert that in any given 
 case where the eyes have been injured we can figure the amount 
 of damage to the earning ability. It is fortunate that the state 
 of ophthalmic science allows of a definite estimation of the working 
 powers of the eye. This is not so in respect to other corporal func- 
 tions, for instance, the economic loss of an arm or a leg or the loss 
 of the sense of smell or of hearing certainly cannot be as exactly 
 estimated as that of the sense of sight. Upon the latter depends 
 our earning power and the others but partially and temporarily af- 
 fect it. Gainful occupations may only be followed when the sense 
 of sight and the mental faculties are unimpaired. The loss of the 
 visual powers invariably has a deleterious effect upon the calling 
 dependent upon the degree of damage and the nature of the voca- 
 tion which may be shown in dollars and cents. 
 
 The work that we present may perhaps establish a standard for 
 the use of courts of law and accident insurance companies, which 
 now have no uniform methods of estimating the value of an in- 
 dividual's sight.
 
 EXPERT EVIDENCE. 13 
 
 CHAPTER L 
 
 THE LEGAL STATUS OF THE PHYSICIAN IN RELATION TO 
 
 ACCIDENT INSURANCE AND INDEMNITY 
 
 FOR ACCIDENTS. 
 
 §1. The Legal Status of the Physician in the United States of America 
 and Definition of Damages. 
 
 Most indemnity claims in America are adjusted according to 
 the opinion of a reputable physician, more especially on the advice 
 of the official medical adviser or examiner of the insurance, traffic 
 or manufacturing company, or of the U. S. Pension office physi- 
 cian, or upon the s-vvorn statements of those deputized for exami- 
 nation of the special case, with the exception of contested cases 
 and suits for damages, etc., which are settled in the courts of law. 
 In most of the States of the Union, the physician or oculist may 
 be compelled to testify as a common witness or may be brought into 
 the case as an expert; in either event he may be required to give 
 expert testimony. 
 
 The principles of expert evidence and medico-legal expert testi- 
 mony are outlined by Sinkler (Baudry 4) as follows : 
 
 (a) As TO Expert Evidence in General. — A principle of the 
 law of evidence is stated by an authority on the subject as follows : 
 ''The fact that any person is of opinion that a fact in issue does 
 or does not exist is deemed to be irrelevant" (Stephen 42). But 
 the same writer notes an exception to this rule. "Matters of 
 opinion are admissible." "Where there is a question as to any 
 point of science or art, the opinions upon that point, of persons 
 specially skilled in any such matter, are admissible." The words 
 science or art are taken to include all subjects on which a course 
 of special study or experience is necessary to the formation of an 
 opinion. "But opinions of experts are admissible only in relation 
 to their art, and not as to matters of common knowledge." 
 
 Medico-legal Experts. — The opinions of medical men are con- 
 stantly admitted as to the cause of disease or death or the conse- 
 quences of wounds, or the treatment of sickness ; and as to the sane 
 or insane state of a person's mind as collected from a number of 
 circumstances, and as to other subjects of professional skill (Tay- 
 lor 43.) But his special knowledge must be established and his 
 examination confined thereto (Greenleaf 9.) "A physician may 
 testify as to cause of death (or disease), from personal examination 
 or knowledge, but his testimony extends no further than the im- 
 mediate cause, because, manifestlv. that is the limit of science." 
 (Wis. Eepts., Vol. 101, p. 278.) (50)
 
 14 DAMAGES. 
 
 As TO What Should Form the Basis of the Expert's Testi- 
 mony in a particular case; the opinion, to be admissible, must be 
 founded either on his own personal knowledge of the facts testified 
 to in court or upon an hypothetical question (Bell 6.) His evi- 
 dence as to facts must be the result of his own examination. A 
 physician may not give his opinion as to a case in, which he was 
 called into consultation and where his knowledge of the case is 
 derived solely from the discussions with his fellow-consultant. A 
 physician's opinion is not admissible if based on statements made to 
 him by parties out of court and not under oath (Lewis 23.) 
 
 (b) Legal Measure op Damages. — Damages is defined by 
 Taylor (44) as "the injury or loss for which compensation is 
 sought," and the measure of damages refers to the amount or ex- 
 tent of such injury or loss. Three distinct kinds are recognized 
 and awarded to suit the merits of the case : 
 
 First. ISToMiisrAL Damages, or some trifling sum which is 
 awarded when a breach of duty or infraction of the plaintiff's right 
 is shown, but no serious loss is proven to have been sustained. 
 Such are awarded for violation of a plaintiff's right, but where no 
 damages are shown by the evidence. 
 
 Second. Substantial or Compensatory Damages. — These 
 are such as are designed and awarded to compensate for the actual 
 loss or injury sustained. The jury weighs the evidence and fixes 
 the amount which in their opinion properly compensates the in- 
 jured party for the loss suffered. 
 
 In this work only the after-effects of the accident, the economic 
 damage, is figured. In addition to this, American courts allow the 
 amount actually expended in the necessary treatment following the 
 accident, the monetary valuation of the time lost, the amount of 
 injury to the business of the individual, and indemnity is claimed 
 and allowed for tlie mental effect, the pain and anguish suffered 
 by reason of the accident. The amounts of all these factors are 
 arbitrarily allowed together by the courts. The only factor that 
 can he fixed with scientifi.c exactness is the actual loss to the earning 
 ability which follows the accident, the estimation of tvhich is the 
 business of this hooh and which should be the principal basis fori 
 settlement of all claims. 
 
 Third. Exemplary or Punitive Damages, also termed vin- 
 dictive. This class exceeds the loss actually sustained, and is given 
 as a kind of punishment to the defendant. 
 
 §3. Accident Insurance in America and Estimation of Indemnity 
 for Accidents to the Eyes. 
 
 (a) The Estimates Made by the American Accident In- 
 surance Companies are now based upon empiric ideas and the 
 results of experience, such as the proportion of eye injuries to those
 
 RULIXGS OF ACCIDENT IXSURAXCE COMPAXIES. 15 
 
 of the other parts of the body, upon the ratio of losses to the whole 
 number of insured, and upon the amount of premium the insured 
 is willing to pay in ordinary risks. In other words, the general 
 principle of insurance is the foundation for the incurring and set- 
 tlement of eye cases (Hansell 17.) For example: "When the 
 loss or partial loss of vision totally disables the insured from per- 
 forming all his duties, total disability is paid. When it disables 
 him from performing one or more of his duties, partial disability 
 is paid. This ruling naturally holds in cases of disability from 
 other than ocular causes" (Preferred Mutual.) The Travelers' 
 Insurance Co. said: "There is no general method of estimating 
 the pecuniary disability in cases of partial loss of vision for several 
 reasons. One will sutfice. Xo accident policy ever written has 
 undertaken to estimate such disability. On the contrary, the in- 
 surance contract is either a valued policy, fixing a definite sum in 
 the event of loss of vision in one or both eyes, or it names a definite 
 sum to be paid as weekly indemnity for total or partial loss of time 
 resulting from eye injuries." The Aetna Co. replied : "The 
 method of estimating pecuniary indemnity in cases of partial or 
 complete loss of vision from accident, depends upon the form of 
 2X)licy which the insured has purchased. If his occupation is such 
 as to entitle him to insurance in the select or preferred class, the 
 indemnity payable for total loss of sight of both eyes woiild be 
 ec|ual to the full amount of his insurance, being therefore placed 
 upon the same basis as a fatal accident. The loss of the entire 
 sight of one eye is compensated for by the payment of one-eighth 
 the amount that would be paid for the loss of both eyes. If the 
 loss of sight is partial (temporary') and its temporary loss results 
 in the insured being unable to perform the duties of his occupation, 
 he is indemnified for such loss of time simply, just as though he 
 were injured in any other organ. As to loss of vision from dis- 
 ease: under our special health policy provision is made that in 
 such an event an amount equal to 100 weeks' indemnity for 
 total disability will be payable. Payments made bv insurance com- 
 panies for such loss Avere originallv arbitrarily fixed and the ex- 
 perience of the companies has not been of such nature as to make 
 it necessary to modify the same materially." 
 
 Thus bv agreement between the insurance companies and the 
 insured, the former assume the risk of being called upon to pay 
 sums ranging from $600 to $1,000 for one, and $5,000 for the loss 
 of both eyes, provided the insured pays a certain yearly sum. The 
 amount is determined by the ratio of eye injuries to injuries of 
 other parts of the body and to fatal injuries, taken from a large 
 number, and the willingness of the insured to pay a yearly 
 premium commensurate with his own conception of the pecuniary 
 value of an eye and of vision and of the risk he believes he incurs. 
 This is a purely mutual and financial arrangement and is made in- 
 dependently of age, sex, occupation (excluding special risks) and 
 annual income.
 
 16 U. S. BUREAU OF PENSIONS — GERMAN LAW. 
 
 (b) The United States Bureau of Pensions has fixed the 
 rates of pension for disability arising from disease of the eyes thus : 
 "Total blindness of both eyes $72.00 per month; loss of one eye 
 $17.00 per month; loss of sight of one eye $12.00 per month. In 
 cases of disease of eyes causing defective vision, the rates vary 
 from $6.00 to $50.00 according to rank and pay." (17) 
 
 §3. The Oerman Accident Insurance Law. 
 
 July 6, 1884, there was an accident insurance law passed (von 
 Woedtke 46) which is now in force in the German Empire. § 5 
 defines its intention as follows: Compensation for the loss re- 
 sulting from bodily injury or death is to be adjusted according 
 to the following provisions : 
 
 1. The cost of necessary treatment commencing at the begin- 
 ning of the 14th* week after the accident. 
 
 2. A regular income to be paid to the injured person from the 
 beginning of the 14th week during the time of his inability 
 to work. 
 
 The wording of the law shows that neither the injury itself 
 nor any temporary results, such as the detention from work or the 
 expense of treatment up to the 14th week thereafter, is considered 
 grounds for indemnification, but it relates solely to the effects when 
 they have had a more permanent detrimental influence upon the 
 earning powers. 
 
 Section II, § 5 shows that the law-makers had nO' other inten- 
 tion and the law should not be interpreted in any other sense. The 
 law does not mean that under all circumstances injured persons 
 should receive indemnification. 
 
 We agree with Mooren (29, p. 29) when he says, "The presence 
 of an ocular imperfection does not constitute a claim for indemni- 
 fication, but only the existence of inability to follow a trade or 
 profession resulting from such imperfection can be so considered." 
 If the physician desires to do his duty, he cannot depart from this 
 interpretation of the law. While there is no doul)t that the effect 
 of this Accident Insurance Law is not to indemnify the insured for 
 the injury itself, but only for the impairing of the earning ability, 
 it has not yet been definitely decided who shall be the authority 
 for determining the extent of this loss of earning ability and es- 
 pecially the amoamt of the indemnification. Some claim that this 
 is the duty of the physician, others that it is the exclusive right 
 of the courts and the insurance officials. 
 
 •It will be noted that this Insurance Law deals only with the results of accidental 
 injuries after 14 weeks have elapsed from the date of the accident. The reason for this may 
 lie in the fact that most German manufacturers pay their City Hospitals certain sums, 
 (which have been retained from the workman's wages) for the care of their sick employees 
 and indemnification for accidents is considered due only after the lapse of 14 weeks. 
 
 What is an eye worth in America ? To any of us sisht is priceless, but the courts 
 award from $1,0(10.00 to $8,000.00, the latter being the highest indemnity yet given. See Dela 
 Vergne Refrigerator Co. vs. Stahl, Court Civil Appeals, Texas, 1901, Journal A. M. A., 1901.
 
 DETERMINATION" OF DAMAGE BY PHYSICIANS. 17 
 
 §4. The Determination of the Corporal and Economic Damage 
 from Injuries Belongs to the Physician, the Estimation of 
 the Monetary Compensation to the Corporations and the 
 Courts. 
 
 Foerster (7, p. 16) considers that the duty of the physician is 
 only to attest to the kind of injury, leaving the estimation of its 
 effect upon the earning ability to the trade assoiciation. To this 
 we cannot agree; for instance; what help will it be to the in- 
 surance officials or to the average juryman if we inform them 
 that a certain injured person has suffered from "a paralysis of the 
 musculus externus sinistra?" In order to properly judge of the 
 relations between the laming of an ocular muscle and the earning 
 capacity, technical physiologic knowledge is certainly needed, and 
 verily, we cannot expect a tradesman to have a scientific mind. 
 A physician can much sooner acquire a knowledge of the technical 
 peculiarities of the different trades than the trade association can 
 get even a modicum of medical knowledge. There are but few 
 vocations with which a physician does not come in contact. Wag- 
 ner (38, p. 21) states that it is the duty of the physician to acquire 
 some knowledge of the trades of the patients with whom he deals, 
 as by this means he is enabled to estimate the relation of the injury 
 to the loss of the earning ability. To the foregoing we heartily 
 agree. It is the province of the physician to estimate the propor- 
 tional loss to the earning ability resulting from disease or trauma- 
 tism, for who among men is, from his training and daily work, so 
 well qualified, and whose business brings him into closer relations 
 with such economic problems? The question of monetary com- 
 pensation, the sordid matters of dollars and cents, may be left to 
 the business corporations and the courts of law.
 
 18 zehender's formula. 
 
 CHAPTER IL 
 
 DIFFERENT METHODS FOR ESTIMATION OF LOSS OF THE 
 EARNING ABILITY FROM OCULAR INJURIES. 
 
 §0. Zehender's Formula. 
 
 Zehender was the first who' tried to make a rule for the esti- 
 mation of the loss of the earning powers from ocular injuries (53.) 
 His publication provoked a series of papers by other German writ- 
 ers who declared that liis premises were incorrect and his calcu- 
 lations illogical. We, therefore, give a critical resume of the 
 several methods of mathematical computation that have been pro- 
 posed, showing their errors, and then proceed to the exposition of 
 the method of Magnus, which for accurate scientific work seems 
 to us to be the most satisfactory. Zehender gave a formula founded 
 upon a suppositious case where the sight of one eye is entirely 
 lost while that of the other remains normal. He supposed that 
 such a normal eye acquires a much higher value (even double) 
 than formerly. 
 
 To compute the amount of vision left after the loss of one eye 
 
 by his method, three eye values must be considered, two for the 
 
 normal eye and one for the blind one, which he places in the form 
 
 2 >< 1 + 2 
 of an arithmetical equation thus, = -^, The visual 
 
 faculty in such a ease is, therefore, two-thirds of normal. 
 
 If Zehender's supposition be right and if after the loss of one 
 eye, we really had to figure with three quantities, there would be 
 nothing to say against its correctness, but it is arithmetically in- 
 correct in its conception, for, if we double the value of any object, 
 we do not make by this manipulation two different ones but one 
 which is only of a different value and therefore by such an equa- 
 tion applied to eye values we only change the quality of the two 
 eye values, the number remaining the same. Although this fact 
 may be self-evident, we will exemplify it as follows : Supposing 
 a man owns a house which thro'ugh some fortunate event would be- 
 come twice as valuable as formerly, would anybody believe in this 
 ease that the man now owns two houses? Let us vary this ex- 
 ample and suppose that this man owns two houses of equal value, 
 one of these increases in value to double, the other through some 
 accident depreciates entirely, would anybody conceive the idea that 
 this particular man now owns three houses or claim that he would 
 have to figure with three houses in the valuation of his property? 
 Zehender however has come toi such a curious conclusion, so that, 
 by his formula, we would have to figure, in the case of the one- 
 eyed man, with three eye values. He has made a one-eyed person
 
 GROENOUW'S FORMULA. 19 
 
 into a three-eyed one. Zehender's error is in supposing that he 
 really creates by the enhanced valuation of one thing, a new and 
 second self-existing object. Thus, if we woaild express the earn- 
 ing ability by his speculative proposition and arithmetical example, 
 but avoiding his serious mathematical and logical errors, the for- 
 
 2-1-0 
 mula would be : rni^i * ^^^' ^^ ^^^^ formula would give for the 
 
 earning ability, notwithstanding the loss of one eye, the full value 
 O'f one, the consequence is that Zehender's expression cannot be 
 used in the proper mathematical way. Thus Zehender's formula 
 belongs only to history. jSTevertheless, he should be accorded the 
 honor of having first shown that the mathematical method is the 
 correct way for estimation of the ocular earning ability. 
 
 §6. GroenoHw's Formula. 
 
 (a) Groenouw (12, p. 34) uses a formula which likewise does 
 not give the normal physiologic and economic value for vision, but 
 like that of Zehender's, it rests upon a pathologic process of injury 
 to the faculty of sight. He begins with the supposition that the 
 stronger eye possesses a greater economic value than the weaker 
 one. If the difference of the visual powers of the eyes be some- 
 what great, then the better eye would alone be accustomed to work 
 while the weaker would count very little in regard to earning abil- 
 ity. Groenouw expresses this supposition l)y taking first an arith- 
 
 O-pi I op 
 
 metical proportion of the visual power of both eyes, , -. in 
 
 which Se stands for the better and se for the poorer eye, and by 
 this formula the better eye (Se) is given m times greater value 
 than the poorer one. We would therefore transpose the foregoing 
 
 formula into ^L><S^_±^. He also adds to this expression the 
 
 M -f 1 
 value of the visual field P making the expression for the earning 
 
 ,.,., ^ mXSe + se^ 
 abilitv, E = r^ P. 
 
 ' M + 1 
 
 As Groenouw's formula does not represent the value of normal 
 physiologic vision for earning purposes but rather the value of an 
 already pathologically changed faculty, therefore, it cannot be 
 used for a general expression of economic vision but only for some 
 certain special case. In Groenouw's equation E stands for the 
 earning ability which is the unknown quantity and the results to 
 be sought by all the equations considered in this book, m stands 
 for the greater value acquired bv the sound eye after injurv to its 
 fellow. This enhancement is likewise unknown. Se is the cen- 
 tral visual acuity of the better eye which can be ascertained by 
 functional examination, se is the visual acuity of the poor eve 
 which is likewise to be found. P is the value of the visual field 
 which can be ascertained. We have now in Groenouw's formula an
 
 20 GROENOUW'S rOEMULA INAPPLICABLE. 
 
 equation with two unknown quantities, E and ]\r, and three known 
 quantities, Se^ se and P. But such an equation has numberless 
 solutions, as it is possible to compute from the values given to one 
 unknown quantity separate values for the other (the exceptions are 
 only the so-called diophantic equations which cannot be considered 
 in this connection.) As this formula admits of numberless solu- 
 tions we ma}' therefore consider it inapplicable for our purpose, 
 for we would be unable to tell which of the numberless possibilities 
 would be the right one in a given case. An equation which is able 
 to give a single precise answer is the only practical one. Thus, 
 from the very start, with his equation containing two unknown 
 quantities, Groenouw got into a desperate position because he pro- 
 posed a formula which cannot be treated in a correct mathe- 
 matical manner. 
 
 (b) The estimation of ocular damage by Groenouw's formula 
 
 . ,, • • 1 p -n M X Se + SE „ . , ., , 
 
 m the original form, E = r^, P is not possible, 
 
 ° M + 1 ^ 
 
 because the two unknown quantities contained therein cannot be 
 figured out of this one formula. Groenouw, however, extricates 
 himself out of tliis disagreeable situation by forcibly pressing his 
 formula into a more desirable form, which allows of a certain kind 
 of estimation of the damage to central and peripheric vision. Be- 
 fore we can take up the subject of these cases in which there is 
 partial damage to the visual faculty but no actual blindness, we 
 must first regard the working of this formula in the case of a 
 one-eyed man. 
 
 (c) We are of the opinion that Groenouw's formula cannot be 
 properly used in the ease of monocular vision : For he conceives 
 that there is a certain proportional value between the ]x>wer of 
 sight ill the better and that of the poorer eye, the better eye having 
 M times earning value over that of the poorer (12, pp. 35, 36, 37), 
 i. e., that the better eye (13) exercises an m times greater influ- 
 ence upon the earning ability than the poorer, but if one eye is en- 
 tirely blind, this proportional valuation is simply impossible be- 
 cause a blind eye is never of any assistance to the earning ability 
 and does not, therefore, possess an earning value; then the poorer 
 €ye cannot have an m times greater value than the blind one, for 
 the earning value of the blind eye is equal to nothing, and m times 
 this is also nothing; therefore, the mathematical rule which 
 shows that the multiplication of a number value with naught makes 
 it alwavs l)ecome naught, render? Groenouw's calculation a mathe- 
 matical absurdity, in that according to his rules a one-eyed person 
 must be entirely incapable of earning anything. 
 
 In Groenouw's formula E, the earning ability, and :m, the en- 
 hancement of the earning value of the better eye, is unknown. 
 Se. the sight of the healthy eye, equals 1 ; se. the sight of a totally 
 blind eye, disappears entirely out of the formula : P, the visual field, 
 is given by him a value of 9-10, which has been found by exact
 
 GROENOUW'S FORMULA. 21 
 
 physiological examination and wliicli we will here accept in a case 
 of monocular vision, Groenouw constructs the following formula: 
 
 M + 1 
 
 This formula is constructed in an arithmetical equation similar 
 to that of Zehender's. As long as both eyes could see, the better 
 63^6 with the power Se would have m times value over and above 
 the poor eye, se^ thus the numerator of the arithmetical equation 
 would be:MXSE+SE. But if one eye grows blind, its faculty of 
 seeing is then entirely omitted, the numerator then becomes m X Se 
 or because Se is 1 it equals ii ; the simplified formula thus being : 
 
 E = ^P. 
 
 M + 1 
 
 If the value se^ one of the two values out of which the arith- 
 metical proportion is formed, is entirely omitted, its influence is 
 •exerted not only in the numerator but in the denominator of our 
 fraction. Thus the numerator of the formula would be reduced 
 to M + 0, as the numerical earning value of the blind eye is o. 
 Whether a blind eye is in the head or has been removed by an opera- 
 tion is entirely foreign to this subject, as, if it is blind, it must be 
 regarded as non-existing as far as it relates to the earning ability 
 and must be treated accordingly in the denominator of the arith- 
 metical proportion, which is, therefore, m + o. Groenouw, however, 
 ■calls the denominator m + 1, whether one eye can be counted or not, 
 and thus in the formula which should represent solely the physio- 
 logic earning value rates a blind and therefore non-existing eye 
 with a positive earning value of 1. 
 
 Groenouw has confounded the physiologic with the anatomic con- 
 ditions; for the physiologic purposes a blind eye is practically the 
 same as if it were non-existing, and because he has done so he pre- 
 sents in the further course of his calculations with human beings 
 who have theoretically nine seeing eyes, for instance, in a concrete 
 ease in which one eye has visual acuity of ^ and the other l/l , the 
 
 8 + - + - 
 earning ability is expressed thus : E = * ^ 1, and this is 
 
 nothing else but the arithmetical proportion of the faculty of 
 vision of a being who has nine seeing eyes. The outrage upon com- 
 mon sense is none the less if the human being be likened to a cyclops 
 or to a nine-eyed monster. One of the two suppositions has to be 
 chosen if Groenouw's formula be used, because it does not admit 
 of the consideration of a normal being having two seeing eyes. 
 "We have shown that the text of Groenouw's formula is erroneous 
 and will now regard the manner in which he uses it to express the 
 earning abilitv of the one-eved person, for which his formula is, 
 
 E = ^P.' 
 
 M + 1
 
 22 FORMULA OF IIEDDAEUS. 
 
 In this formula E and the enhancement of value of the sound 
 eye, :m, are unknown. Here is again an equation with two un- 
 known quantities which has no fixed but numberless solutions. 
 Such mathematical difficulties are passed over by Groenouw in the 
 following manner: He first supposes that the income of a one-eyed 
 person is 33 I/3, therefore the earning ability must be 3-^ , and with- 
 out any reflection he inserts this arbitrary value into his formula 
 
 M 
 
 thus : ^ = — r-- Mo. In this equation m can be figured with- 
 M + 1 ^ *= 
 
 out any difficult}^, which would be about 3. But we can, of course^ 
 
 have as great a number of values for m as that for E, but for 
 
 which Groenouw has made an arbitrary valuation, ys or /^ (7,p.35), 
 
 and which anybody has the privilege of changing. If we would 
 
 figure b}^ his method, we would form such a fluctuating equation 
 
 that E could not be mathematically considered. 
 
 (d) Groenouw further handles these doubtful and fictitious val- 
 ues in the following way : For the estimation of injuries in which 
 the central visual acuity has been injured, but total blindness not 
 resulting: Here he does not hesitate to generalize the values for 
 M which he forced into his equation in the case of one-eyedness 
 and uses them in the calculation of other cases in which both eyes 
 see, despite the fact that the value of the vision in the seeing eye 
 in one-sided blindness is quite different from that of the better eye 
 in another case where some sight remains. The earning ability 
 of a one-eyed person is quite a different thing from the earning 
 abilit}' of a normal being, and these terms are not interchangeable. 
 Thus, Groenouw's formula, being based upon fictitious values and 
 improperly formed, cannot be used for the scientific estimation 
 of the economic value of vision. 
 
 §7. The Formula of Heddaeus. 
 
 Heddaeus (18) bases his calculations upon the indisputable 
 fact, that if the faculty of sight be reduced to one-half, the re- 
 mainder represents a proportional greater amount of earning ability 
 than that which has been lost. This observation causes him to sup- 
 pose that the loss of earning power is equal to the square of the loss 
 of Wsion. We cannot see Avhy only the square and not the cube 
 or the fourth or any other power should not designate the above 
 proportion. This is simply an arbitran- decision of Heddaeus and 
 is not founded on the real proportion. In his writings, he does 
 not give any mathematic, physiologic or economic proofs of the 
 correctness of his proposition. Heddaeus makes one assertion to 
 which we must most emphatically protest, for he brings the factor 
 of binocular vision in connection with ocular injuries into a most 
 unwarrantably prominent ])osition. In the case of acquired mo- 
 nocular vision from accidents, he asserts that the diminution of the 
 earning abilitv is onlv affected bv the loss of binocular vision and
 
 FORiLULA OF HEDDAEUS INAPPLICABLE. 23 
 
 that this factor and the loss of the power to estimate distances 
 correctly, is the most essential factor for the loss of the earning 
 power. This supposition is ridiculous ! Although, immediately 
 after the loss of one eye, the faculty for estimation of distance 
 and size of objects is lost for a while, and is detrimental to the 
 earning ability, and therefore should not be underestimated, it dis- 
 appears entirely in a comparatively short time. 
 
 By examinations (Magnus 26, p. 38) of the one-eyed laborers 
 among the iron and steel workers in Silesia, it was found that fully 
 70 per cent, of those who were blinded in one eye had learned to see 
 ■easily and estimate distances correctly. As this faculty is restored 
 to every one, it needs only passing consideration.
 
 24 GENERAL PRIXCIPLES OF MEASUREMENT. 
 
 CHAPTER III. 
 
 §8. General Principles for Estimation of the Relations of Ocular 
 Injuries to the Earning Ability. 
 
 The fact, that during the last few years so many different 
 propositions for the estimation of the economic value of vision have 
 been proposed, shows that the general principles involved in deter- 
 mining the earning ability are not yet clearly understood. We will,, 
 therefore, search for and explain certain general principles for 
 this estimation which will serve as a basis for that relating to the 
 visual act which is one of the functions of the general organization. 
 We will give the visual earning ability a prominent part in our 
 considerations. 
 
 If in a given case we desire to mathematically determine the 
 amount of power of any bodily function, we first have to find a 
 general expression for the normal ability of the particular organ. 
 We usually determine such expression by taking the average of a 
 large number of measurements of the particular function and 
 designate this average as an expression of the normal powers. In 
 this way we have formed the standard of visual acuity, of the visual 
 field, of the normal light and color sense, etc. Starting from this 
 average value, we measure the power of the organ in any special 
 case. The difference between its power and our standard is a 
 fraction which in the case under examination may represent the 
 amount of damage done to the function. This we do in the estima- 
 tion of the pathologic diminution of central visual acuity and with 
 limitations of the visual field. When we succeed in creating such 
 an average normal value of the function of an organ or bodily 
 power, we can then estimate the amount of individual acts, as if 
 measuring a piece of cloth with a yard-stick. This method is used 
 in the other natural sciences as well as in medicine. Therefore, we 
 must first fix an expression for the normal ocular earning ability 
 before we can estimate the amount of individual cases. The objec- 
 tion that the application of this principle to the act of vision and 
 the resultant measurements Avould be arbitrary, holds good to 
 but a limited extent, for where a conception of the normal func- 
 tion has been developed from a series of definite measurements 
 from which the average value has been estimated, we do not speak 
 arbitrarily, especially where this conception has been upheld by 
 other findings, the products of searching inquiries of a scientific 
 character; but we must remember that a function of a body or a 
 natural power is a need which cannot be weighed with the scales 
 or measured bv the yard, and therefore we cannot entirely do with- 
 out certain arbitrary suppositions.
 
 GENERAL PRINCIPLES OF MEASUREMENT. 25 
 
 In our opinion thei'e is only one way for the establishment of a 
 formula for the normal ocular earning ability, and that is, by the 
 separate estimation of the value of each physiologic factor form- 
 ing the sense of sight, and by the addition of these component parts 
 the normal value of vision may be established. The construction 
 of such a formula is facilitated by the fact that we already have 
 established the physiologic value for the more important factors 
 entering into the visual act, i. e., the central visual acuity and the 
 field of vision. But the normal physiologic act of vision is a com- 
 posite quantity formed of different factors which have more or less 
 relation to the economic value of the eye. We may exclude those ■ 
 factors which are without economic importance for the salce of our 
 subject. We thus form out of the composite act of seeing a reduced 
 or economic estimation of the visual act. In order to do this we 
 must fuse, bring into or eliminate certain of these factors to satisfy 
 our purpose. As we have placed the visual earning act in a normal 
 position (chap. IV., § 9), we will use the same method for deter- 
 mination of its factors. Damaged ocular earning ability will al- 
 ways be considered as a fraction of the normal power. This 
 method, which permits of a mathematical estimation of each por- 
 tion of the visual act as a fraction of the normal, must be consid- 
 ered to be complete, as it is in perfect harmony with the principles- 
 laid down by the natural sciences in measuring the work of any 
 organ or power. 
 
 Judging by this standard, we must consider that the proposi- 
 tions of Zehender, Groenouw and Heddaeus were on the wrong track 
 from the very start. None of these authors developed an expres- 
 sion for the normal physiologic act of vision. Their formulae for 
 expressing the economic value of vision stand absolutely on patho- 
 logic grounds and they introduce self-constructed pathologic sup- 
 positions into the calculations, instead of looking at the earning 
 ability as a quantity resulting from a combination of the different 
 parts composing the physiologic act of vision. Thus these for- 
 mulae are not expressions for existing conditions, but are nothing 
 but the mathematical sediment of intuitions arbitrarily conceived 
 by these authors. As they have departed from the physiologic and 
 only reliable ground for arbitrary hypotheses, their theories are 
 shown to conflict, in a most humorous manner, with the physiologic 
 ocular conditions in a healthy person. Thus, according to Zehen- 
 der's calculation, a human being would have three seeing eyes, and 
 Groenouw acts as if nature had given him nine eyes or put him into 
 the world as a eyclops.
 
 26 THE EARXIXG ABILITY. 
 
 CHAPTER IV. 
 
 THE CONCEPTION OF THE EARNING ABILITY AND INJURIES 
 
 THERETO. 
 
 §9. The Meaning of Full Earning Ahility. 
 
 If we would conceive of an injury to the earning ability as a 
 quantity which can be given a mathematical value, we would have 
 to start from an estimation of the complete earning ability, which 
 in a healthy normal individual is a comj^osite quantity resulting 
 from three factors : — 
 
 (1) The unimjjaired functional power of the bodily organs. 
 
 (2). The technical knowledge which is necessary for the carry- 
 ing on of the vocation. 
 
 (3). The ability of the individual to compete in the labor 
 market. 
 
 In an opinion given by the Imperial Insurance office Xov. 26, 
 1887 (Becker 5, p. 10), the meaning of the earning ability is thus 
 stated : 
 
 ''In judging the earning ability the bodily and intellectual con- 
 dition of the injured person has to be considered in connection 
 •with the preparatory education and. also his capacity for earning 
 a living." In this definition, "bodily and intellectual condition," 
 is the same as the first of our elements (1), the unimpaired func- 
 tional ability of the bodily organs ; the so-called "preparatory edu- 
 cation," would correspond with our (2), the technical knowledge 
 necessar}' to the calling; and our (3), the capacity or ability to 
 compete in the labor market, is defined in the official definition as 
 ^'capacity for earning a living." 
 
 These elements cannot be regarded as equal in value. Doubt- 
 less the functional condition of the bodily organs is of the first im- 
 portance for successful work. The preparatory education or knowl- 
 edge is of nearly equal value. Much less importance should be 
 given to the third element, the ability to compete in the labor 
 market. This is dependent upon the value of the two others, be- 
 cause the ability of an artisan to battle against competition de- 
 pends largely upon the condition of his health and his technical 
 knowledge — our two first elements. We have divided the concep- 
 tion of the earning ability into its three fundamental elements 
 solely because such an analysis makes it possible to put the normal 
 earning ability into a mathematical formula. Thus we designate 
 the eamincr ability itself E ; the first of our elements, the func- 
 tional abilitv. F ; the second, the necessary knowledge, Y ; and the 
 third, the ability to compete. K. In this formula we put the two 
 quantities, F and Y, in their full value and accept K as a root
 
 FACTORS OF EARNING ABILITY. 27 
 
 value. There would be nothing c-haaiged in the total value of the 
 formula itself because as the root of 1 is always 1, and we regard 
 F, V and K as 1, it is immaterial for the formula itself if we 
 take one of the three quantities as a root or not, but this proportion 
 immediately changes when the part introduced as a root grows 
 smaller than 1, as happens in each ocular injury, because the root 
 of each genuine fraction is always greater than the fraction itself. 
 Thus the influence of K, after being introduced as a root value, if 
 
 K K 
 
 it has fallen off by an injury to - cannot be any more 
 
 but must be greater, for instance, " . Therefore, the damage to 
 
 the total value of the formula will be smaller if we take K as a 
 root value. By the total elimination of K the earning ability 
 will not be diminished, but it will be by a smaller damage, according 
 to the influence the damage of K shall exercise upon the value of the 
 total formula. We will have to choose the exponent of the root 
 as smaller or greater, according to its rating. The value of a root 
 of a genuine fraction is much great^* if its exponent is small. 
 Therefore, if we wish to lower it considerably, we take a small, if 
 we wish to effect it less, a greater exponent for Iv. While the 
 ability to compete, K, is comparatively very little impaired through 
 minor ocular injuries, it is very much so through the loss of one 
 eye; we suit these conditions by choosing a greater exponent of 
 the root in slight injuries, but a smaller exponent for serious ones. 
 We will adopt for the slight injuries K as the 10th root and 
 for serious ones according to the demands of the profession, 
 the 7th root or the oth root. We will more fully explain this in 
 one of the following chapters. An exact calculation of such a 
 changeable quantity so dependent upon the individual cannot be 
 made. The calculation of the competing ability cannot be waived 
 entirely, as does Groenouw, who submits in each case the estimation 
 of this important factor to the pleasure of the examiner. We have 
 started out to make a practical mathematical formula, but should 
 include all factors that are relative; as we will show further on, the 
 peculiarities of the individual case may ahvays be considered. 
 
 When we express the earning ability through the three factors, 
 F, Y and Iv, we present E, not as a sum. but as the product of these 
 
 X 
 
 quantities, as multiplied thusly : E=FVV' K, in which the exponent 
 X changes with the degree of the functional damage. E must al- 
 ways be regarded as a product and not as a sum, to meet all possi- 
 bilities occurring in practice. If Ave add F. Y and Iv, the formula 
 would give wrong practical results, as we see in the following ex- 
 ample: Supposing both eyes were lost in an accident, the quantity 
 F of our formula would be 0. If we had connected F, Y and K 
 
 with the +, flncl added, even if K would have become 0, Y -\-V K^ 
 which is the remainder of the eamins- abilitv. would have been left.
 
 28 -WORKING ABILITY AND EARNING ABILITY. 
 
 This would be entirely wrong, because a lalwrer who has lost his 
 functional ability, especially the sense of sight, should be regarded 
 in an optical way as entirely unable to earn. Taking the same ex- 
 ample and using our formula with F=0, E immediately becomes 
 0, because each product is always if one of the factors is 0. If 
 we would leave Y out of our formula, E of course =0, and actual 
 practice confirms this, because even the most simple hand work 
 requires a certain amount of preparatory education. Finally, if 
 we drop the third factor, the 10th root of K, the normal earning 
 ability according to our formula becomes 0, which is likewise 
 shown by practical experience, because, even though an indi\ddual 
 is in good health and by reason of preparatory education has the 
 skill to work, if his work is not needed, his economic value is nil. 
 He may possess the power of working, as the factors F and V are 
 present, but he only has earning ability when he can dispose of the 
 work in the economic market. Therefore, if from our formula 
 
 (E=F V K K ) we take away the factor V K (the ability of the 
 individual to dispose of his work), the remainder, which is the for- 
 mula for the working ability (A), would be A==F V. 
 
 The "working ability*" is not synonymous with "earning ability," 
 although some -authors would have it so, for instance, Becker 
 (5, p. 9) : "The words "working ability' and 'earning ability' 
 may be regarded identical in meaning, because in each worker the 
 latter depends upon the former.'' Even if this be so, the two con- 
 ceptions are not the same, and such a rendition obscures the concep- 
 tion of the earning ability, our definition of which should be 
 clearly understood. 
 
 The calculation of injury to the earning ability proposed by 
 us starts from the formula for the full earning ability : 
 
 E = F V K K.
 
 DAMAGE TO EARNING ABILITY. 29 
 
 CHAPTER V. 
 
 §10. Determination of the Amount of Injury to the Earning 
 Ability According to Magnus. 
 
 When one or more of the factors forming the earning ability 
 is injured, an idea of the amount of damage to it may be formed 
 if we first consider to what extent tlie single factors are injured. 
 We will find that the application of mathematics to tliis subject 
 will prove somewhat complicated, as we will have to first separately 
 ■estimate the damage to the different factors and then fix the value 
 of the total formula. Under certain conditions, this task may 
 become decidedly complicated, as some of these factors forming the 
 complete earning ability are composed of several elements which 
 have to be figured separately. This is especially the case with the 
 act of seeing (F of our formula), which, as we will see directly, 
 •consists of three separate parts, each of which may be damaged in 
 a different way. To ascertain the value of the factor F, we have to 
 solve three mathematical problems, but in return, our method of 
 •estimation does not alone offer the possibility of giving a mathe- 
 matical expression to the different forms of damage to the ocular 
 apparatus, but also allows us to do this in an accurate manner, 
 with due consideration of the different individual conditions in 
 ■question, and finally our method solves the mathematical prob- 
 lems (chap. Ill, §8) in a satisfactory manner. It starts from 
 the physiologic ocular earning ability and designates the damage 
 thereto as fractions of the normal value, making our method right 
 in its principle and easy to comprehend. The calculation of our 
 formula is simplified by the fact that our factor V (the prepara- 
 tory education), may be entirely cut out in estimating injury to 
 the earning ability. As important as this factor may be to the 
 normal earning ability, we may put it aside in a case of accidental 
 damage. The technical education in itself will not be injured di- 
 rectly. It is only indirectly affected by accidental injury. Cer- 
 tainly the visual function may be diminished to such an extent that 
 the realization of the technical knowledge becomes limited, but this 
 injury to the earning ability in such a case does not rest upon a 
 diminution of the knowledge and the capacity, biit limitation of 
 their use. We calculate the extent of such limitation, according to 
 our method, directly bv the factor F, i. p., from the performance 
 of the visual act, which is the essential factor in the full eaminij 
 ability, damage to which is synonymous with damage to the total. 
 Calculating F we have already used Y. For simplicity's sake 
 it would be better to omit T entirely. The n'orl-tng formula for 
 
 X 
 
 the earning ability then would be : E=F V K.
 
 30 VISUAL FACTORS. 
 
 CHAPTER VI. 
 
 §11. Estimation of the Damage to Economic Vision. 
 
 Normal physiologic vision consists of a series of difEerent fac- 
 tors : the central acuity, the visual field, light and color senses, the 
 adaptive faculty, the muscular movements and the cerebral proc- 
 esses^ all acting together in creating the sense of sight. We may, 
 therefore, regard the act of seeing as a sum whose numerals are 
 formed by the different functions; if one numeral be taken from 
 the sum which represents the complete act of seeing, then the 
 balance will be left, i. e., vision will be damaged to the extent of the 
 loss of one of these visual functions; but vision is yet in existence 
 in a limited way. In the manufacture of a formula for physiologic 
 vision we would have to consider that in losing simultaneously the 
 two most important factors, central and peripheric vision, the act 
 of seeing would be nil ; but from an economic standpoint we could 
 not get along with this idea. The different secondary functions 
 forming sight have different valuations. In calculating the injury 
 to the visual earning ability we will have to exclude cerebral vision 
 because accidental injuries affecting the cerebral centers will hardly 
 ever be of such limited extent that the valuation thereof would be 
 done by an oculist. In such a case the neurologist would be de- 
 manded. The sense for light and color and that of adaption are 
 not themselves to be considered in estimating accidental damage 
 to the ocular earning ability. An injury limited exclusively ta 
 these functions is not known. Theoretically such injuries might 
 be possible, but practically they are not recognized. Such trau- 
 matisms would generally be connected with disturbance of other 
 portions of the visual act, especially that of visual acuity and the 
 visual field. Therefore, we include the functions of the light and 
 color sense and of the adaptive power, when we treat of the dis- 
 turbances of the visual acuity and visual field, as thereby the estima- 
 tion is rendered less complicated. The visual acuity, the field of 
 vision and the muscular movements are of so much more impor- 
 tance that we think we can properly estimate the results of ocular 
 traumatisms by taking into consideration only these latter three. 
 These are to be regarded as the factors of a product and multiplied. 
 Practical experience shows us that we must do this under all cir- 
 cumstances, because for the following of a vocation, none of these 
 factors could be damaged or left out, for without them the earning 
 ability would disappear. If a person loses the central acuity of 
 both eyes, then we certainly have complete earning disability; not 
 even the common laborer having lost his central acuity could do 
 his former work. Such an individual could only take very low 
 grade positions, such as that of a messenger. The possibility of
 
 VISUAL FACTORS. 31 
 
 doing much work in the several trades after the loss of central 
 acuity is so completely excluded from consideration, that it would be 
 extremely incorrect if we did not consider an artisan who had a 
 large central scotoma, i. e., lost his central visual acuity, entirely 
 unable to pursue his vocation and earn anything. If peripheric 
 vision is lost in both eyes, working at trades is likewise excluded, as 
 is readily seen in cases of double-sided hemianopsia. A working 
 man with total paralysis of all the outer ocular muscles is likewise 
 totally disabled. In such a case he Avill stare into vacancy and 
 cannot work in a binocular manner. He would lose the ability to 
 estimate distances and the size of objects, and could only have a 
 certain degree of monocular vision, which could be imagined to be 
 useful only in certain special cases, as that of a nearsighted clerk. 
 Such a ease might be looked upon as a curiosity and would be 
 rather an exception, so that it could not be used to refute our view 
 that the ocular muscles are absolutely necessary for the earning 
 ability. Even the closing of one eye, which Groenouw holds in readi- 
 ness as a remedy for the restoration of the earning ability, will 
 help nothing, for the other will stare immovably if its muscles are 
 paralyzed. The adjustment that is noted in congenital defects 
 cannot be likened to that of acquired ones and cannot be considered 
 in their influence upon the earning ability. The physiologic process 
 out of which an adjustment and an increase up to the earning 
 ability, which has been asserted by Groenouw (13) to have occurred 
 in a case of acquired paralysis of all the ocular muscles, is certainly 
 very strange to us. Therefore, in the case of an artisan with an 
 acquired paralysis of all the outer ocular muscles there is total 
 disability to work. 
 
 In building up a formula for the act of seeing in relation to 
 earning, we denominate the central acuity with the letter C and 
 the visual field with P. The valuation of the muscular motions, 
 M, offers certain difficulties, because the influence of a distur- 
 bance of the function in a single ocular muscle, from a professional 
 standpoint, is quite a different one, AA'hether we take into considera- 
 tion monocular or binocular vision. The monocular act is but 
 slightly affected by paralysis of one ocular muscle, as it only dimin- 
 ishes the motility of the eyeball, but in binocular vision the factor 
 of diplopia comes in and this is of the greatest importance, as it 
 excludes, temporarily at least, retention of working binocular vision. 
 In formation of our formula wo would, therefore, treat the factor 
 of muscular movements in a different manner, when treating of 
 binocular vision, than we would for the monocular act. In the 
 formula for binocular vision we take the muscular movements of 
 each eye as the product of different factors, each of which corres- 
 ponds to the activity of a particular muscle. Now, if we mark the 
 muscles of one eye with ( mi m-z m.{ m^ ms mc ) and those of 
 the other ( mi' m^ ms' m,' ms' me' ) etc., we would represent
 
 32 THE VISUAL FIELD AXD OCULAR MUSCLES. 
 
 the whole muscular activity as (mi m2 irirj m* ms me) (m/ m./ m/ 
 m/ m^'' me')- ^^ this conception the whole product would 
 be 0, by losing one single muscular motion, and therefore 
 the binocular act would be negative. In monocular vision the mus- 
 cular activity should be conceived as the sum of the single per- 
 formances, because by losing one of them only an ocular detriment 
 has been created and not total earning disabilit}', thus mi + mj + 
 ms + mi + ms + me- 
 
 A few remarks about the relations of the different fac- 
 tors entering into the visual act are here advisable. The 
 central visual acuity is, under all circumstances, the most important 
 element for the function of vision. Any injury which reduces the 
 central visual acuity below the lowest limits required in the pro- 
 fession, produces a total disability for that work. Peripheric 
 vision is of less importance and has not as much influence upon the 
 visual act, and injuries to it have a smaller influence to the entire 
 act of vision than the degree of injury of the visual field itself. If, for 
 instance^ the remaining peripheric vision, P, should be denominated 
 
 Y 
 
 with a greater fraction than — , Ave may do this by introducing P 
 as a root value like we did with the factor K for the earning ability 
 
 Y Y 
 
 (Chap. IV, § 9). The root of — would then be greater than -^ 
 
 2y ^ ^ 
 
 for instance . The damage to the total value of the formula 
 X *= 
 
 would be smaller, if P be taken as a root value and the value of the 
 act of vision would not be diminished to the value of P, but to a 
 smaller extent. 
 
 The same is the case with the action of the muscles, but even to- 
 a greater extent, as they are much less important for the monocu- 
 lar act of vision than is the visual field. We will, therefore, add 
 the action of the muscles M as a root value in the formula, but we 
 will take the exponent of this root to be much greater than the 
 exponent of the root value of the visual field. According to 
 mathematical principles the value of the root of a proper fraction 
 increases with the amount of its exponent, thus, if we introduce 
 M with a greater exponent of the root than P, in the case of damage 
 to M, it will exercise less influence upon the total value of the 
 formula. We believe that we may place the relative value of the 
 visual field and the muscular movements by choosing as exponent 
 of the root in the former 2, and in the latter 4. Of course, these 
 are arbitrarily chosen, as it is an undisputed fact that the central 
 visual acuity, peripheric vision and the muscular movements have 
 different nieanings in the act of. vision, the proportional valuation 
 of which cannot be put into figures from observation nor from meas- 
 urement, it is certainly allowable for the mathematician or the phy- 
 sician to estimate the amounts of these exponents differently, but 
 the formula itself will not be changed. We thus reserve for the
 
 FORMULA FOR BINOCULAR AND MONOCULAR VISION. 33 
 
 examiner in each case, the right to make allowance for his individ- 
 ual conception, which factor we regard as a great advantage in our 
 method. Thus our formula for the hinocular act of vision would 
 
 be : S2 ^ C V' P V (mi mz ms m* m5 me ) ( m/ m/ m/ m/ m/ me' ) 
 
 In this formula C is considered the central visual acuit}^ in the 
 better eye, which under normal conditions will always equal 1. 
 
 In case of double-sided damage to the visual acuity, if we desire 
 to condense this formula into that for the monocular act, we should 
 consider that the peripheric vision as well as the activity of the 
 extra ocular muscles M, enter into the monocular act in a some- 
 what different form. The monocular field of vision is a fraction 
 smaller than the binocular. It is commonly only ^ (Groeuouw ^o) 
 of the latter. (An exhaustive explanation of these conditions will 
 be found in the chapter treating of monocular vision.) The extra- 
 ocular muscles have smaller value in monocular vision than in 
 binocular, because in the former those functions of the outer mus- 
 culature of both eyes that are essential in estimating distance and 
 the relations of objects, etc., are missing. Therefore, we here con- 
 sider the value of the musculature as less and estimate it at ^ of 
 the binocular value. This smaller valuation of M may be ulti- 
 mately neutralized if a monoculism caused by accident has existed 
 a considerable period. We compute the formula for the monocular 
 act of vision from the binocular one as follows : 
 
 Si = C Vye P V ^.(mi + m., + ms + m* + ms + me.) 
 
 §12. Estimation of the Economic Limitations of the Central 
 Visual Acuity. 
 
 The central acuity lies within well-known physiologic limits. 
 When it falls below these, the function itself is damaged, but the 
 conditions met with in practice are not such that the physiologic 
 and earning limitations of the central visual acuity are interde- 
 pendent; if it were so, the claim of Zehender (53, p. 266) would 
 stand ; then the smaller the damage of the former, the greater the 
 earning value of the latter, and vice versa. If we desire to have a 
 general rule for the ability of every single ocular function, an aver- 
 age value must be found by many single measurements, but such 
 average values permit of many exceptions and cannot be designated 
 as the average limiting value of the earning ability, for. if such were 
 the case, each variation therefrom might be termed a damage to the 
 earning ability. This may be done by individual measurement of 
 each factor ineach case, but such always bears an individual stamp. 
 We must not forget that while the limit values of every function 
 have a scientific meaning, the conditions met in actual practice are 
 different. Science calls an individual blind only when perception 
 of light has entirely disappeared, but in actual practice, he is blind 
 if the faculty of sight has been weakened to such an extent that
 
 34 ECONOMIC MEANING OF BLINDNESS. 
 
 the organ of Aision cannot be used to earn a living (Magnus 24); 
 The meaning of blindness as used in daily life is much narrower 
 than that of science. 
 
 Xow and then extremely great demands may be made upon 
 the action of certain organs which may reach to its highest ability. 
 Jn actual practice we are satisfied with the amount of labor which 
 does not strain the powers. Zehender's (53, p. 266) principle, that 
 the full earning ability existed only Avith full acuity of 
 vision and every diminution of the highest limits means 
 at the same time a diminution of the earning ability, 
 cannot be accepted. Xot alone do we raise scientific 
 scruples against the acceptance of a proportional relation be- 
 tween the earning ability and the scientific meaning of visual 
 acuit}', but also practical experience is entirely against such rela- 
 tion. There is hardly any vocation Avhich demands the extreme 
 limit of sight (according to scientific figures), as a condition of 
 success. In each vocation a great many individuals may be found 
 who have comparatively poor sight but the same earning ability 
 as those with normal eyes (Groenouw 11). Josten (20, p. 526) is 
 correct when he says that Zehender shifted with his principle not 
 alone the limits of the earning ability, but created a new and arti- 
 ficial meaning. Neither the lowest nor the highest points of sci- 
 entific visual acuity correspond with that used in business; the 
 lowest point of the latter is not as low as the lowest point laid 
 down by science, while the highest point of the functional range 
 that may be regarded as normal, must be considered greatly below 
 the highest scientific limit. The highest as well as the lowest de- 
 mands of the different professions upon the central acuity differ 
 greatly and we have no proper standard for their exact numerical 
 estimation. 
 
 Groenouw has proposed that it would be suitable to gather exact 
 observations concerning the minimum of visual acuity sufficient for 
 a certain vocation by examining the vision of workingmen in differ- 
 ent factories and comparing the same with the work done on the 
 wages earned. We would certainly gain a knowledge of what 
 functional qualification may be necessary in a certain trade, but 
 we do not believe that we can gain an exact knowledge of the lowest 
 demands of the different professions upon the ocular functions, as 
 we can only find out by such examinations the case which has the 
 lowest vision and how high is the earning value of this vision. So 
 that, if among the personnel of a certain trade one workman with 
 a visual acuity of ^/^ has been al)le to earn a living, it may be possi- 
 ble that in the workmen of another factory a still lower acuity of 
 vision, even ^ , may have allowed a certain individual to earn a 
 living. But. if by exhausting the complete examinations of large 
 numbers, we have eliminated the probability of finding lower values, 
 even this might not preclude the possibility of finding the very low^ 
 est degree of vision which is sufficient for this particular trade.
 
 ECONOMIC LIMITATIONS OF VISUAL ACUITY. 35 
 
 kind of work the individual may follow-. In the case of a day 
 laborer whose visual functions are not much taxed in his work, the 
 sudden reduction of whose vision to lo the normal would probably 
 not prevent his working, but if the vision of a skilled mechanic 
 should suddenly be reduced to 1/2, he will certainly have to stop, as 
 lie is used to work with clear retinal impressions. In acknowledg- 
 ment of these conditions, the courts have lately given opinions in 
 which the demands of the particular professions have been consid- 
 •ered. The German Imperial Insurance office (3, p. 250) seems to 
 favor such principles. 
 
 Considering the above, it is advisable to give movable boundaries to 
 the economic limitations of vision. Letus accept the maximum limits 
 as between •% and 3^ of the normal scientific standard for the visual 
 acuit}' and in the following our estimations will be made with these 
 two values. The loAvest professional limit of visual acuity is not in 
 concurrence with the minimum scientific limit, for when the acuity 
 of vision sufficient for working purposes has ended, there still re- 
 mains an acuity that may be judged by the scientific standard. 
 Zehender's proposition (53, p. 268), where he considers the lowest 
 limit value of the professional acuity as Moo of the normal scien- 
 tific value of vision, cannot be supported. Professional work is 
 impossible with only Moo of the normal visual acuity. "We would 
 regard even a far higher degree of acuity as too low and believe that 
 a standard for complete inability to earn should be fixed at Mo 
 •of the normal visual acuity. In many cases even this limit of Mo 
 would be too low, because there are vocations in which a higher 
 limit than V20 would be insufficient. Silex (39 separate edition, 
 p. 6) thinks that in certain branches of the railroad serAice and in 
 •certain other trades or professions a visual acuity below Ve would 
 be insufficient. It is, therefore, advisable to make the lowest eco- 
 nomic limit of visual acuity a movable one and not to fix an un- 
 changeable value. We therefore adopt for the lowest economic 
 limit of the visual acuity two values, 0.05 ( Mo) and the standard 
 of Silex, 0.15 (about M or M of the normal visual acuity). 
 
 Out of these four limit values the two maximums (0.75 and 
 0.5) and the two minimums (0.15 and 0.05), we may construct two 
 ranges within which the professional or economic limits may lie. 
 One of these spheres or ranges would have as its highest limit 0.75 
 (Mi), as the lowest 0.15 (about Mr), while the other range would 
 be between 0.5 ( M ) and 0.05 ( Mo) of the normal scientific stan- 
 dard for visual acuity. It is not necessary that the said maximum 
 and minimum limit values exist in both eyes; it is sufficient that 
 they be shown in one eye, the other having a lesser acuity than that 
 which we have declared as absolutely necessary for professional 
 optic demands. We believe that if the second eye in trades having 
 higher visual demands, retains an accuracy of vision of M , and in 
 those having lesser demands, M • we may speak, in a professional 
 sense, of "sufficient visual acuitv."'
 
 36 ECONOMIC LIMITATIONS OF VISUAL ACUITY. 
 
 The least acuity of Adsion found would only demonstrate with what 
 small degree oi vision an individual could learn a trade or by long 
 practice be able to follow it, but it could not show how low the 
 visual acuity of a former normal person might suddenly depreciate 
 without making him unfit for his trade. Any one entering a pro- 
 fession while young with a certain amount of defective vision may 
 gain by practice full earning powers. The highly characteristic 
 examples given by Groenouw (11) show how much weakness of 
 vision acquired in youth may exist without marring the earning 
 capacity. 
 
 There is quite a difEerence, hoAvever, in the case of a person, 
 starting to learn a trade, having congenital \X)ov sight or acquiring 
 it in earl}' youth, and therefore used to indistinct pictures on the 
 retina, and a case of a man with normal vision, accustomed to Avork 
 with clear retinal pictures, who, after an accident, may have to 
 suddenh' depend upon indistinct visual impressions. The same 
 degree of vision sufficient in the former case Avould not be enough 
 for the latter. It is, of course, possible that in the latter case,^ 
 long continued practice might finally lead to sufficient recovery of 
 the earning ability and the degree of visual acuity here existent 
 might be considered as the least compatable Avith the profession. 
 But such a rule could not be made general. For the recovery of a 
 certain degree of the earning ability after diminution of the visual 
 acuity is not dependent u]X>n the Avill of the individual, but upon 
 other decisiA-e factors. The age of the individual plays an im- 
 portant role in this ultimate comi>ensation. A younger man may 
 easily OA-crcome a high degree of disturbed vision and by practice 
 rec-over the lost earning poAver; but in an older individual even a 
 lesser degree of visual disturbance AA'ill never be overcome. Any 
 intellectually gifted individual AA'ill be able to make use of indis- 
 tinct retinal impressions in his work to a far greater extent than 
 an intellectually dull one. The above factors shoAv that a certain 
 degree of visual acuity Avould be sufficient in one person for a cer- 
 tain vocation, AA'hile another could not Avork by it. 
 
 Although exact figures as to the limits of the Avorking acuity 
 cannot be found by examination of patients, yet certain estimafions 
 may be made from experience. Josten (19b, p. 528) refers to the 
 A'isual limits acceptable for military service. The instructions for 
 military service (8, p. 96) designate a diminished visual acuity to 
 ^2 of the normal as, "a small disalulity which does not destroy 
 the general fitness." A Ansual acuity in both eyes that is betAveen 
 /^ and M 1^5 called "conditional"; and if it is Vi or below, it i& 
 called "absolute unfitness." Josten (19 b, p. 528) adopts the mili- 
 tary standard to business life as folloAvs : "Diminution of the 
 earning ability does not take place if there is 3^ the normal visual 
 acuity in both eyes." But, although this proposition of Josten is 
 very simple and acceptable, yet in certain cases a shifting of the 
 visual standard above 3^ is necessary. This depends upon the
 
 TABLE OF TRADES SHOWING VISUAL DEMANDS. 37 
 
 According to this standard we submit tables which divide the 
 followers of the different manufacturing vocations into two groups : 
 
 TABLE A. 
 
 THE VARIOUS TPxADES AND PROFESSIONS ARRANGED ACCORDING TO 
 THEIR VISUAL DEMANDS. 
 
 GROUP I. 
 
 Trades requiring liigher degrees of visual acuity. Range 0.75 to 
 0.15 (scientific standard). 
 
 The higher professions. 
 
 Medicine. 
 
 Theology, 
 
 Law. 
 
 Art. 
 
 Engineering. 
 
 Students of all professions. 
 
 Fine mechanics. 
 
 Iron and steel workers. 
 
 Eolling mill workers. 
 
 Machinists and metal workers. 
 
 Precious metal workers. 
 
 Musical instrument makers. 
 
 The linen industry. 
 
 The textile industry. 
 
 The silk industry. 
 
 Paper workers. 
 
 Leather workers. 
 
 Garment makers. 
 
 Printers. 
 
 Marine employees. 
 
 Railway and steamship employees (including city roads). 
 
 Soldiers and sailors. 
 
 Telegraph operators. 
 
 Skilled labor generall}^ 
 
 GROUP 11. 
 
 Trades requiring lower degrees of visual acuiig. Range 0.50 to 
 0.05 (scientific standard). 
 
 Glass blowers. 
 
 Mine workers. 
 
 Quarry men. 
 
 Builders. 
 
 Pottery makers. 
 
 Brick makers. 
 
 Workers in mechanical industries. 
 
 Employees in gas and water works.
 
 38 DIFFERENT' VISUAL DEMANDS IN TRADES. 
 
 Paper makers. 
 
 Wood workers. 
 
 Mill empIoA'ces. 
 
 Manufacturers of food articles. 
 
 Sugar factory employes. 
 
 Brewers and maltsters. 
 
 Tobacco workers. 
 
 Chimney sweeps. 
 
 Street railway employees (horse cars). 
 
 Employees of elevators and Avine cellars. 
 
 Teamsters. 
 
 Bargemen on inland waters (rivers, etc.). 
 
 Farmers, etc. 
 
 Day laborers, etc. 
 
 Unskilled labor generally. 
 
 Individual members of certain trades do not have exactly the 
 same visual demands made upon them; some under certain cir- 
 cumstances may have much higher and others lower visual 
 requirements. In the course of our work, in certain cases, 
 we must remember this fact and not judge all the members of the 
 some trade by the same standard. The railroad employees have 
 been officially divided into fixed classes, and if the other trades 
 could be so treated, the physician would know exactly into what 
 class he should put the individual case. We do not desire to force 
 our propositions upon the associations, physicians or officials. . We 
 desire, however, that the foregoing shall be considered before gen- 
 erally adopted principles be introduced into practice. It is cer- 
 tainly advisable to reach some definite agreement as soon as possi- 
 ble, as liitherto there has been a disposition among oculists to 
 consider only the results of the scientific examination of the visual 
 acuity as the basis for the valuation of the conditions arising in 
 practical life. If the estimation of the result of the amount of 
 damage arising from ocular injuries is to be made in a just man- 
 ner according to actual conditions, this custom must be abandoned. 
 
 Our views regarding the difference between the scientific and 
 working standards of visual acuity can claim far more extensive 
 practical consideration than that which relates alone to the sub- 
 ject in hand of ocular injuries (Chapter XIX). All profes- 
 sions or vocations which make admission dependent upon a certain 
 degree of vision would do well to remember that practical visual 
 acuity and that of scientific standard are entirely different things 
 and that an individual may have, for working purposes, a full 
 amount of vision who by the scientific standard shows a deficit. 
 This fact has been ignored in the past, it being considered that an 
 individual with defective visual acuity according to the scientific 
 standard must have the same defect in his working life. Individu- 
 als have been refused admittance to trades on ocular grounds, al-
 
 CLASSIFICATION OF RAILROAD EMPLOYEES. 39 
 
 though if their vision had been measured according to the economic 
 and not by the scientific standard, they could have pursued their 
 vocations. The authors have many times seen how much at vari- 
 ance the purely scientific examination of the visual acuity could 
 be with the demands made by practical work. The management 
 of the German roads have lately taken this into consideration,. 
 Magnus' suggestions having been accepted since January 1, 1893, in 
 the Breslau Eailroad Company as regards the qualifications of 
 railroad employees. Their requirements do not now include "nor- 
 mal" acuity of vision by the ''scientific standard," but only "suffi- 
 cient visual acuity/' the authorities having thus acknowledged that 
 an estimation of the vision required in railroad employes should 
 be made by the practical economic or professional standard rather 
 than that of the scientific. Schmoeckel (36) and Silex (39) have 
 lately divided the employees of railways into two classes similar to 
 our proposition. In these, one eye is to have at least -^^ (Schmoec- 
 kel) or ^ (Silex) and the other /4 ; and in the other class one 
 eye must have at least ^ (Schmoeckel) or 3^2 (Silex) and the- 
 other 3^ or 3^ of the normal visual acuity. Schmoeckel thus 
 divides the different branches of railway employes according to the 
 visual demands made upon them, into the following groups : 
 
 Group I. — Without glasses on one eye at least a visual acuity 
 of 5^ , on the other l^ of the scientific standard : Locomotive em- 
 ployees (engineers and firemen), station employees, switchmen,, 
 flagmen, yardmen. 
 
 Group II. — With or without glasses on one eye at least a visual 
 acuity of 3^ and on the other 3^3 of the scientific standard: 
 Wipers, wagonmasters, brakemen, guards, conductors, baggage- 
 masters, warehousekeepers, freightmasters, porters, watchmen, des- 
 patchers, roadmasters. 
 
 The two groups proposed by Silex contain about the same di- 
 visions, only he puts brakemen into Group I., whereas they are put 
 into the second group by Schmoeckel. 
 
 In America the tendency is to demand the highest visual quali- 
 fications from prospective railway employes, the full scientific stan- 
 dard of -%x (1-0) being required by many railroads and being 
 demanded as essential by the consulting oculists of the principal 
 systems. It must, however, be observed that what we call normal 
 visual acuity is a very relative term, so that ^%x, the usual 
 standard, may in a good light be read by a young person with re- 
 duced visual acuity, when his real economic standard is -%v , or 
 2% (Thomson 45, p. 349). 
 
 Allport (1) recently inquired into the conditions existent in 
 the United States relative to the vision required of railroad em- 
 ployes, and in response t« a circular letter received specific answers
 
 40 VISUAL RAILROAD REQUIREMENTS IX THE UNITED STATES 
 
 from 64 railroads operating 90,950 miles of road; there being 244 
 prominent railroad companies in the United States which cover 
 205,638 miles of road. Fifty-three out of 64 roads exacted systematic 
 eye and ear examinations, about 50 per cent, requiring such examina- 
 tions of all men directly engaged in moving and operating trains, 
 in giving and receiving signals, such as engineers, firemen, con- 
 ductors, brakemen, j^ardmen. signalmen, switchmen, etc. This 
 examination is made by a railway employee, such as the superin- 
 tendent, trainmaster, etc., and doubtful cases are sent to the eye 
 and ear surgeon. Nine roads have a regularly employed oculist. 
 In three the men are examined by the railway surgeon, and doubt- 
 ful cases are referred to an oculist. In three the examinations are 
 made by surgeons of Railway Eelief Associations. The standard re- 
 quired is various. In 23 it is claimed that "perfect eyes" are re- 
 quired of both old and new employees. In 16 perfection is required 
 in new men and reasonable concessions made to old employees. In 
 one road engineers and firemen must possess of ^^x in one eye 
 and 2^xx in the other; conductors, flagmen, brakemen, switch- 
 men, must have a vision of -%xx in one eye and ^y^-L in the 
 other; all others must have ^o^^^ in both eyes. One road demands 
 75 per cent, of the normal function, etc. This shows that the' 
 scientific standards required are decidedly different. We are, how- 
 ever, fast coming to the conclusion that a practically perfect U'ork- 
 ing or economic standard of visioti should be required for new men 
 and that they should not have any grade of refractive error, such 
 as hyperopia over 2.5 D, which would ultimately render their 
 distant vision poor, as owing to the dust and exposure of railway 
 service, the vision should be normal without the correction of any 
 refractive error by glasses. 
 
 Allport (1) divides the railway employees into two classes ac- 
 cording to their specific vocations. 
 
 Class A. — In which the vision is required to be at least ^%xx 
 in one eye and ^^l in the other, and which must be reached 
 without glasses; distance glasses are not allowed on duty. 
 
 Class B. — In which the vision shall be at least ^/^l in one 
 eye and 20^ in the other, and in which the employee is not only 
 allowed to wear glasses, but is required to do so if the refractive 
 error is such that it is necessary to bring vision up to the proper 
 standard- 
 
 Class A. — Engineers, firemen, conductors, brakemen, switch- 
 men, signalmen, switch-tenders and engine-dispatchers. 
 
 Class B. — Track foremen, bridge foremen, crossing flagmen, 
 bridge tenders, gatemen, train baggagemen, telegraph operators, 
 station agents and station baggagemen. 
 
 Williams (48) makes about the same subdivision of the classes 
 and demands the following;:
 
 ADVISABILITY OF GEXERAL AGREEMENT FOR VISUAL REQUIREMENTS. 41 
 
 Class A. — Engineers, firemen. For entrance to the service or 
 promotion, ^^x or average normal vision in each eye, re-exam- 
 ination every three years not less than ^%xx '"'ith both eyes 
 open without glasses. 
 
 Class B. — For entrance to the service or promotion -/^x in 
 one eye and not less than ^/^l in the other and for re-examina- 
 tion every three years not less than ^^^l with both eyes open with- 
 out glasses. 
 
 Thus in Germany the application of the full scientific stan- 
 dard to the eases of railway employees has been abandoned and 
 visual acuity of ^ or ^ is regarded as sufficiently high, and, 
 therefore, we may consider this quantity as the normal economic 
 standard or 1.0. As these considerations will be ultimately ac- 
 cepted, it is perhaps advisable to adapt our test letters to the pro- 
 fessional standard. This may be easily done on the examination 
 cards now in use, if we would mark the lines on Jager's types or 
 Snellen's cards (see Plates II., III.), which are equivalent to ^ 
 or ^ of the scientific standard as the full professional acuity for 
 the higher trades and ^ or ^ that for trades demanding less 
 visual acuity. The German Ministry of Railroads (38) has lately 
 divided its employees into dilferent classes as regards their visual 
 demands and has therewith given the examining physician a basis 
 for judgment of the ocular earning ability in the individual case. 
 It would be desirable that the Accident Insurance Companies and 
 Railroads of America and the managements of other vocations de- 
 manding specific visual qualifications, would do the same thing with 
 all applicants. 
 
 When we have thus placed the meaning of economic visual 
 acuity within materially narrower limits than that which the sci- 
 ence of ophthalmology permits, we must not forget that our charts 
 used for estimation of the visual acuity correspond only with the 
 scientific standard. Thus in each case the remaining degree of 
 visual acuity according to the scientific standard found by the 
 physician in the case of the injured person should be transposed 
 into that of the economic standard before it may be used for esti- 
 mating the damage to the earning ability. This is done in the 
 following table :
 
 42 
 
 CONVERSIOX OF VISUAL STANDARDS. 
 
 TABLE B. 
 
 THE SCIENTIFIC STANDARD FOR VISUAL ACUITY CONVERTED INTO 
 ECONOMIC TERMS. 
 
 II. 
 
 Scientjtic 
 standard. 
 
 Econoniif 
 vocations 
 
 standard for 
 demanding 
 
 Scientifle 
 standard. 
 
 
 Kconodiir 
 vocations 
 
 standard for 
 demanding 
 
 
 lii^he 
 
 - degrees. 
 
 
 
 lesse 
 
 - de^^rees. 
 
 0.75 = 
 
 1 
 
 
 
 0.50 
 
 = 
 
 1 
 
 
 0.70 = 
 
 0,9166.. 
 
 = 
 
 ^Mo 
 
 0.45 
 
 = 
 
 0.8888.. 
 
 = ^ 
 
 0.65 = 
 
 0,8333.. 
 
 = 
 
 '%2 
 
 0.40 
 
 = 
 
 0.7777.. 
 
 = V9 
 
 0.60 = 
 
 0,750 .. 
 
 == 
 
 M2 
 
 0.35 
 
 = 
 
 0.6666.. 
 
 = Y^ 
 
 0.55 = 
 
 0,6666.. 
 
 = 
 
 yi2 
 
 0.30 
 
 = 
 
 0.5555.. 
 
 = V^ 
 
 0.50 = 
 
 0,5833... 
 
 = 
 
 M2 
 
 0.25 
 
 = 
 
 0.4444.. 
 
 = y^ 
 
 0.45 = 
 
 0,500 ... 
 
 = 
 
 /12 
 
 0.20 
 
 = 
 
 0.3333.. 
 
 = H 
 
 0.40 = 
 
 0,4166... 
 
 = 
 
 yi2 
 
 0.15 
 
 = 
 
 0.2222.. 
 
 = ^ 
 
 0.35 = 
 
 0,3333... 
 
 = 
 
 yi2 
 
 0.10 
 
 = 
 
 0.1111.. 
 
 = H 
 
 0.30 = 
 
 0,250 ... 
 
 = 
 
 M2 
 
 0.05 
 
 = 
 
 0.000 
 
 
 0.25 == 
 
 0,1666... 
 
 = 
 
 M2 
 
 
 
 
 
 0.20 = 
 
 0,0833... 
 
 = 
 
 M2 
 
 
 
 
 
 0.15 = 
 
 0,000 
 
 
 
 
 
 
 
 In tables which follow, by which the state of the earning 
 ability in cases of different ocular injuries is estimated, the calcu- 
 lation is always based upon the values altered as above, but 
 as this valuation is not yet generally accepted and the fixing 
 of the acuity of vision is generally done according to the method 
 of Snellen, we have also given the degrees according to scien- 
 tific standard. It must be remembered that in all our tables the 
 amounts of visual acuity correspond with the scientific values 
 transformed as above into the professional ones. Thus with visual 
 acuity of 0.4, its economic value is not 0.40 but 0.7777 . . , if the 
 injured person has a profession with slight visual demands; but 
 if it requires a higher degree of vision, the scientific standard 
 of visual acuity, 0.4, would be transformed into 0.4166 . . , with 
 which the calculation is made. 
 
 We show, figuratively, the relations between the scientific and 
 the economic visual acuities in Plate I. (Frontispiece). In this 
 drawing the degrees of vision in the absciss and the ordinate axis 
 are marked, at intervals of 0.01, so that five of these are always taken 
 together; the absciss as well as the ordinate axis are divided by this 
 into 20 equal parts. The curve of the scientific visual acuity is 
 marked as a coarse black line d) and because this progresses gradu- 
 ally, it has been equally divided. Economic vision will not suffer 
 very much if the acuity falls off 0.05, because the difference 
 between 1 and 0.95 is so little that it will scarcely be noticed. But, 
 if the acuity falls off further, a point will soon be reached where
 
 ECONOMIC LIMITS OF VISUAL FIELD. 43 
 
 every loss affects the working capacitj'^, and if the vision falls be- 
 low this point, for instance, to 0.005, tlien it has no economic value 
 whatever, and when it reaches this lowest point and further de- 
 preciates, vision will be professionally of no importance. Corres- 
 ponding with these facts, the two curves of the economic visual 
 acuities should not be marked as grades ; the beginning and end of 
 the curves should deviate, as we have shown, but these deviations 
 are so little that we have divided them similarly to that of the scien- 
 tific standard. The fine line (II) shows the course of economic 
 vision for higher, and the broken (III) line for trades having lesser 
 visual demands. As the drawing shows, both curves start together 
 with the absciss-axis, and then when the climax of the demands is 
 reached, they run parallel. 
 
 We have also evolved test types corresponding to those of 
 Jager for proximal vision and to Snellen's for distant vision (see 
 Plates II and III). The ordinary Snellen test cards may be used 
 in the same way by reducing the scientific standards to economic 
 terms. 
 
 §13. The Economic Limits of the Visual Field and their Estima- 
 tion. 
 
 The limits of peripheric vision are to be regarded from either 
 a scientific or an economic standpoint, and as has been shown in 
 discussing the visual acuity are quite different. Peripheric limita- 
 tions or even greater defects of the field of vision, if only in one 
 eye, and under certain circumstances, a moderate limitation of the 
 visual fields of both eyes, will not impair their earning capacity. We 
 would only regard limitation of the field of vision as entitled to 
 an indemnification, if the limits for white in the binocular field are 
 temporal 70°, superior 40°, inferior 60° ; and in the monocular 
 type, temporal 70°, nasal 45°, superior 40°, inferior 65°. This 
 corresponds to those limitations which Haab (15, Table I., figure 
 la) adopts as the narrowest ones admissible under normal condi- 
 tions. The suggestion of Schroeter (37, p. 16) is very useful in 
 estimating the amount of economic damage to the field of vision. 
 Therefore, like Schroeter, we divide the binocular field into three 
 zones of 30° each: the first from the outermost periphery to 60°, 
 the second from 60° to 30°, and the third from 30° to the point of 
 fixation (Plate IV., figure 1). It is evident that these three zones 
 do not have the same value functionally; the inner one has the 
 most, the outer the least, but nevertheless as it complicates the 
 subject too much we do not give them a different value like 
 Schroeter does. We are of the opinion that the functional differ- 
 ences of these zones can hardly render itself felt economically, for 
 the outermost zone of the field of vision represents a much greater 
 range of the retina than the central, and the intermediate one 
 represents a greater range than the inner one. But what the outer 
 zone lacks in functional ability compared with the two others, it
 
 44 ECONOMIC LIMITS OF MUSCLES. 
 
 makes up by its greater extent, so that for practical use the ex- 
 tent of the different zones is compensated for by the relative differ- 
 ence in the functional ability; therefore we give each of these 
 zones the same value. The entire binocular field of vision P, would 
 be composed of three factors of equal value. According to this all 
 defects of the field of vision could be given their numerical valua- 
 tion, for instance, with the loss of one eye we would lose I/q of the 
 binocular field, with a homonymous hemianopsia f^e, etc. In 
 paragraph 11 we have noted the reasons for introducing the visual 
 field as a root value into the formula for the visual act. 
 
 §14. The Economic Relations of the Ocular Musculature and 
 their Estimation. 
 
 The outer ocular muscles have their peculiar relations to the 
 earning power. In view of the fact that the binocular act of 
 vision in its earning relations may only be regarded as preserved if 
 all the ocular muscles be unimpaired, the functional disturbance of 
 one single ocular muscle is a bad one, because with the paralysis of 
 one muscle diplopia appears and immediately suspends the binocu- 
 lar act, causing thereby complete exclusion of the affected eye. 
 Therefore, if both eyes are functional and the act of vision was 
 binocular, a paralysis of one ocular muscle should be regarded 
 from an economic standpoint in the same light as the complete 
 loss of one eye, and the diminution of the earning ability 
 must be the same as the loss of one eye, even if it 
 be only temporary. Less consideration should be claimed 
 for the loss of the function of one ocular muscle if the 
 act were previously monocular. In such a case the loss of one 
 muscle is only- an inconvenience or may be termed a small injury. 
 We regard the action of the outer ocular musculature as a sum of 
 different muscular actions, corresponding with the number of the 
 outer muscles, which makes a sum of six individual functions. 
 By omitting one muscle, the muscular action will appear in the 
 formula for the act of vision as a fraction, ^ . The fact that the 
 six outer muscles of the 63^6 are not of the same relative value for 
 the earning capacity has also to be considered. Quite different 
 demands are made by certain vocations ; for instance, in the case 
 of miners, the rectus superior is particularly needed (N'ieden 31), 
 while in other trades it is but little used. In all factors demanding 
 clear vision in the distance, as that of sailors, the rectus externus 
 is more used than in those professions whose work is near the eye ; 
 in the latter the rectus internus is the most prominent muscle and 
 for general use we think that the internal rectus should be given 
 the most prominent place as regards the earning capacity. This 
 varying value of the outer ocular muscles in the difPerent pro''es=ions 
 makes the valuation somewhat difficult; for, if we gauge the mus- 
 cles by the standard put for one certain vocation, we would make a
 
 THE INTRINSIC MUSCLES. 45 
 
 mistake. For instance, if we give the valuation to the rectus 
 superior that is needed in the case of a miner, it would be over- 
 valuation f oi' most of the other professions and an under-valuation 
 of the other muscles. It is, therefore, for ordinary purposes, neces- 
 sary to regard the outer ocular muscles as of equal value and to 
 give each ^ of the total. But in special cases we can do justice to 
 the demands of the different professions and when necessary value 
 them higher, for instance, 5^ or /^ . We have deemed it necessary 
 to introduce the muscular action as a root value m the full formula 
 for the act of vision (§ 11, p. 30.) 
 
 In only exceptional cases could injuries of the intrinsic muscles 
 (affecting the accommodation or the pupil) have any special in- 
 fluence upon the earning ability, because, by the use of suitable 
 convex glasses, the derangement may be overcome.
 
 46 THE ABILITY TO COMPETE. 
 
 CHAPTER Vn. 
 
 §15. The Meaning and Estimation of the Ability to Compete. 
 (K of our formula for the earning ability.) 
 
 As we have explained in Chapter IV. the ability to compete is 
 one of the three factors composing the full earning ability. We 
 have shown that this is the least valuable of the three and that it 
 should be inserted into the formula with a smaller value than the 
 other factors. We will make a few remarks regarding the position 
 this factor takes in the estimation of the injury to the ocular earn- 
 ing ability. 
 
 When an individual receives an accidental injury, especially 
 that of vision, the damage to him is a double one. First, there is 
 the impairment of his working ability from the results of the acci- 
 dent in that he cannot perform as good or as much work as for- 
 merly, and second his chances for obtaining work quickly and 
 easily are less. This second factor is not so unessential as one 
 might suppose. Practical experience shows that the one-eyed per- 
 son not only has more difficulty in finding employment, but that 
 in some factories his visual disorder makes it difficult for him to 
 retain his employment. Workmen with sound eyes are preferred 
 by most employers of labor and from their standpoint, certainly 
 not without reason. The injured person, therefore, has a right to 
 claim not alone a compensation for the impairment of his capacity 
 for work but also the difficulty which he encounters in making the 
 most of this capacity. Therefore, in estimating the impairment 
 of the earning ability, we have always and under all circumstances 
 to consider the diminution of the ability to compete. 
 
 The ability to compete is a conception resulting from a com- 
 bination of heterogenic elements of which a part lies in the indi- 
 vidual himself and is affected by the condition of his health, his 
 knowledge, etc., while another portion is beyond his control. It is 
 this latter element the world values in judging the ability of the 
 individual. The ability to compete in the labor market, the possi- 
 bility of finding employment, is fixed, therefore, by the physical and 
 mental ability of the individual as well as by the way others judge 
 of it. If we apply this reasoning to the organ of vision, the ability 
 to compete of each individual will depend firstly upon the ability 
 of the visual organ and secondly upon the way others are judging 
 its condition; an example should render this clear. Supposing 
 some one has suffered an injury to one eye and seeks employment, 
 his chances of obtaining the desired work will depend first, upon 
 his visual powers and secondly, upon the way the employer judges
 
 THE ABILITY TO COMPETE. 47 
 
 them. The employer will be willing to give or refuse work to this 
 particular individual according to how he regards the injury of the 
 eye as detrimental for the performance of Ms particular work. If 
 we desire to state the ability as a numerical quantity, we must con- 
 sider such conditions, which we think we can do by the following: 
 
 The Part of tiie Ability to Compete That Each Indi- 
 vidual Supplies by Himself, in our case the ability of his organ 
 of vision, we bring forward into the formula under normal con- 
 ditions when we insert the expression for the normal act of vision, 
 
 1 
 
 C V F V M, but in the case of accidents the impaired value of the 
 act of vision should be put in as the lowest value in the root. In 
 Chap. IV, § 9. we have given the reasons for accepting the ability to 
 compete as the lowest value and we have likewise shown that the 
 ability to compete is of less value in the formula for the earning 
 ability E than the other factors, i. e., it has a smaller influence upon 
 the value of E than the others. We have, therefore, adopted the 
 ability to compete K as a root value. For, if K be reduced by an 
 impairing of the act of vision, it becomes a proper fraction, for in- 
 
 K 
 stanc^, . ISTow the root of a proper fraction is always greater 
 
 Z . " . . 
 
 than the fraction itself; the value of K. after the impairment if it 
 
 \r 
 
 is taken as a root vahie can not any more l)e but it must be 
 
 2K ^ 
 
 greater, for instance, - . By taking K as a root, its value, in the 
 
 case of a visual impairment, is greater than it would have been if 
 K without root would have been taken into the calculation. And 
 as the amount of the earning ability is directly fixed by the 
 amount of the ability to complete, K exercises less influence upon 
 the earning ability than the other factors, as soon as we insert K as 
 root in the formula for the earning ability. The full formula 
 
 being: f^ = V ^^^^^ 
 
 The Part of the Ability to Compete Not Depending Upon 
 the Individual, in Our Case Not Upon the Condition of the 
 Eyes, but Upon the JuDorENT of the Employer, we ren- 
 der by the exponent of the root which we chose for K; taking 
 
 K 
 a small exponent the value of will be enhanced to a less extent 
 
 and if we take a large exponent to a higher extent. If we enhance 
 the value of the ability to compete by taking a greater root ex- 
 ponent, as the earning ability increases as much as the ability to 
 compete becomes greater, the earning ability will he. greater accord- 
 ing to the size of the root exponent. If we would indicate that the 
 employer regards a certain ocular impairment as an iuiportant di- 
 minishment of the working cajisicity we would take a smaller ex- 
 ponent, but if we intend to show that an ocular impairment is of
 
 48 ELASTICITY OF OUR METHODS. 
 
 less importance to the employer, avc would take a greater one. We, 
 therefore, choose for all slight and moderate visual impairments 
 a different root exponent than for tlic serious ones; therefore, for 
 the slight impairments we give the ability to compete the root ex- 
 ponent 10, but if the impairment of central vision is serious, i. e., 
 in the case of professions with higher visual demands if it falls be- 
 low 0.15 and in those with less demands below 0.05, and instead of 
 the root exponent 10 we take the exponent 5 for these professions 
 with greater visual demands and the exponent 7 for those with less. 
 The same is to be done in the case of the complete loss of one eye 
 or in the case of the loss of the eveball. If we think that the aes- 
 thetic dilferences between simple blindness of the scientilic standard 
 without injury to the looks of the eye and the loss of the eyeball, or, 
 for instance, the formation of a bad looking eye, as leucoma or 
 staphyloma are greater, we may give expression to our opinion by 
 choosing a great root exponent for the ability to compete in the case 
 of simple blindness without deformity. By leaving the selection 
 of the root exponent to the judgment of the calculator, sufficient 
 room is given for the individual conception of each case; thus our 
 formula adapts itself to the peculiarities of the individual case and 
 to the judgment of the physician, avoiding thereby a rigid form and 
 doing justice to both parties. Therefore, in forming a special esti- 
 mation of the ability to compete we first fix the amount of the 
 injury to the act of vision in each case, and upon this depends that 
 part of the ability to compete which the individual furnishes him- 
 self. As regards the second part, in certain cases it will be found 
 that while there is no or but little actual injury to the visual sense 
 itself, yet certain injuries of the eye disturb the relations of the 
 individual to the employer. 
 
 Such a case as the following is often experienced in practice: 
 A man has his cornea burned by lime which leads to the formation 
 of leucoma and diminishes the visual acuity of that eye to 0.25 of 
 the normal, the other eye remaining well. Thus, although such an 
 individual is not optically impaired for his work because the normal 
 eye allows the undisturbed following of his trade, the chances of his 
 finding work have become less. A great many employers would 
 hesitate to take into their service a man with a bad looking eye, 
 who shows so plainly the effects of the injury or who, he knows, 
 can see normally only with one eye; in spite of the fact that in such 
 a case an actual impairment has not taken place the ability to com- 
 pete is certainly diminished. We are consequently in the peculiar 
 position of estimating an ocular impairment of the abilitv to com- 
 pete when there is no real defect of working vision. Thus we think 
 we can meet these difficult conditions in the best manner if we ex- 
 press the diminution of the ability to compete in all cases by the 
 arithmetical proportion of the visual acuity of both eyes. The 
 ability to compete is in fact a quantity which is almost identical 
 with the act of vision but not dependent upon it as the maximum
 
 IMPAIRMENT OF ABILITY TO COMPETE. 49 
 
 of the visual acuity in both eyes. In our example we suppose that 
 the vision of one eye remains normal while that of the other was 
 diminished to 0.25, consequently the numerical expression for the 
 ability to compete would be : 
 
 r 
 
 1 + 0,25 
 
 V F V (mi ma m., m* m.^ ms) (mi" m/ m/ m/ m/ m/) 
 
 The reasons for expressing the impairment of the ability to 
 compete by the arithmetical proportion of the central acuities of 
 both eyes are the following : Even if a diminishment of the binocular 
 acuity of vision cannot be proven scientifically where one eye is 
 alone affected, professionally the binocular vision has not the same 
 value as formerly. If we unite the normal vision of the one eye 
 and the impaired one of the other by the mathematical expression 
 of the arithmetical proportion, the value of the normal acuity will 
 be diminished by the size of the injury to the other eye; we then 
 use this arithmetical proportion as the root value with the exponent 
 10 and thus provide that the normal vision is but slightly reduced 
 by the impairment of the vision in the other eye. By this means 
 the practical conditions may be satisfactorily considered. If one 
 of the other factors entering into the economic act of vision be im- 
 paired, for instance, the peripheric vision, while all the other fac- 
 tors as well as the central acuity remain untouched, the impairment 
 of the factor in question should be used in such a manner that we 
 first insert it into the expression for the normal act of vision as 
 the tenth root in the calculation. For instance, from an accident 
 only the field of vision has suffered and if it is only two-thirds of 
 its original range while the central acuity and the muscles remain 
 imchanged, we enter into the formula for the normal professional 
 act of vision for the field of vision P the value two-thirds. The 
 formula for the ability to compete would thus be: 
 
 y 
 
 ex K % P K (mi m. m:! m^ m.^ mfi) (m/ m./ m/ m/ ms' m/) 
 
 If several of the factors be damaged at the same time, the 
 amount of such damage has to be inserted into the formula as the 
 xth root. For instance, the central acuity of vision in both eyes 
 diminishes to 0.30 (scientific value), while the field of vision be 
 limited to one-third, these values for the acuity and the field would 
 have to be first entered into the formula of the working act as an 
 arithmetical proportion, being changed correspondingly while the 
 numerical value of the muscular action would remain the same, the 
 formula then would be : 
 
 X 
 
 f 
 
 0,30 + 0,30 
 
 2 VV^ P / (mi mo m:, m4 m-, mr.) (m/ mo' m/ m/ mr,' m/)
 
 50 USE OF DIFFERENT ROOT EXPONENTS. 
 
 and if we enter this below the tenth root, the formula would be' 
 transposed into : 
 
 y 
 
 0.30 + 0.30 
 
 VV&PV (mi ma ms m* m, me) (m/ m/ m/ m/ m./ m/) 
 
 If one eye be entirely lost, the disorder of the visual act would 
 be represented, in vocations with higher visual demands, the fifth 
 root, and in such with less demands the seventh root. The same 
 calculation may be done for serious disorders which have the same 
 relations as the loss of one eye.
 
 THE FORMULA OF MAGNUS. 51 
 
 CHAPTER Vm. 
 
 THE METHOD OF CALCULATION WITH THE FORMULA 
 OF MAGNUS. 
 
 §16. What Does this Formula Mean? 
 
 In Our Formula for the Ocular Earning Ability, E=F/K 
 
 X 
 
 the visual act being F and V'K the ability to compete, by resolving the 
 act of vision F into its physiologic factors necessary' for the earning 
 ability, C is the maximal central visual acuity, P the visual field and 
 M the muscular action (Chap. VI., § 11-14), we had acquired the 
 
 expression: F=C (max.) V P 1^ M for the physiologic act wliile 
 
 X 
 
 for the ability to compete v'^we had (Chap. VL, § 11-14) : 
 
 VY=f^^^'^^V'¥VlL 
 
 The complete formula for the ocular earning ability being the 
 following : 
 
 E = C („,ax.) V P V M f ^' '^^' V P V' M. 
 
 At the first glance it might seem that our formula has too much 
 of the mathematical stamp and that its handling does not seem 
 easy nor convenient, and it has been called "too complicated" 
 (Groenouw 12). But this reproach only shows that those making 
 it did not comprehend or understand its meaning. This formula 
 is the numerical expression for the normal visual earning ability, 
 and while this is a composite quantity its mathematical expression 
 must, of course, be composite. This is especially true, for each of 
 the factors entering into the normal visual earning ability may be 
 impaired and must have an individual influence upon the calcu- 
 lation. If we try to simplify the complicated relations they could 
 only be forced, and an arbitrary speculation substituted for its own 
 composite character. The formulas of Zehender and Groenouw 
 are certainly not real mathematical expressions for the ocular earn- 
 ing ability, but only mathematical results of arbitrary supposi- 
 tions. By the construction of such seemingly simple foi-mulas we 
 depart entirely from the line of conduct nature itself follows and 
 get into devious tracks of arbitrary hypotheses. Our duty is to 
 give expression to the ocular earning ability in a mathematical
 
 52 CONVENIENT FIGURING WITH THE FORMULA. 
 
 manner according to its nature, but in doing this we must not 
 create a formula made easier to handle, but which is nothing but an 
 arbitrary conception. Arithmetical simplicity could only be arrived 
 at by the waiving of the natural relations. While an exact mathe- 
 matical rendering of these may not be so very convenient, we may 
 expect that results may be gained which correspond with the actual 
 conditions. By doing so, such reductio ad ahsurdum cannot be 
 found, as is the case with the simple hypothetic formulas of Zehen- 
 der and Groenouw. The arithmetical results of introducing human 
 beings with three seeing eyes, or nine eyes, or cyclopia, or arriving 
 at the conclusion that one-eyedness is identical with the entire loss 
 of the ocular earning ability, cannot be excused or made acceptable 
 by the arithmetical simplicity of the formula. 
 
 §17. Can Figuring ivith the Fonnula Be Made More Convenientf 
 
 In our last paragraph we had to defend our formula from the 
 reproach of being too complicated, but, under all circumstances, it 
 is the truest mathematical expression of natural conditions and has 
 to be made the starting point for every calculation. We may, how- 
 ever, try to make it more convenient, as it must be admitted that 
 the separate figuring of the individual factors with the root values 
 certainly offers difficulties to the inexperienced mathematician and, 
 therefore, a way has to be found which, while retaining absolutely 
 the formula, materially facilitates and simplifies the calculation. 
 This we do as follows : 
 
 In plate V we delineate each of the factors of our formula in 
 a curve in such a manner that the individual curves give the con- 
 dition of this factor within its working range. For instance, in 
 plate V, line I shows the geometric course of peripheric vis "on. if 
 the scientific value of P as absciss and the economic value V P are 
 taken as ordinates : line II represents the geometric course of the 
 muscular action, if the scientific value of ^I as absciss and the 
 economic or actual value *V M arc taken as ordinates. The three 
 lines. III, TV and Y, show in an analogous manner the ability to 
 compete in its different values, using the oth, 7th or 10th root. By 
 the assistance of these curves we may ascertain, in a given case, the 
 economic value of the impairment of every factor of our formula. 
 We first ascertain the amonnt of impairmeut on the absciss repre- 
 senting the scientific valuation, then we trace vertically the corre- 
 sponding line from this point on the chart, and at the intersecting 
 point where we meet the ordinate on the left of the. curve, is the 
 economic value of the damage. By this method, the very incon- 
 venient handling of the root values and separate figuring of the 
 single factors of the formulae mav he avoided. Thus, with any 
 great amount of mathematical calculation, we may estimate the 
 economic value of each damage of the different factors shown in 
 the tables.
 
 EXAMPLE, VISION IMPAIRED IN ONE EYE. 5S 
 
 In comparing the estimation found in this way, with that re- 
 sulting from actual calculation, we will find a certain difference 
 which might be even in unfavorable cases as much as 1, 5 or 2.0, 
 but which will be generally much less. Such a difference can hard- 
 ly be avoided, because the drawing of the curves and the mathe- 
 matical calculation can not be exactly in congruity ; but as in the 
 fourth part of this book we give a tabular exposition of all values 
 gained arithmetically, we are always" enabled to compare these with 
 those found in the curves. Exact reading of the curves leads to 
 accuracy of the result. By this method, the handling of our for- 
 mula is materially simplified, so that its use offers no difficulty 
 whatever. In order to prove this, we will present some cases to 
 show the reader its convenience. 
 
 §18. Calculation with the Formula. 
 To recapitulate our formula : 
 
 E = c Vv 1/ M j/'^ii:^ WVHi 
 
 C being the maximal central visual acuity. 1^ P the visual field, and 
 
 VM. the action of the extrinsic muscles and \ — — ^ — V P 1^ M 
 
 is the ability to compete'. The latter is composed (Chap. VII., 
 § 15) of the arithmetical proportion of the central visual acuity of 
 
 both ej'es ^-^r — ^ , the peripheric vision /Ip and the muscular ac- 
 
 tion Y^ > with the provision that we make the root exponent higher 
 or loAver, as the case may be, of the value 5, 7 or 10. Let us now 
 figure some examples by the aid of this formula : 
 
 Example I. In a simple case, one eye having suffered a trau- 
 matic diminution of the visual acuity which has a value of V^ or 
 0.5, according to the scientific standard. This injured person fol- 
 lows a trade which has higher visual demands, for instance, is a 
 skilled iron worker. In such a case the maximum C, remains un- 
 changed, becanse this is the higher visual acuity of the sound eye 
 which remains the same. C, is therefore = 1, V P the visual field, 
 
 and }f M the muscular action, remain unchanged. These three 
 factors represent each the value 1. In this case the unknown quan- 
 
 X 
 
 tity is the ability to compete, 1/ ^^ ' ^^ V^/ll 
 
 C -4-C 
 ' ^ " being the arithmetical proportion of the central visual 
 
 acuitv of both eves C, the uninjured eye, remains = 1;C.,. the in-
 
 54 EXAMPLE^ VISION IMPAIRED IX BOTH EYES. 
 
 jiired eye, should be reduced according to our supposition to 0.5 
 of the scientific standard. Looking now on plate I on the absciss 
 for the scientific value 0.5 trace this line upwards until we meet 
 the economic curve (II), and from the point where the line cuts 
 the curve we go to the left and find there on the ordinate the 
 economic value of the scientific estimation for the acuity of vision. 
 As the plate shows, this is about 0.58. By inserting this value in 
 
 the arithmetical proportion of the acuity for both eyes, into '^ * 
 
 we hav? - — ^^— = 0.79. This we insert into the factor 
 
 y ^'"t^Y p"K¥ ; ^'"^ t^^e^ ^^^'6 y 0.79 / P J^M in which V P 
 
 4 X 
 
 and V M are each = 1; the whole value is then V 0.79 X 1 X 1. 
 As this is only a slight injury the ability to compete cannot be 
 impaired very much, consequently we make the root exponent 
 
 10 
 
 X = 10. This value V 0.79 x"! >< 1 we can find in plate V, 
 curve V. We look simply on the absciss for the value 0.79, trace 
 the line from there upwards until we meet curve V, going from 
 there to the left we find on the ordinate the value 0.972. If we 
 insert this value into the formula we would find E = 
 1 X 1 X 1 X 0.972, and as E, in our formula, has always been 
 a fraction of ], it must be multiplied by 100 if it would be repre- 
 sented as a percentage. We have then for E==97.20. If we compare 
 this value 97.20 with the example I (given in the first edition, 
 Magnus, p. 90), which was 97.69, we observe that the difference 
 between the two values is very small. 
 
 Example II. As a second case we will take impairment of the 
 visual acuit}' in both eyes, one having only scientific standard of 
 0.3, the other of 0.4. The injured person may have a vocation de- 
 manding higher visual powers. How would we here figure with 
 our formula ? 
 
 E = c ...ax.v p /M |/Cjf_a^— j.-^ 
 
 The factor C (maximum) i. e., the highest value of binocular 
 visual acuity or what is in this case the same thing, the visual 
 acuity of the better eye. As the scientific value is equal to 0.4, on 
 plate I we look on the absciss for this value, go to the curve and 
 find that it is professionally equal to 0.41. The professional valu- 
 ation of the different' values for the visual acuitv mav also be found 
 on Table B, p. 39.) 
 
 The factor K P remains unchanged == 1. 
 The factor |/^M remains unchanged = 1.
 
 REAL SIMPLICITY OF THE FORMULA. 55 
 
 The factor )/ ^ "^^' x/PX/M which is the ability to compete 
 
 C I C 
 
 will be changed only in the part — r— ^ because the field of vision 
 
 and the ocular muscles are not impaired; both will, therefore, be=l. 
 
 C + C 
 This part ^ — ^ would resolve itself in the following manner as 
 
 the scientific acuity in one eye has diminished to 0.4 and in the 
 
 other to 0.3, as we find out by the curve, the scientific standard 
 
 C 4- C- 
 0.4 corresponds with 0.41 and 0.3 with 0.25; — - — ^ is therefore 
 
 equal to ^^^^^i^— =^=0.33. The entire factor of the ability 
 
 T xKTl^ would be, if we enter the values in 
 
 X 
 
 place of each part: K 0.33X1X1, and the economic equivalent of 
 this value we can find directly on plate V. We have only to decide 
 if the eyes have been disfigured from leucomata of the cornea re- 
 sulting from the injury and if from the aesthetic standpoint the 
 ability to compete has suffered. If this be the case, we take for 
 the root exponent 5 and look on plate V on the absciss for 0.33; 
 from there we trace upwards till we meet curve III and read to 
 the left on the ordinate the economic value 0.806. The ability to 
 compete would, therefore, be equal to 0.806. If we now enter all 
 the values we found into our formula we transpose it as follows : 
 
 E=c„.ax.xi/p xVm X\^-^X\/ ? XVM. 
 
 E = 0,41 X 1 X 1 X 0.806 = 0.33046 which in the form 
 of a percentage equals 33.064 per cent. But, if we should take in 
 the foregoing example a slighter impairment of the ability to com- 
 pete and figure it, not with the exponent 5 but with the exponent 
 10, we would receive the result E =37.331 per cent. The earning 
 ability in this case would be 4.285 per cent greater. These ex- 
 amples should be sufficient to explain our methods. 
 
 We now see that calculating with our formula is really simple. 
 All we need is to insert the values of the individual factors into the 
 formula as we find them on the plates. When this simple pro- 
 cedure is done, the formula has been reduced to an easy multipli- 
 cation example. As we have said before, by reading the curves 
 the values found are often a little different from those by full calcu- 
 lation; but as this difference is not great and may be avoided to a 
 great extent by a careful reading, this fact deserves but little con-
 
 56 SIMPLICITY OF THE FORMULA. 
 
 sideration. Besides this, the values found by reading the diagrams 
 may at any time be regulated by comparing them with the tabulated 
 values compiled in part IV. 
 
 We believe that by construction of the curves, the calculation 
 has been so simplified that in spite of the seemingly complicated 
 composition of our formula, it can be done by even an inexperienced 
 mathematician. Reservation must be made in cases where the in- 
 jured person had possessed before the time of the accident only one 
 eye or was weak sighted. In such cases special modifications of 
 the calculation have to be made which will be explained in the fol- 
 lowing chapters.
 
 PART SECOND. 
 
 Special Consideration of Various Ocular Injuries 
 and Visual Defects,
 
 58 INJURIES OF THE VISUAL FIELD. 
 
 CHAPTER IX. 
 
 §19. The Relative Importance of Disturbances of the Visual Field. 
 
 In estimating defects of the visual field we should remember 
 that two-thirds of the binocular field belongs to and is controlled 
 by both eyes (yellow area of Fig.l, plate IV.) Under certain cir- 
 cumstances these disorders have only monocular effects. For in- 
 stance, in the case of nasal hemianopsia (Schroeter 38, p. 19 and 
 our Plate IV, Fig. 3.) Such limited disorders are not considered 
 detrimental to the earning ability because the field of vision does 
 not suffer restriction of its normal limits. 
 
 An experienced calculator may easily ascertain the arithmetical 
 values of the different defects of the visual field, but for complete- 
 ness' sake we here develop these values for a series of disorders 
 which may be inserted into the formula for the earning ability. 
 The following explanations are considered only for the binocular 
 field of vision : 
 
 1. Concentric peripheric contraction of slight extent with nor- 
 mal central visual acuity not extending to 70° (Chap. 7, § 13) is 
 of no importance in this relation and thus may be omitted. If it 
 exceeds 70° but does not go beyond 60°, the field of vision P is to 
 be inserted as two-thirds, into the formula for the earning ability. 
 The earning ability is then 80.012* ; its impairment being 19.998. 
 
 2. Concentric peripheric contraction of a greater extent with 
 normal central visual acuity inaterially exceeding 60°, reaching 30° 
 causes two-thirds loss of the binocular field, the remainder of which 
 should be considered as one-third in the formula for the earning 
 ability; consequently the earning ability drops to 54.65 (55 per 
 cent.) ; the impairment being 45.35 (45 per cent.) The same esti- 
 mation is given for any limitations between 30° and 60°. 
 
 3. Concentric peripheric contraction of the highest degree with 
 remaining normal central visual acuity always means, according to 
 our supposition, an entire inability to earn (Ch.V, § 11). Schroeter 
 (37, p. 21) takes for granted that in such cases an earning ability 
 of 25 per cent, may still exist and that the impairment would only 
 be 75 per cent., but according to our practical experience, we can- 
 not share this view with Schroeter. A man who has only central 
 vision left is, under all circumstances, entirely unable to work and 
 should be allowed 100 per cent, indemnity for the loss of his earning 
 ability. Practically such cases are -not frequent, at least not as 
 
 •For simplicity's sake the calculation may be made with the whole numbers 80 percent. 
 and 20 per cent.
 
 COXTKACTIOX AXD HEMIANOPSIA. 59 
 
 accidental injuries. The double-sided hemianopsias which are like- 
 wise very infrequent (Magnus 24) and of which there has only 
 been reported one traumatic case (Schmidt-Eimpler 35, p. 181) 
 are considered in the same category. 
 
 4. Concentric peripheric contraction of the field of vision in 
 one eye causes diminishment of the entire field of one-sixth, as only 
 the exterior portion (the red or blue area in Fig. 2) is monocular. 
 The sound eye will equalize the disorder of the common portion of 
 the field of vision caused in one-sided concentric contraction. Even 
 very serious concentric contractions limited to one eye will impair 
 the total value of the field of vision to but one-sixth; the earning 
 ability in such cases is 90.45& (90 per cent.) ; the imiDairment 
 9.542 (10 per cent.) 
 
 5. Homonymous hemianopsia dextra vel sinistra causes loss 
 of 11/2 the binocular field of vision, the earning ability becom- 
 ing, according to our estimation, 68.302 (70 per cent.) ; the im- 
 pairment 31.698 (30 per cent.) We make no difference between 
 right or left-sided hemianopsia, but for the purpose of indemnifica- 
 tion give them the same value. Schroeter (37, p. 17-18) proposes 
 to allow 45 per cent, for right-sided hemianopsia and 30 per cent, 
 for left-sided, because, according to his idea, the right half of the 
 field of vision is professionally of more importance than the left one. 
 While it must be admitted that the loss of the right half of the field 
 of vision is especially embarrassing in the beginning for certain 
 occupations, for instance, reading and writing, and is more in- 
 convenient than in case of the corresponding loss of the left half, 
 we would not indemnify hemianopsia on the right side higher than 
 the left, for it is always a question whether or not the above diffi- 
 culties are more of a psychical character (Knies 16, p. 28) than 
 due to the actual loss of vision ; then again those men who are gen- 
 erally exposed to accidental injuries do but little reading or writing 
 in their business; and then the person ultimately becomes accus- 
 tomed to using the left sides of the visual fields. Besides this 
 there are many occiipations in which the loss of the left field would 
 be as bad as that of the right and for left-handed persons the loss 
 of the left side would certainly be inore inconvenient than that of 
 the right. We, therefore, do not advise a higher valuation of the 
 right field of vision. 
 
 6. In the case of vertical homonymous hemianopsia the loss 
 is equivalent to that of the horizontal forms: Schroeter (37, p. 20) 
 complicates the matter again in that he makes a difference in the 
 valuation of the upper and the loAver half of the field. 
 
 7. The loss of both the temporal halves of the field of vision 
 leaves two-thirds of the binocular field, but this is not any more 
 a common field : the left half belongs to the right eye and the right 
 half to the left (Plate IV, Fig. 2) : but this condition does not seem 
 to produce special disorders in actual practice. We enter the value 
 of this field of vision as two-thirds P in the formula for the earn-
 
 60 he:miaxopsia and partial defects. 
 
 ing ability which results in the value 80.012 (80 per cent.) ; and for 
 its impairment 19.988 (20 per cent.) Schroeter (37, p. 19) gives 
 this value as 20 per cent., making our figures about the same. 
 
 8. By the absence of both nasal halves the common field suffers 
 much restriction, as there are no more peripheral portions common 
 to both eyes. The two temporal halves of the field of vision left, 
 touch each other at the point of fixation (Plate IV, Fig. 3), the 
 right half of the field (blue in Fig. 3) belongs only to the right eye, 
 the left half (red in Fig. 3) only to the left. Because the field of 
 vision has not suffered a restriction and there is no acuity from this 
 condition, the earning ability is not curtailed. 
 
 9. Absence of the nasal half of the field of vision in one eye 
 does not cause diminution of the entire field because both the nasal 
 halves are in the common binocular field (yellow area, Plate IV, 
 Fig. 1.) If one nasal half be lost, for instance, that of the left 
 eye, it only causes a change in the form of the binocular field. The 
 right half of the heretofore common field would now be monocular, 
 belonging only to the right eye; the left half of the entire field 
 would have the peripheric portion belonging to the left and a cen- 
 tral one common to both eyes while the right half to the full extent 
 of the field of vision belongs only to the right eye (Plate IV. Fig. 
 4). An impairment of the ability to earn could not be deduced 
 from this condition because the extent of the total field of vision 
 has not suffered restriction. Cases occurring under the headings- 
 of 8 and 9 could be used to prove that accidental injuries do not 
 always cause impairment of the earning ability or allow of claims 
 for indemnification. This is noted in the German Accident Insur- 
 ance Law, Chap. I., § 3. 
 
 10. Loss of the temporal half of the field of vision of one eye 
 from the point of fixation to the outer part, for instance, of the 
 light eye (Plate IV, Fig. 5) affects only the range of the total 
 field of vision supplied by the right eye (blue area. Fig. 1) Ac- 
 cording to our classification, the binocular or total field would be 
 diminished by one-half of the exterior concentric zone (Fig. 1) 
 which would he one-sixth of the total field. The field of vision left 
 would represent five-sixths of the original amount, but the right 
 balf of the common field would now be only a monocular one be- 
 longing only to the left eye ; the left half of the common field would 
 be unchanged, the field would then take the form of Fig. 5, Plate 
 IV. According to our calculation the ability to earn would be 
 90.458 (90 per cent.) ; the impairment thereof 9.542 (10 per cent.) 
 Sehroeter's estimation (38, p. 21) for the latter is 10.8. 
 
 11. Partial defects in the field of vision in only one eye are 
 very seldom injurious to the working ability, if they affect only the 
 common range of the total field (yellow area, Plate IV, Fig. 1), 
 because the portion lost in the one field is compensated for by that 
 of the other. But, if the particular defect reaches into the mo- 
 nocular part of the total field (into the red or yellow part of Fig 1),
 
 TABLE OF VISUAL FIELD DEFECTS. 
 
 61 
 
 a diminution and -u-itli it a disorder of the field of vision could be 
 shown. In such cases "vre suggest an estimation according to the 
 quota for the loss, for instance, if it comprises one-half the monocu- 
 lar part of the field, the earning ability would then be 90.458 (90 
 per cent.) ; the impairment thereof 9.542 (10 per cent.) 
 
 12. Partial defects of the binocular field should be valued ac- 
 cording to their extent. The physician may settle how much is left 
 after deducting the defect from the binocular field. 
 
 13. Total loss of the field of vision of one eye causes diminish- 
 ment of the binocular field by only its peripheric part, one-sixth 
 (the red and blue parts, Plate IV, Fig. 1.) 
 
 We condense these different results in a tabular form : 
 
 THE EARNING ABILITY AND THE IMPAIRMENT THEREOF IN 
 
 THE DIFFERENT DISORDERS OF THE FIELD OF VISION 
 
 WITH REMAINING NORMAL CENTRAL 
 
 VISUAL ACUITY. 
 
 VARIETY OF DEFECT. 
 
 ; _ 2 ^^.2 ; Percentage. 
 
 o o a «« 
 •- o 
 
 "I % g-ojEarning Impair- 
 'h'3 S'®; Ability, meut. 
 
 f Partial defects in the field of one eye ") 
 I Concentric contraction of the field of | 
 1. { one eye )■ 
 
 1 Absence of the temporal half | 
 
 1^ Absence of the entire field of one eye } 
 { Concentric contraction of both fields ^ 
 
 rt I reaching to 60° 
 
 ' 1 Absence of the temporal half of both \ 
 
 I fields _ J 
 
 o I Homonymous hemianopsia dextra \ 
 
 ' \ vel sinistra superior vel inferior J 
 . (Serious concentric contraction of 
 
 ■ \ both fields reaching to 30° 
 
 c I Total concentric contraction of both ) 
 ( fields reaching to 5° j 
 
 { Absence of the nasal halves of both \ 
 
 g I fields 1^ 
 
 ■ I Absence of the nasal half of one ( 
 L field j 
 
 ^ 90,458 9,542 
 
 % 
 
 80,012 
 
 19,988 
 
 V2 
 
 68,302 
 
 31,698 
 
 1/3 
 
 54,650 
 
 45,350 
 
 \ ^ 
 
 0,000 
 
 100,0 
 
 1 
 
 100,00 
 
 0,00 
 
 The foregoing figures are made for both higher and lower 
 visual demands where the central visual acuity remains normal. 
 In cases of serious injury to the field of vision where the ability to
 
 62 COMPLICATED riELD DEFECTS. 
 
 compete suffers it is necessary to figure for the higher demands 
 where the oth or 7th roots may be used. This is done in table 
 Ylla, in the IVth part of this book. 
 
 ^20. Disorders of the Visual Fields Complicated hy Injury to the 
 Central Visual Acuity of Different Degrees in Either Eye. 
 
 As in practice the peripheric "^dsion as well as the central acuity 
 in one or both eyes may be found injured, it is necessary to explain 
 such relations. In the following table the different disorders of the 
 field of vision and the value of the remainders are given in the two 
 left columns, while in the right column we find figures which serve 
 for estimation of the earning ability, in all cases where there are 
 disorders of the field of vision in connection Avith damage to the 
 central acuity, differing in either eye. We first settle what is the 
 arithmetical value of the remaining field of vision, for instance, it 
 might be five-sixths ; then we find the value that the earning ability 
 would have if the otherwise complicated disorder of the visual 
 acuity alone existed. We then read from tables Y or VII of the 
 fourth part without an}' trouble; if, for instance, one eye has a 
 Aisual acuit}' of 0.55 and the other 0.25, according to table V, the 
 earning ability would be 61.078; if the injured person follows a pro- 
 fession demanding high vision. Xow we multiply this value G 1.078 
 with the number in the table on page 63 next to the field of 
 vision; as in our example the arithmetical value of the field of 
 vision Avould be five-sixths we would then have to multiply 61.078 
 with 0.90-158; this would give us an earning ability of 55.250. 
 
 Let us take another example; in concentric contraction of the 
 field of vision reaching to 30° in both eyes the arithmetical value 
 of the remaining field would be one-third; if one eye has central 
 acuity of 0.40, the other of 0.20 and the demands in the profession 
 of this pai-ticular individual are high, both the central acuities of 
 the vision would have an earning ability of 36.273 ; this value we 
 would multiply with the number we find in the table next to the 
 corresponding value of the field of vision, i. e., next to one-third 
 — 0.5465, from wdiich the earning ability would result in 19.823 
 and its impairment 80.177. 
 
 If one eye be entirely lost while the other suffers impairment 
 of its central acuity, the numerals given in the table on page 63 
 do not hold good, we would have to use those on page 64; the calcu- 
 lation is the same. We first ascertain (if for instance one eye be 
 totally blind and the other has only a visual acuity of 0.4 and a 
 field of vision of two-thirds, provided we have a profession with 
 higher visual demands), the degree that the earning ability would 
 have if the field of vision would not have taken part and if the 
 acuity of vision of l>oth eyes had suffered to the above extent, which, 
 according to table V, part IV, would be 24.166; this value we mul- 
 tiplv with 0.57708 and get 13.946 as an expression for the degree 
 of the earning abilitv. If the profession demands less vision we 
 would multiply by 0.59238.
 
 TABLE FOR COMPLICATED FIELD DEFECTS. 
 
 63 
 
 AUXILIARY DATA FOR THE ESTIMATION OF THE EARNING 
 
 ABILITY IN DISORDERS OF THE FIELD OF VISION 
 
 WHERE THE CENTRAL ACUITY OF BOTH 
 
 EYES IS IMPAIRED DIFFERENTLY. 
 
 Variety of Defect. 
 
 <D 
 
 
 r3 O 
 
 
 >2 
 
 
 o 
 
 
 
 
 
 
 o <v 
 
 o 
 
 •-r!^ 
 
 o +=• 
 
 Ul 
 
 U O 
 
 > 
 
 P=R 
 
 
 1.. 
 
 ['Partial defects in one field. 
 
 Concentric contraction (higher 
 and lower degrees) in only 
 one field. 
 
 4. 
 5. 
 
 y\ % 
 
 Absence of the temporal half | 
 of one field. j 
 
 Small concentric contraction") 
 ofboth fields to 60°. | 
 
 Absence of the temporal half | 
 ofboth fields. J 
 
 Homonymous hemianopsia 
 dextra vel sinistra superior 
 vel inferior. 
 
 Great concentric limitation of 
 both fields reaching to 30°. 
 
 Total concentric limitation of 
 both fields reaching to 5°. 
 
 'A 
 
 0.00 
 
 Percentage. 
 
 0.90458 
 
 0.80012 
 
 0.68302 
 
 0.000 
 
 f Absence of the nasal halves of ^ 
 
 I both fields. | 
 
 I I 
 
 I Absence of the nasal half of \ 
 y one field. j 
 
 Aa these disorders of 
 the field of vision do 
 not condition an im- 
 I pairmentof theearning 
 ability, only the disor- 
 der of the acuity of 
 vision would have to 
 be indemnified.
 
 64 TABLE FOR LOSS OF ONE EYE AND VISUAL FIELD. 
 
 AUXILIARY DATA FOR THE ESTIMATION OF THE EARNING 
 
 ABILITY IN LOSS OF ONE EYE COMPLICATED WITH 
 
 INJURY TO THE VISUAL ACUITY AND 
 
 VISUAL FIELD OF THE OTHER. 
 
 These four numerals are given by the following operation; whether 
 the peripheric vision P is limited or not, we always have for the 
 earning ability : 
 
 E 
 
 = c VTili]/^^yThi==cyFhK^^^~^ 
 
 ==cvMy 
 
 p _|_ p i 20 
 
 ^^^^ Vm vt V^ 
 
 10 
 
 The quantity C V M [/ ^^- Vll , in which the 
 
 muscular action M has to be regarded as abnormal, for a case in 
 which one eye is lost, is taken directly from table V. or table VI. ; 
 to find E it must, therefore, be multiplied as follows : 
 
 20 
 
 p = 5^ multiplied with f^ V % = 0.90458. 
 
 20 
 
 p = 2/3 - " YJ4 VVs = 0.80012. 
 
 20 
 
 P=>< " " 1^ 3^ V'l^ = 0.68302. 
 
 P = >^ " " V34 v"r = 0.54650. 
 
 Where we have to figure the earning ability in the case of the 
 loss of one eye, we have to multiply thus : 
 
 For Group I. I For Group II. 
 
 10 H 
 
 P=3^withl/ 3^ J^ 3^ =0.73602 P=5^with|A3^ K 5^ =0.74685 
 
 10 14 
 
 P=8^5 " /K5KM5=0.65580 P=X5 " /Ms 1^5=0.69832 
 
 10 14 
 
 P=^ " /% V' ^ =0.57708 P=^ " V" 2^ 1^=0.59238 
 Eegarding these fractions see Chap. XI., § 23.
 
 PECULIAE KELATION OF OCULAR MUSCLES. 65 
 
 CHAPTER X. 
 
 THE IMPAIRMENT OF THE EARNING ABILITY FROM INJURIES 
 TO THE EXTRA-OCULAR MUSCLES. 
 
 §21. General Bemarhs Regarding the Importance of Injuries to 
 the Extra-Ocular Muscles. 
 
 The ocular muscles have a peculiar position, for the binocular 
 act can only exist so long as all the extrinsic muscles of both eyes 
 are functionally undisturbed ; as soon as one becomes paralytic, with 
 the beginning of diplopia, monocular vision ends and for profes- 
 sional purposes only one eye is at the patient's disposal. For the 
 person with two normal eyes, a paralysis of one muscle is practi- 
 cally identical, for professional purposes, to the loss of the eye and 
 must be so considered in determining an impairment of the earn- 
 ing ability. If the injured person have only one eye, the condi- 
 tions are quite different ; for such a case a paralysis of one external 
 muscle means a perceptible, but in a visual sense, a relatively insig- 
 nificant impairment. For such a case the professional act of vision 
 is not annulled, but is more or less disturbed. For exhibiting this 
 peculiar relation of the ocular muscles, we considered in the for- 
 mula for the professional binocular act of vision, the extrinsic ocu- 
 lar muscles as the factors of a product, to meet this demand ; with 
 the paralysis of only one muscle the binocular professional act en- 
 tirely disappears and is changed into the monocular form because 
 the product becomes if only one factor becomes 0. In the for- 
 mula for the monocular act of vision we express the arithmetical 
 value of the extrinsic ocular muscles as the sum of 6 numerals, cor- 
 responding with the number of the ocular muscles. If one of these 
 be lost, the sum only loses this numeral. In the monocular act 
 of vision, as well as in the binocular, we introduced the numerical 
 expression for the extrinsic ocular muscles as the 4th root, to be 
 able to give expression to the different values of the ocular and 
 muscular functions (Chap. VI., § 11). The other visual functions 
 have a different value than the muscular movements, which may 
 be considered only auxiliary functions of the visual act; profes- 
 sionally and arithmetically this fact cannot be neglected and so the 
 ocular muscles have a root value in our formula. The formula for 
 the binocular and monocular professional acts of vision have been 
 made as follows (Chap. VI., § 14) : 
 
 Binocular Vision 
 
 ^^S2=C f^ P I' (mim2m3m4m5m6) (m/m2'm3''m/m5'm60 
 
 Monocular Vision 
 
 =Si=Cy ^ P y 3^mi + mo + m3 + mi + m5 + m6
 
 66 UXCOMPLICATED PARALYSIS OF OCULAR MUSCLES. 
 
 §22. The Estimation in Paralysis of Muscles Uncomplicated hy 
 Other Visual Disorders. 
 
 Ill the foregoing paragraph vre again developed the formiUas 
 for binociilar and monocular vision. We will now try to figure 
 the extent of the earning ability in disorders of the extrinsic mus- 
 cles of originally normal eyes. As shown already, the earning 
 abilit}' is composed of the two factors of the act of vision and the 
 ability to compete; the formula of the visual act is shown in the 
 foregoing. In order to figure the value of the earning ability we 
 will now have to state the formula for the aljility to compete, which 
 is the xth root of the visual act (Chap. IT., § 9; Chap. YIL, 
 § 15) ; in every ocular injury considered aside from the central 
 acuity, the latter has the greatest influence upon the visual act 
 and is placed with the arithmetical proportion of its two values into 
 the formula for the ability to compete. If the injury be slight we 
 choose the root exponent 10; when serious the exponent 5 or 7. In 
 the case of the loss of one eye, we proposed to take 5 or 7 as the 
 root exponent. As the binocular process is annulled for economic 
 purposes, the individual has to be regarded as blind in one eye; 
 but in fact there is really a difference between an actual one-eyed 
 person and one who has to suddenly rely upon the monocular act 
 of vision on account of paralysis of the muscles, because there is 
 not only a chance of having the paralysis cured but later there 
 may be some use of the eye which has been excluded from the 
 binocular act for peripheral vision, as soon as the patient has 
 learned to suppress double images. In cases of paralysis of the ex- 
 trinsic ocular muscles we would insert into the calculation the 
 ability to compete with the root exponent of 10 which we have 
 chosen for ocular injuries of a slight or moderate degree. The 
 formula for the ability to compete in the monocular act woiild 
 thus be : 
 
 y^'^'^i^j 
 
 -A. (mi + m-; + ms + m4 + ms + me) 
 
 and the formula for the earning ability in the monocular act 
 would be: 
 
 Vj^pf 
 
 E=lcr^Pr^im + m + ....) 
 
 l/lC + 0-,A V 
 
 "Yz (m: + mz + TCiz + mi + ms + me) 
 
 After having developed in the foregoing formula the expression 
 for the earning ability for a one-eyed person, we may figure by
 
 PAIJALYSIS OF l^ECTUS EXTERXUS. 67 
 
 concrete examples the impairment of the earning ability in case 
 of disorders of the mnscles. 
 
 Supposing somebody suffers by an accident a paralysis of the 
 rectus externns of one eye; the binocular act of vision would be 
 immediately excluded, because if the individual wishes to work 
 at all he must cover the eye and therefore exclude it from the act 
 of vision. The ability to earn which is left should be expressed 
 by the above formula and this may be figured by using the curves 
 in plate lY. ; by inserting the different values the formula would 
 be thus : 
 
 E=l X 0.913 X 0.904 X fO.5 X 0.913 X 0.904=0.8254 X J^O.4127 
 = 0.8254X0.915 = 0.755241, or in percentage E equals 75. 524, 
 the impairment of the earning ability Avould be 24.476 per cent. 
 
 Suppose the external recti become paralyzed, then binocular 
 vision is abolished and here the calculation of the amount of dam- 
 age to the working vision would have to be started from the mo- 
 nocular standard. In figuring the professional loss we woiild con- 
 sider that the value of the muscular action (as stated in the formula 
 for the monocular act as ^ mi + m2 + m.j + m4+m.-,+mfi), would be 
 diminished. Because the muscular action of the one eye used for 
 seeing, if the rectus externus be impaired, would be represented 
 by 5 and not by the full action of 6 ; it would therefore be : 
 
 ys (mi H- m2 + ms + mi + ms) 
 or more simply, two-thirds of five-sixths M. Entering this value 
 into the formula for the monocular act of vision it would be: 
 
 IC 
 
 r=^p7?^"j^Mf-i-^«y^"j/^ 
 
 M. 
 
 Transposing this by the assistance of the curves in plate T., the 
 algebraic formula would be numerically expressed by the following: 
 
 10 10 
 
 E = 1.093 X 0.863 V 0.5 X 0.913 X 0.863 = 0.78792 V 0.39396 
 = 0.7879 X 0.911 = 0.717795 or E = 71.78 per cent. 
 If in a case having the same acuity of vision more muscles bepara- 
 lized in one eye than in the other, this eye should be regarded as 
 excluded from the binocular act and the calculation may be made 
 with the better. If one eye have a lower degree of vision, both hav- 
 ing paralysis of the exterior muscles, that eye which has the better 
 acuity should be regarded as the one which may be used in the pro- 
 fession, though its ocular muscles were more completely damaged. 
 In the following table the earning ability and impairment thereof 
 are given for different cases of paralysis, it l>eing considered therein 
 that the eye used for the profession has a working acuity of at least 
 0.75 for those vocations demanding higher vision and at least 0.50 
 for those with lower demands.
 
 68 
 
 VALUATION OF OCULAR MUSCLE PARALYSIS. 
 
 EARNING ABILITY AND IMPAIRMENT THEREOF IN UNCOM- 
 PLICATED DISORDERS OF THE EXTRINSIC 
 OCULAR MUSCLES. 
 
 VARIETY OF DEFECT. 
 
 t> CO 
 
 2^ « 
 
 < o 
 
 .2^.2 
 o >,£ 
 
 Xi 
 
 03 
 
 be 
 
 a 
 '3 
 
 eg 
 
 or:: 
 * i* 
 
 1—0.75 
 
 Paralysis of the extrinsic muscle of or 
 
 only one eye, 1 1 — 0.50 
 
 Paralysis of the extrinsic muscles of I 
 
 both eyes; of the one eye used 1 — 0.75 
 
 for working only one muscle is or 
 
 paralyzed, ^ 1 — 0.50 
 
 Paralysis of the extrinsic muscles of I 
 
 both eyes; of the one eye used ' 1 — 0.75 
 
 for working two muscles are par- or 
 
 alyzed, X 1—0.50 
 
 Paralysis of the extrinsic muscles of 
 both eyes; of the one eye used 
 for working three muscles are 
 paralyzed, 
 
 75.496 
 
 1—0.75 I 
 
 OR 
 
 1—0.50 62.395 
 
 Paralysis of the extrinsic muscles | 
 of both eyes; of the one eye used 
 for working four muscles are par- 
 alyzed, I 2^ 
 
 Paralysis of the extrinsic muscles 
 of both eyes; of the one eye used 
 for working five muscles are par- 
 alyzed, I }4 
 
 Paralysis of all extrinsic muscles of 
 the eye used for working, i 
 
 1—0.75 
 
 OR 
 
 1—0.50 
 
 1—0.75 
 
 OR 
 
 1—0.50 
 1-0.75 
 
 OR 
 
 1—0.50 
 
 24.504 
 
 71.805 ' 28.195 
 
 67.530 32.470 
 
 37.605 
 
 55.811 ! 44.189 
 
 46.125 I 53.875 
 
 0.00 1100.00
 
 EPICKITIC KEMAEKS. 69 
 
 §23. Epicritic Remarhs Concerning the Foregoing Results. 
 
 It may perhaps at first sight be deemed remarkable that we 
 find such a great difference between the earning ability in the case 
 where 5 extrinsic muscles are paralyzed and the valuation of com- 
 plete paralysis, for we have put down for the first instance an im- 
 pairment of 53.875 while we state the latter as 100 per cent. The 
 latter figure is certainly correct, for it is impossible for an artisan, 
 even though he have normal acuity of vision, who suffers paralysis 
 of all the extrinsic muscles which move the eyeball to be able to 
 earn. The consensus of authorities gives the same opinion (Chap. 
 VI., § 11). In specific cases, where only one muscle remains func- 
 tionable, for instance, the rectus superior, a greater impairment 
 of the working capacity might be found, for this muscle has but 
 little influence upon the average vocation. If the rectus intemus 
 remains, the working capacity would be greater, for this is used 
 much more often. Therefore, we might give each of the extrinsic 
 muscles a different valuation (Chap. YL, § 13) in considering 
 the specific demands of the vocations in which the injured person 
 has previously labored, or we may get around this point by giving 
 a higher valuation in such cases to the ability to compete ; thus 
 figuring not with the 10th but with a 5th or 6th root (table Xllla, 
 part IV). 
 
 By such a method we are enabled to simplify our mathematical 
 calculations in specific cases, even though we treat all the ocular 
 muscles equally. Thus by choosing the root exponents arbitrarily, 
 the physician is allowed to express the individuality of each 
 case. General calculations applicable for the individual values of 
 each muscle cannot be given without doing violence to the pecu- 
 liarity of the particular profession. Thus we hold it for the best 
 to give each of the extrinsic muscles the same valuation, that is, 
 one-sixth of the total value. "We regard these figures as generally 
 applicable as the lowest standard of the earning ability or the im- 
 pairment thereof, leaving it to the calculator to change them event- 
 ually according to specific demands of the particular case. That 
 paralysis of the levator palpebrae superior might suspend the use 
 of the affected eye is self-evident and such a case should be con- 
 sidered professionally as one of monocular vision.
 
 70 ACTION IX moxoculaeis:m. 
 
 CHAPTER XL 
 
 §24. What Action is Necessary if the Injured Person Has Previ- 
 ously Only Had the Use of One Eye ? 
 
 The scientific and economic conception of monocnlarism is not 
 the same. "While, from a scientific standpoint, a person is to be re- 
 garded as one-eA'cd whose eyeball has been removed or who is other- 
 wise hopelessly blind, the meaning of one-eyedness (monocnlarism) 
 developed for professional life, has a much wider range. For eco- 
 nomic purposes a man must be regarded as possessing only mo- 
 nocular vision who has but the one useful for the earning of his 
 living, if the other has insufficient vision for this purpose. Tlie 
 condition of the poor eye and the degree of its visual acuity is 
 immaterial in this consideration. If it is not a useful eye, that 
 person may be considered to have but monocular vision for the 
 purpose of earning his living, for he could not follow his trade if 
 he lost the more normal eye, and would be in the same position as a 
 man who had originally one blind eye or non^ at all. Although 
 there is an optical and scientific difference, the economic conse- 
 quence would be the same ; both would be unable to work, although 
 the weak and professionally insufficient eye in the one case, not 
 being entirely blind, is of inestimable value to him ; but this would 
 have nothing to do in judging his ability to earn ; he would be pro- 
 fessionalh' incompetent if the uninjured eye is unequal to the de- 
 mands of the trade. Therefore, for our purpose, we would regard 
 many individuals as possessing but monocular vision who, ac- 
 cording to the scientific standard, can see more or less with both eyes. 
 Those who squint and suppress the image of one eye, those who 
 have sufficient refractive error, which cannot be corrected or which 
 lowers the acuity of vision to 0.15 or 0.05 (according to the visual 
 recpiirements of the trade), those who have congenital monocular 
 amblyopia, etc., belong to this class. 
 
 In the case of an individual whose previous condition would 
 be professionally regarded as that of monocnlarism, who suffers 
 an injury to his more normal eye, how would we estimate the earn- 
 ing ability? In the calculation of such a case the previous con- 
 dition has to be considered and there is here a material greater 
 impairment to the earning power than in the case of a person 
 with two normal eyes. In the case of an ocular accident hap- 
 pening to a workman, we must not only consider his own peculiar 
 ocular conditions but the side of the insurance company, employer 
 or defendant from whom he may be seeking indemnification for his 
 injury, so that we must be sure that the second parties are not bur- 
 dened with the blame for an impairment which the laborer had be- 
 fore the accident. "We solve this difficult problem with a just and
 
 ABILITY TO COMPETE IX MONOCULARISM. 71 
 
 fair consideration of tlie claims of botli parties, when we start with 
 the supposition that with those workmen who originally possess 
 only the working use of one eye, the condition should be regarded 
 as normal, and therefore, for them the monocular act of vision is 
 the normal one and equal in value to the binocular act of the person 
 with two normal eyes. Thus out of fairness to the employer and 
 the Insurance Company and the workman himself, we would not 
 arithmeticall}' consider the scientific standard of binocular vision 
 in the case of a workman who has entered into his employment 
 with only one working eye and who has suffered an injury to it. 
 We calculate his claims in the same manner in which we figure 
 the ability to compete (Chap. IV., § 9; Chap. VII., § 15), wliich 
 is equal to the visual act and acuities of vision of both eyes in an 
 arithmetical proportion thus: 
 
 y 
 
 ^' + ^' VTVm. 
 
 2 
 
 As in estimating the ability to compete of a person possessing 
 monocular vision who has suffered injury to it through an accident, 
 we put the visual acuity of one eye with its 'full va'lue C under the 
 
 V ; thus the formula for the ability to compete of the one-eyed 
 person would be : 
 
 r 
 
 t' •' P VK 
 
 This formula leads to the same results as that which we get for 
 injuries to the visual acuity in binocular vision ; as by this method, 
 a man who has originally one eye would be impaired through an 
 accident to his working eye to the same extent that occurs in a 
 binocular case. When an employer hires an individual who is 
 originally in possession of but one eye or who has practically only 
 monocular vision, he does this under the supposition that this de- 
 fect does not hinder him in his Avork and regards this condition 
 as the normal for this particular individual. If this be the case, 
 the ability to compete of such a man may be deemed normal and 
 in estimating his earning ability we would take his ability to com- 
 pete as the 10th root of the normal binocular vision of the man 
 Avith two eyes. But regarding the chances of obtaining work we 
 Avould repeat that there is a difference even in cases of monocular 
 vision; for instance, if a person has in one eye an irregular astig- 
 matism which diminishes the acuity below the working standard 
 so that he cannot use this eye in a profession with higher ocular 
 demands, for economic purposes he would professionally be deemed 
 one-ej^ed, but he would be able to find work much easier than 
 another laborer who has a bad-looking blind eye, for instance cor- 
 neal staphyloma, through blenorrhoea, etc. Therefore, we would 
 make an aritbmotieal difference between such cases, takins: as the
 
 72 EXAMPLE OF INJURY IN MONOCULARISM, 
 
 exponent of the root for the ability to compete the number 10, 
 where there is a good-looking eye and one not entirely blind ; but in 
 the case of a person with a bad-looking blind eye, for the higher 
 ocular demands, we would take the exponent 5, and for lower ones 
 7 ; which are the same values that we took in the case of a workman 
 who had originally two normal eyes. We give the following ex- 
 ample : Supposing the vision of the sound eye in the case of a one- 
 eyed workman be reduced to 0.65 (scientific standard) our for- 
 mula would be the following : 
 
 i 
 
 E = C / P K^nii + m2 + m3 + mi + ms + me) 
 
 ^ GVvr 
 
 (m, + mo + ms + mi + m.^ + m,-,) 
 
 As in this ease the visual field and the ocular muscles are not 
 impaired, and therefore 1, the reduced formula would be : 
 
 E 
 
 = G]riv iM G\' 1}/ 1 
 
 Substituting the professional valuation of the scientific standard 
 for 0.65 from our curves on plate I equals 0.833, and entering it 
 now into the formula which would be: 
 
 E = 0.833 X 1 X 1 K 0.833 X 1 X 1 
 
 the value ]/ 0.833 will be found in the curves of plate Y. ; if for 
 
 instance, we take the root exponent x:=10, then y 0.833 =0.982, 
 which leaves the formula thus : E = 0.833 X 0.982 = 0.818006 
 or E=81.801 per cent. 
 
 In the case of injury to the visual field in an originally one- 
 eyed person we would figure according to the following: the field 
 of vision of a one-eyed person, as we have seen in Chap. VI., plate 
 IV., Fig. 1, is narrower by one-sixth than the field of vision 
 of a normal person. If the right or left eye is gone, either the 
 right or the left temporal segment of the common field of vision 
 blue or red in Fig. 1, plate IV.) would be missing. Thus accord- 
 ing to our arrangement, the monocular field contains 5 parts of the 
 binocular one, which are 3^ of zone I, 3^ of zone II and ~A of 
 zone III. Thus if we desire to make an arithmetical calculation of 
 the limitation to the monocular field of vision, we should start with 
 this five-part arrangement and express the impairments by fifths. 
 The different estimates of damage to visual field would thus have 
 the following values :
 
 VISUAL FIELD IN MONOCULAKISM. 73 
 
 Loss of the temporal half there is retained 3^ 
 
 Loss of the nasal half there is retained j/s 
 
 If the concentric contraction reaches 30° the value 
 remaining is 3^ 
 
 If the limitation on the nasal side is more than 45°, on the 
 temporal side 70°, below 65°, above 40°, the value of the remaining 
 field of vision is ^5.* 
 
 In calculating the amount of damage to' economic vision from 
 injuries to the monocular field, we insert in our formula for the 
 earning ability of the monocular act of vision for the value P the 
 valuation of the remaining field of visison. Our formula being : 
 
 4 
 
 E = C ]/YV (mi + m7+ ms^ m7 + ms + me) 
 
 ] C VYV (mi + mo + m3 + m, + mr, + m,) 
 
 Supposing the remaining portion of the field of vision equals two- 
 fifths, the central visual acuity C and the valuation of the ocular 
 
 4 
 
 muscles V (nn + ms + ms + m* + ms + ms) remain unimpaired, 
 being equal to 1, the reduced formula would be : 
 
 X 
 
 E = 1 lA 2^ ]/ rf 1 vi^ /T 
 
 and as each 1^1, the resultant formula would be : 
 
 X 
 
 ^ = iv yk 1 y 1 r'H 1 
 
 and which can be readily figured, or, if preferable, the valuation 
 can be easily found with the assistance of the curves in plate Y. 
 
 •The value ^is above figured is thus explained : The limitation reaching temporally 
 to 60° from the fixation point leaves -45 of the field of vision, of which a part is lost when 
 the limitation above is over 40°, below over 65° and on the nasal side over 45°, which 
 we estimate as a % loss of the remaining % of the field; therefore, there remains % 
 ofy5 = %5-
 
 74 MEANING OF ECONOMIC WEAK VISION. 
 
 CHAPTER Xn. 
 
 ESTIMATION OF ACCIDENTAL INJURIES IN THOSE CASES IN 
 
 WHICH ONE OR BOTH EYES DID NOT POSSESS, BEFORE 
 
 THE ACCIDENT, SUFFICIENT NORMAL 
 
 CENTRAL VISUAL ACUITY. 
 
 §25. The Cleaning of Weah Vision from an Economic Standpoint. 
 
 There are many cases to which trauma occurs in which the 
 eyes had some previous disorder or disease affecting the visual 
 acuity, field of vision or the ocular muscles. It is more especially 
 defective visual acuity that is here considered. A recent article by 
 Walther (47) who reported upon the examination of the eyes of 
 2,672 active workmen (printers, metal workers, wood workers, glass 
 and porcelain workers, woolen workers, electrical and gas workers) 
 fouiul that exclusive of refraction defects that could be corrected 
 by lenses, 611 were more or less amblyopic. Of these 347 (63 per 
 cent.) had congenital defects; 224 (36 per cent.) acquired defects: 
 95 being of doubtful origin. In 15 per cent, the poor sight had 
 been caused by the work. Every practitioner knows how common 
 are opacities of the cornea and other disorders of the ocular media 
 whicli affect the visual acuity in those classes of people that fur- 
 nish laborers and artisans. Considering further how many cases 
 of strabismus, anisometropia, high grades of astigmatism and re- 
 fractional anomalies which are accompanied by weakness of vision 
 of one or both eyes, we will have to admit that many cases of ocular 
 accidents have previously had weak sight and whose acuity of vision 
 did not reach the economic limit, i. e., 0.75 or 0.50. If the physi- 
 cian, who is called to estimate the amount of visual damage, finds 
 inflis]-)utable proof that there was weakness of vision before tbe 
 aeeifleut, what should be his action in fixing the ability to earn? 
 If after an accident to both eyes, he finds only a visual acuity of 
 0.40, he must decide regarding the previous condition of the eyes, 
 for the weakness of vision after the accident may not be solely 
 the result of the trauma, but due in part or whole to causes not 
 connected with it. In such cases particular care must be observed 
 in the arithmetical estimation of the resultant damage to vision ; we 
 are certainly not justified in drawing conclusions from uncertain 
 suppositions about the earning ability before the accident. If we 
 cannot get reliable information concerning the injured person of 
 the results of previous examinations, our estimation would depend 
 entirely upon the impression gained by the present condition of the 
 eve. There are many individuals who combine an astonishing
 
 IMPRACTICABILITY OF GENERAL VISUAL EXAMINATIONS. 75 
 
 amount of working and earning ability with exceptionally low visual 
 acuit}', as has been shown by Groenouw's examples. Therefore, we 
 cannot give each individual, whom we suppose had a weakness of 
 vision before the accident, an earning ability in proportion to 
 the hypothetic degree of this weakness. The possibility or 
 even probability is, that this weak sighted individual pos- 
 sessed a greater ability to earn than might be supposed accord- 
 ing to objective results. Therefore, the physician should only con- 
 sider reliable communications, such as an exact functional examina- 
 tion of the eyes, regarding the previous extent of the weakness of 
 vision in the particular case. If he has no such data, each person 
 suffering from an ocular accident should be regarded as formerly 
 normal; for even if there is a conviction that there was formerly 
 a weakness of vision, justice demands that an arithmetical valu- 
 ation of the former condition could be secured only by a previous 
 functional examination. But this general rule, of course, may be 
 laid aside in those cases in which there are decided opacities of the 
 ocular media, congenital defects, which, through their appearance, 
 have evidently existed for a long time previous to the accident, etc. ; 
 the physician may positively know that such have precluded the 
 possibility of previously existing good working conditions. As this 
 German Accident Insurance law was passed with benevolent inten- 
 tions of protecting the workingman, we divine that his interest 
 should be placed foremost. If we do this, we should stick to the 
 principle that a former weakness of vision should diminish the 
 claims for indemnification of injured workingmen only in such 
 cases where the extent of the weakness of vision before the accident 
 has been fixed by a reliable functional examination. Certainly 
 the Utopian idea of examination of the eyes and other organs of all 
 workingmen before taking employment and at stated intervals 
 thereafter, according to Zehender and others of our colleagues, 
 would fix this matter, but such is impractical except for the rail- 
 road, army and other kindred services. A systematic examination 
 could only be made by a qualified oculist, and it would be impos- 
 sible, as many factories are in small towns that cannot support an 
 oculist. Likewise the financial question renders it impractical, for 
 neither the workingman nor the employer is at present willing to 
 stand the expense, and surely the physician should not be jequired 
 to give his time for nothing, especially considering that he would 
 have to write a certificate and accept responsibility in every single 
 case. Then again, one examination is not sufficient : each one 
 should be re-examined from time to time, as has been done in the 
 railroads. For the latter service, re-examinations are conducted 
 every few years or upon applications for promotion. Such examina- 
 tions are certainly demanded for this class of workmen, for upon 
 their eye-sight and physical condition depends the lives of many 
 others.
 
 76 WEAK VISION" EXISTING BEFORE THE ACCIDENT, 
 
 §26. E.-itiinaiion of Hte EaruiiKj Abililij in Case Weakness of 
 Vision Existed Before the Accident, Which Can Be Nu- 
 merically Fixed Through a Former Functional Exami- 
 nation. \ 
 
 If a workman suffers impairment of his visual acuity by an ac- 
 cident and data exists of his former condition, this weakness should 
 be taken into account in estimating the damages caused by the acci- 
 dent. If in such a case we had based our estimation upon the 
 ocular conditions of the formerly normal-sighted person, the injury 
 would then receive an indemnification which is too high; beiug 
 recompensed for the loss of a something which he never possessed. 
 To prove the correctness of this assertion, let us look at the follow- 
 ing case : 
 
 A w^orkingman coming under Group I who had in one eye for- 
 merly only 0.60 visual acuity, suffers an injury which diminishes 
 this to 0.40,should he be indemnified the same as if he had formerly 
 
 normal visual acuitv? This num has still -*^^>^ of his former 
 
 0,60 
 
 vision, but if his former weakness would not l)o considered, he 
 
 would be indemnified as if his resultant vision was only ^^-^^^ 
 
 Thus allowances for the former visual acuity in cases will have to 
 be made where it is known. Thus, in the estimation of such a case, 
 we W'Ould not enter the quantity 0.40 into the formula, for this 
 would result in too great indemnification, but another X, which 
 bears the same ratio to the unity of the particular group (here 
 higher visual demands, 0.75) as the remaining acuity of vision 
 after the accident (0.40) to the former (0.60) as in the follow- 
 ing proportion : 
 
 X : 0,75 = 0.40 : 0,60 
 
 X = 0.75 X^40 = 0,50 
 0,60 
 As in those cases the use of such an auxiliary C[uantity is neces- 
 sary, we wall introduce for it a special expression : 
 
 Definition: If n is the normal acuity of vision (for working- 
 xnen with higher visual demands n = 0,75 ; for workingmen with 
 lower demands n = 0,50); ni the original acuity of vision of the 
 weak-sighted and Ci the acuity of vision after the accident.* 
 
 We would understand under "modified visual acuity," an acuity 
 Ci' which suffices for the proportion Ci':n =Ci:ni from which we get 
 
 the equation : Ci' = n - . 
 
 ^ ni 
 
 tin forensic praetice the following examples will be seldom found. Considerable space 
 is siven for such eases here to show that our rules are universal and adapted to the most 
 tomplicated as well as the simpler cases. 
 
 *In naine the readinp; tables, the reranininp: visual acuity after an injury would be the 
 scientific standard and would have to be changed into the professional one.
 
 CALCULATION OF CASES OF PREVIOUS WEAK VISIOX. 77 
 
 This expression would be used for the original visual value un- 
 der the following circumstances : if a person begins a trade or 
 vocation with a weaker normal visual acuity than n which we 
 would denominate ni, and then has this eye injured so that ulti- 
 mately there is a visual acuity of Ci, the estimation of his indemni- 
 fication should be based upon the modified visual acuity c/ and 
 not the original acuity Ci- Tf the person be weak-sighted in both 
 eyes, n2 and C2 mark the values for the second eye, corresponding 
 to the quantities iii and Ci ; thus the modified visual acuity c/ must 
 be introduced, as the act of vision is, in this case, dependent upon 
 two modified acuities c/ and c^ . One of these quantities would 
 generally be greater, if both be equal, it is immaterial which we 
 choose; one should be marked Ijy c'max. The formula for the visual 
 act would thus be : 
 
 4 
 S2 = C',„ax. VTVlL 
 
 As at present we only deal with the factor of visual acuity, consid- 
 ering in our examples that the peripheric vision and muscular 
 action are normal, thus estimating their value as 1 in the equation : 
 
 S2 = C'„,ax. X 1 X 1. 
 
 We have now found a value for the visual act S and will have 
 to consider the second factor, the ability to compete K, for the esti- 
 mation of the ocular earning ability E. This quantity K we have 
 identified for our purposes with the act of vision itself but with a 
 difference, whereas we made this factor dependent only upon the 
 miximum of the central acuities of both eyes, we introduced into 
 the other in its stead the arithmetical proportion of the central 
 visual acuities. And as in our case we must regard the modified 
 acuities c/ and c/ as ideally existing, it would seem at first glance 
 
 as if we had to figure with these and to insert for K the value 
 
 gj' _j_ g^' " _ * 
 
 K = g , where we again disregard the (juantities |/ p and ]/ M. 
 
 Such a supposition would be in opposition to statements previously 
 made. Indeed, the ability to compete is a quantity which depends 
 more upon others than upon the individual himself, and while w^e 
 had to say in figuring the visual act : The visual acuities Ci and C2 
 have for the individual the valu'^ c,' and C2' ; we cannot definitely 
 assert a value for this quantity as it is dependent, to a small degree, 
 upon the individual himself. If in the estimation of K we would 
 take as auxiliaries, the modified visual acuities c/ and d' we would 
 express therewith the idea that the acuities of vision Ci and C2 have 
 in other cases these modified values and this supposition is not sup- 
 ported by facts. This simple reflection forces us to accept K in the
 
 78 CALCTLATIOX OF CASLS OF PREVIOUS AVEAK VISIOX. 
 
 form K = -^- — ^ and inserting this and the value of the f(jrmer 
 
 ^ X 
 
 vision into the general formula for the earning ability E = S ^ K 
 the result would be : 
 
 p _ .. 1/ Cl + C2 
 tj C ,„ax. V 
 
 It would seem almost as if a great many tables were desirable for 
 figuring the above formula, because c'max. and -~^ — ^ may have many 
 
 different values and allow of numerous combinations, but it is 
 possible to make use of the above expression for E without going 
 into such detail. "We will use the former expressions and mark 
 for c max. the greater of the two visual acuities Ci and C2 ; then if, 
 for instance, n = 0.75 or 0.50, we estimate from our two main 
 tables Y. or VI., part IV., as an auxiliary quantity an earning 
 ability E which is given in the proportion : 
 
 E = C,„ax.f^+"* 
 
 2 
 
 out of this we get the value of the 10th root 
 
 } 
 
 Cl + C2 E' 
 
 ■< C max. 
 
 and bv insertino; this value into the above formula for E we get 
 
 E — c' l/ ci + C2 
 
 •L' <- max. W ~ 
 
 which reduced to the extremely simple equation, 
 
 Ti C' max. ^ E^ 
 
 C max. 
 
 whose figuring is possible without any difficulty. As we have 
 already shown the quantities c max. and c' max. must be replaced by 
 their professional values. How these can be readily estimated in 
 eases where table II. is not available will be shown by examples. 
 
 Of course, the above formula for E has been deduced under 
 the supposition that the visual field and muscular action remains 
 normal. The same method may be readily used for finding the 
 reduced visual field or reduced value of the ocular muscles. In- 
 deed, the reduced quantities P and M, which were omitted in our last 
 formula for the earning ability E, will form with the same amount 
 part of the auxiliary quantity E' and are taken as such in our
 
 EXAMPLES. 79 
 
 table, which furnishes the visual aciiitics of ci and Cg with re- 
 mainders of P and M, the vakie E'. Therefore, we do not need to 
 estimate the impairments of P and M separately. 
 
 In order to quickly ascertain in all cases of weakness of vision, 
 the corresponding ability of earning, the following has to be done : 
 
 We take the earning ability E' belonging to the really existing 
 visual acuities ci and Ca from one of the corresponding tables, 
 figure the modified acuities of vision c max. and c' max., multiply E' 
 with the greater figure c' max. and divide the product, by the greater 
 of the two values ci and Cg (c max.), but the two quantities c max and 
 c'max. have to be inserted in their professional values; the resulting 
 quotient is the desired earning ability. To show how simple the 
 calculation really is we will exhibit one example each of the differ- 
 ent possibilities which we divide into the following four groups : 
 
 Group I — One eye is normal, the other originally weak-sighted. 
 
 Group II. Both eyes are originally weak-sighted to equal 
 degrees. 
 
 Group III. Both eyes are originally weak-sighted to different 
 degrees. 
 
 Group lY. One eye is blind and the other originally weak- 
 sighted. 
 
 To each of these four groups may be added the accidental in- 
 juries in their different forms. In the following we will explain 
 the single groups with the different accidental possibilities. 
 
 §27. Group I. One Eye is Normal, the Other OriginaUij Weak- 
 Sigh ted. 
 
 In all the example? of thi;^ group we deal with an individual 
 Avhose work requires higher ocular demands (thus n^O.75) and 
 whose eye 1 has at least a visual acuity of ni = 0.75 and whose other 
 has perhaps only ni;=0.60. 
 
 Example 1. *The normal eye remains sound (ci=0.75). the 
 acuity of vision of the other eye 2 is diminished through an in- 
 jurv' to C2= 0.30 the modified visiial acuities are: 
 
 c/=n ''-=0.75^.11=0.75, 
 ni 0.75 
 
 c/=n ''^=0.75 ^•|^= 0.375. 
 n2 0.60 
 
 Table Y. of the fourth part gives the earning ability E belonging to 
 c, = 0.75 and c? = 0.30 as E' =95.41. 
 
 The maximum of the real acuities of vision is Ct = 0.75, of the 
 modified acuities of vision alsoc/= 0.75, and as both values cor- 
 respond according to the table on p. 42 with 1, the desired earning 
 
 ability E will be : E = "" ' '""" ^' - L>< ^M^ =95.41. 
 
 *In these example.'* figures taken from tables in Part IV refer to theTIGermaneditionof 
 Maprniis'book in which the perpentaces are worked over to the thousandths. For practical 
 UKe the American Author only accepts them to tenths and has thns published the tables.
 
 80 EXAMPLES. 
 
 Example "2. If the eye 1 is sound (ci = 0.75) while the acuity 
 of vision of the other eye 2, is reduced to C2=0, the modified acui- 
 ties are : 
 
 c, „^_0.75 „^_ 
 Ci=n = 0. <o „ „^ ^0. it>, 
 ni 0. r5 
 
 c,, = n = 0. / o .^ „ „ = 0. 
 n-i 0.60 
 
 to Ci=:0.T5 and Ci'=U belongs according to table Y., part IV., an 
 earning ability E' = 60.09T. " 
 
 The maximum of the acuities of vision are as above Ci = 0.75 
 and c/ =0.75 to which belongs professionally the figure 1, there- 
 fore, the earning ability is : 
 
 E = ^'"^^' = L><69:CI97 ^ ^^^^^^^ 
 
 C max. J- 
 
 Example 3. If the normal eye 1 suffers such an injury that 
 there only remains a visual acuity of ci =0.50 while the other eye 
 2 remains uninjured (c3 = 0.60) the modified acuities of vision are: 
 
 , Ci 0.30 
 
 Ci = n — = 0.75 ^r-^^ = 0.30, 
 ni U,75 
 
 , c. ^^0.60 
 
 c> =: n = 0. < o ^ ^„ = 0.75. 
 Ho O.dO 
 
 According to table Y., part lY., the acuities of vision Ci =^ 0.50 
 and 02 = 0.60, for the earning ability E' =: T2.02 and because 
 Cmax. = C2=:0.60, c' ,„a.x := C-/ = 0.75 arc figures to be replaced by 
 0.75 and 1, which is (see tal)le) the looked-for earning ability: 
 
 ^ c',n.x. E' 1X72.02 _„_ 
 E= = ,^ ^. = 96.02 (. 
 
 Cmax. 0. / 1) 
 
 Example 4. If the normal eye 1 l^ecomes totally blind (ci = 0) 
 and the other remains uninjured (c> = 0.60) the modified visual 
 acuities are: 
 
 Ci = n =0. (t»„^^=0. 
 Hi O./o 
 
 c. .„.0.60 „„_ 
 Ci = n = 0. / ,. ^., = 0.7o. 
 nj .60 
 
 whose maximum is c-/=O.To. while C2=0. 60 represents the maxi- 
 mum of the real visual acuities. In table Y., part lY., we find as 
 belonging to ci=0 and c-,.= 0.60 an earning ability E':=48.925. 
 so that according to table on p. 42 the figures 1 and 0.7o b?long 
 to 0.75 and O.GO the earning abilitv is: 
 
 J, _ C „„. EJ^lX 48.925 _g. 233 
 
 Cmax. O.^O
 
 EXAMPLES. 81 
 
 Example 5. If both eyes suffer injuries and in 1 there remains 
 only a visual acuity Ci = 0.-t5, on the other 2 only Ca^0.40, the 
 modified acuities are : 
 
 Ci 45 
 
 c, ^^_0.40 „.^^ 
 c/ = n = 0. ( o „ 7.,, = O.oO. 
 n-; 0.60 
 
 Cmax. = Ci= 0.45 and c' max. =^ c/ =0.50 are figures which correspond 
 (see table, p. 4'?). with the values 0.50 and 0.5833 to Ci and C2. 
 According to table V.. jiart IV., there belongs an earning ability 
 E' = 46.284, the final result is: 
 
 ^ c' „,ax. E' 0.583....46.248 ..^ ^_^ 
 
 C max. O.oO 
 
 §28. Group II. Both Eyes are Originallij EqifaUij Weal--Sighted. 
 
 In the following cases we will suppose that the trade has only 
 small ocular requirements (n=U.50) and that the workman origi- 
 nally possessed visual acuity of only ni^nj= 0.40 in both eyes. 
 
 Example 1. If eye 1 be uninjured (ci^0.40) and the other 
 suffers an impairment to about c> = 0.20, the modified visual acui- 
 ties would be according to the following formula: 
 
 , Ci 0.40 
 
 Ci' = n = O.oO ., . „ =0.oO. 
 ni 0.40 
 
 c/= n ^' = 0.50^^=0.25. 
 n,. 0.40 
 
 of which the maximum isc'„,a.x. =Ci' = 0.50, while the real acuities 
 are Cmax. = Ci= 0.40. According to tal)le VI.. part IV.. Cj and c. 
 
 E' = 73.338. 
 and as the \alues according to tal)le. p. 42. correspond to the figures 
 1 and O.TTT • • • . the resulting earning ability is: 
 
 g __ c max. E ^ 1 X 73^38 __ „ . 2Q2 
 
 Cmax. 0.777 .... 
 
 Example 2. If one eye be totally l)lind (c>= 0) while the 
 other be uninjured (ci= 0.40). the modified acuities are as follows: 
 
 c/ = n ^' =0.50^4^=0-50. 
 Hi 0.40 
 
 c/ = n ^' = 0.50^^,^= 0. 
 n< 0.40
 
 82 EXAMPLES. 
 
 as above, Cmax. = Ci= 0.40 and c'max c = 0.50; table VI., part IV., 
 gives as belonging to ciaiid c--, E' = 54.538, and as a Avorking valu- 
 ation we get for the earning ability : 
 
 ^ _ c'„ax. X E _ IX 54.538 „ , ^ 
 
 Cmax. 0.777 . . . 
 
 Example 3. If both eyes suffer the same injury so that there 
 only remains a visual acuity of Ci = C2=0.20 then the modified 
 acuities develop as follows : 
 
 c/ = c./ n ^ - = n ^- = 0.50 ^^ = 0.25. 
 ni Vii 0.40 
 
 in which equation Cmax.= Ci=C2=0.20 and c'max=Ci' = c/= 0.25, to 
 which figures belong the working values of 0.333 . . and 0.4444 . . . 
 For ci and C2 , table VI., part IV., we find an earning ability of 
 E = 29.865, from Avhich we find the real earning ability: 
 
 ^ c^n.ax. E^ 0.444 29.865 _ „„ ^^ 
 
 Cmax. \J.666 . . . 
 
 Example 4. If the injuries in both eyes are different, the re- 
 sulting acuity of ci= 0.20 and of ca = 0.30 we find that the modi- 
 fied acuities of vision Cmax.= c^ =0.30. wdiich are professionally 
 0.555 . . . (p. 42), the calculation for the modified vision would b?: 
 
 c/ = n ''= 0.50 J^-^!^= 0.25. 
 ni 0.40 
 
 / C2 „0.30 c\^n- 
 
 c> = n = 0.50 „ . ,. = 0.3 /o. 
 n2 0.40 
 
 in which the luaximum isc'max. = C2 = 0.375; and as this figure is 
 exactly between 0.40 and 0.35, the middle value of the professional 
 quantities 0.777 . . . and 0.666 . . . , i. e., 0.7222 will correspond. 
 To Ci and C2 belongs E' = 51.228, the earning ability is: 
 
 E = ?:=H_E' ^ 0,722^. . . . 51.228 ^ gg -gg 
 
 Cmax. 0.555 .... 
 
 §29. Group III. Both Ei/cs of ike Individual are Originally 
 Weak-Sighted to a Different Degree. 
 
 In the following cases we deal with workingmen whose profes- 
 sions have liigh visual requirements (n=0.75) but who have origi- 
 nal visual acuity in one eye n i=0.65 and in the other n2 = 0.55.
 
 exa:mples. 83 
 
 c/- 
 
 ■- n 
 
 X 
 
 Ci 
 
 ni 
 
 c/ = 
 
 n 
 
 X 
 
 no 
 
 Example 1. Eye 1 is uninjured (ci = 0.6o) while the visual 
 acuity in the other has been impaired by injury to 0,,=^ 0.20, the 
 modified acuities are: 
 
 ,, ^ ^0.65 „ r-r 
 
 o.< 0x^-^ = 0.75. 
 
 U.bo 
 
 0.75 X^?? = 0.27. 
 0.00 
 
 the maximum c'„iax.= Ci'=0.T5,while we get for the maximiim of the 
 real acuities Cniax.= Ci^ 0.05. The first vahie should be replaced 
 professionally by 1 according to the table on p. 43 ; the second by 
 0.833 ... To Ci andc2, table T., part IV., furnish us the quantity 
 E':^ 77.079, the earning ability is therefore: 
 
 Cmax. 0.8334. , . . 
 
 Example 2. If one eye becomes totally blind (c2= 0) while 
 the other remains uninjured (ci=0.65), the modified acuities are: 
 
 c/ = n X ^' = 0.75 X ^ = 0.75. 
 
 c./ = n X ^' = 0.75 X ^ = 0. 
 
 Cmax.= Ci^ 0.65 andc'max.= Ci'^ 0.75; table Y.,part IV., shows for 
 Ci and C2, E' = 55.519, the professional values are the same as in 
 the former example ; the earning ability is : 
 
 T-, C max. -Cj iX.00.Oiy ^^ rrto 
 
 Example 3. If both eyes suffer injuries of which the vision 
 of one eye is reduced to Ci = 0.50, and in the other to 0^=0.40, 
 where Cmax.= Ci=0.45 (professionally Cmax.= 0.50), the modified 
 acuities are according to the following formula : 
 
 , ^ Ci ,-, ^ ^ 0.45 „ -^ 
 
 c/ = n X - - = 0. 1 o X T^TT. = O.o2. 
 
 Di 0.60 
 
 c./ = n X — = 0. ( o X TT^- = 0.06. 
 T\-i 0.55 
 
 whose maximum c'raax.=C2'=0.5<j, which professionally represents 
 a valuation of (table V.)* 
 
 lOOcg' — 15 100 X 0.56 — 15 
 
 60 60 
 
 = 0.6833, 
 
 •The profpssional values belonging to the scientific visual acuities are obtained by the 
 following formula: 
 
 ^ lOOe— 15 ^ „ 100c— 5 
 
 Group I. — ~^ Group II. 
 
 60 "^ 45
 
 84 EXAMPLES. 
 
 To Ci and c-j Ijoloiiii- according to tabic \'., part IV., E =4:0.24:8, 
 from which we deduce the earning ability of : 
 
 ^ c'„,ax. E 0.6833 .... 46.248 „„ „_ 
 E = — = _^ =63.206. 
 
 Cna.v 0.50 
 
 ExAirPLE 4. It' both, eves be injured, but in sucli a manner 
 tliat one becomes totally blind ci^ 0, while the other is reduced to 
 Ca=0.30, the modified acuities of vision h.ave the following values: 
 
 c/ = nX" =0.75X^^^=0. 
 ni 0.65 
 
 c/ = n X — = 0.75 X [J-|^ = 0.41. 
 n-z 0.55 
 
 Cmax. =C2 = 0.30 (professionalh' = 0.25) and c'max.=C2'= 0.41 (to be 
 
 , . , 100X0.41 — 15 ", ,.,., X 1 , 1 • + ^ 
 
 replaced by ~ .r=r0.4o3 . . .) and as belonging to Cj and 
 
 02, we take from table Y, part IX.^ E' = 13.091, which quantity 
 allows us for the ability to earn : 
 
 g ^ c^,„xj' ^ 0.4 33 13.091 ^ 22 691 
 
 Cmax. U.ZO 
 
 §30. Group IV. In These C'ascs One Eye Was Or'ujinally Blind 
 and the titer WeaJc'Sighted. 
 
 We suppose that we have to deal with an individual whose pro- 
 fession has only low visual requirements (n^ 0.50). The one eye 
 is totally blind (ni= 0) while the other possesses a visual acuity of 
 n2-= 0.45. 
 
 If the seeing eye be injured and there remains only a visual 
 acuity of C2=0.25, because Ci = has to be used, there is c,„ax. =C2 
 ^=0.25 (professionally = 0.444 . . .)and the modified acuity of vision 
 c/ = 0, the maximum of both values will be : 
 
 C2'=n X — = 0.59 X ^'^l = 0.28 . . 
 na 0.45 
 
 which corresponds professionally with the figures: 
 100 X 0.28 — 0.5 
 
 45 
 
 = 0.511 
 
 To Ci and C2 belong according to table XA'L. part IV.. E' = 39.582; 
 the earning ability is therefore : 
 
 ^ c,„ax. E' 0.511 ... 39.582 ,_ ..^ 
 E= = ^ ... = 45.019. 
 
 Cmax. 0.444 . . .
 
 LOSS OF ONE EYE. 85 
 
 CHAPTER XIII. 
 
 THE LOSS OF ONE EYE THROUGH ACCIDENT. 
 
 Claims for damages in the case of accidental loss of an eye are 
 •of frequent occurrence and we will therefore give this subject ex- 
 haustive consideration. 
 
 §;j1. Estimation of the Vision in the Case of the Loss of One Eye. 
 
 In Chap. A'l., § 11, p. , we gave the following professional 
 calculation for the binocular act of vision. Our object is now to 
 estimate in what manner the individual factors of the formula are 
 impaired in value by the total loss of one eye. The formula for the 
 binocular act was : 
 
 ^, = CV?V (mi m2 ms m* iHo me) (m/ m/ ms' m/ nis' ms) 
 In the case of the loss of one eye, the central acuity (C of our 
 formula), is so little affected that the slight loss from the taking 
 away of the vision in one eye may be ignored. The clearness of 
 sight is just as good in monocular vision as in binocular. Ze- 
 hender (54-, p. G28) says that the. one-eyed condition does not offer 
 any ohstacles for following a trade from the visual point of view, 
 but this expression should be understood as only pertaining to the 
 visual acuity and not to the other factors. "We, therefore, put the 
 visual acuity in such cases with the valuation of the trade. 
 Of course, we must remember that diminution of the acuity 
 a little below the scientific standard but not encroaching on. the 
 trade limits, should not be regarded as injury incurring a liability, 
 for we have shown in Chap. YI., § 12, that a visual acuity of 0.75 — 
 0.50 should be regarded professionally as normal. In professions 
 with higher visual demands, a visual acuity of 0.75 is regarded as 
 normal equals 1, and in trades with smaller demands a visual 
 acuity of 0.50 is regarded as normal equals 1. If the injured per- 
 son liave a visual acuity of 0.75 or 0.50 we should not immediately 
 state that his working powers have sulfV'Vcd l)ut sliould examine into 
 the visual requirements of his trade. If we Ijelieve, that the voca- 
 tion requires fine vision, we would regard a visual acuity of 0.75 
 as normal. l)ut if the eye work is less. 0.50 may be regarded as 
 normal or 1. 
 
 The peripheric vision is but little affected through the loss of 
 one eye. because the extent of the monocular field of vision is but 
 a little narrower tb.an that of the ])inocular field. Only one seg- 
 ment is missing after the loss of one eve. According to our ar- 
 rangement of the entire field of vision into three concentric zones
 
 86 MUSCLE VALUES IN LOSS OF ONE EYE. 
 
 (})lato IV., Y\g. 1), the loss would be one-sixth of the whovc field 
 (eitlicr the blue or the red part of the drawing.) Therefore, after 
 the loss of one eye five-sixths of the field would remain which Ave 
 
 would insert into the formula as w — V 
 
 r 6 • 
 
 The action of the muscles will be materially impaired, because 
 estimation of distances, stereoscopic vision and judging of dimen- 
 sions are dependent upon binocular vision and are lost when it is 
 disturbed, but these functions are only temporally lost. A child 
 losing an eye at an early age, learns immediately to estimate dis- 
 tances, dimensions and relations of objects; an adult recovers more 
 or less of these functions, and as a rule in a very short time ; for di- 
 mensions, distances, etc., are known to him through his former ex- 
 perience Avith binocular vision. The muscular sense becomes more- 
 developed for the remaining eye, and the estimation of distance* 
 and size of objects is restored. Although Moorcn (29) disregards that, 
 our OAvn rather consideral)le experience Avould alloAV us to relate of 
 numerous persons who finally had these functions restored so that 
 they were ultimately able to estimate distances, the form and the 
 relation of objects just as well as persons Avith tAvo eyes. Similar 
 experiences have been noted by other authors (Guillery l-i, p. 215).. 
 Besides this, avo find enough one-eyed persons in every trade Avho can 
 do their duties as Avell as those Avho have tAvo eyes. In an examina- 
 tion (Xieden, 31), of 85,000 miners in Bochum. 310 one-eyed per- 
 sons Avere found Avho could folloAv their trade as Avell as the others. As 
 a result of this examination the management of the mines in the 
 Bochum district does not noAV regard the one-eyed condition as an 
 obstacle for the mining trade, and one-eyed persons are accepted as 
 miners, and those Avho lose an eye Avhile working arc alloAved to re- 
 main. Under certain circumstances an exceptional individual may 
 be found Avho does not regain the functions in question to a suffi- 
 cient extent, but as a general rule the muscular disorders from the 
 loss of one eye are only temporary, and in figuring impairment of 
 the earning ability this should be considered. For a time Ave may 
 giA'e this impairment an expression in our calculation, but it should 
 be reduced or removed in calculating the latter conditions. One- 
 year is sufficient liberal allowance for the individual to adapt his 
 monocular vision to the demands of his profession. A re-examina- 
 tion and ncAv calculation may be made one year afterAvards, and the 
 parties interested in the case should be informed that the alloAvance- 
 Avould be less after one year. 
 
 To form the muscular action M into an arithmetical quantity, 
 Ave divide it into three separate functions, Avhich Ave intend to regard 
 as of equal value; {. e., 1, into the part for moving the right eye; 
 2, the left eye ; 3, the binocular part. For our purposes both eyes 
 must be regarded as of equal value. Wlien one eye becomes blind,, 
 the tliird part used to estimate distances, etc., is entirely omitted,.
 
 MONOCULAR BLINDNESS AND ABILITY TO COMPETE. 87 
 
 but the other two factors remain, even if one only has to do with 
 the movement of a blind eye or of a stump, for in the latter case 
 it serves as a support for an artificial eye. therefore, the muscular 
 action remaining in the case of loss of one eye would be entered 
 into the formula for the act of vision as: 
 
 r 
 
 ^M. 
 
 The formula for working vision in the case of monocular blind- 
 ness would be : 
 
 It should be remembered that in professions with higher visual 
 demands the visual acuity C should be regarded as 1 even if it is 
 only three-fourths of the scientific standard and in lower demands it 
 is considered as of normal value if only one-half of the scientific 
 standard. 
 
 §32. Estimation of the Ahilifij to Coinpctc after ttic Loss of 
 One Eye. 
 
 In estimating the ability to compete after the loss of one eye, 
 the impaired values of the different factors entering into the act 
 of vision should be considered (Chap. YIL, § 15). The value of 
 
 the visual field would be 1' P and of the musclar action f--M. 
 
 The central acuity, from the professional standpoint, is not con- 
 sidered to have suffered, but still there is an impairment of the 
 earning ability (Chap. YL, § 11, p. 33.) The formula for the 
 ability to compete is taken as a root value, as it is of less import- 
 ance than the others, and its exponent is made a changeable one, 
 to agree with the seriousness of the ocular injury, as we have shown 
 in Chap. VII. , § 15, p. 48. "We will l)rieffy refer to the^e condi- 
 tions : The ability to compete is dependent not only on the condr- 
 tion of the ocular apparatus of ihe particular individual but also, 
 and even much more, upon the judgment of the employer. Accord- 
 ing to the seriousness of the injury, the employer becomes more 
 rigid, and if one eye be lost will even refuse work on this account. 
 An employer may be willing to employindividuals with slight ocular 
 disorders, but will frequently draw the line with the one-eyed. He 
 may occasionally employ a one-eyed man for roiigh work, but for 
 finer work will always prefer a man with two eyes. There may be 
 exceptions, as there may bo employers who regard one-eyed individ- 
 uals as able as normal sighted ones, but a normal siiihted one will
 
 88 EARXIXG ABILITY IX MOXOCULARISM. 
 
 most always Ijo preferred. Tliese eoiulitions must not be overlooked 
 in order to do justice. 
 
 The ability to compete, according to our conception, is a proper 
 fraction, because it is a ])roduct whose factors are either proper 
 fractions or equal to 1. If a proper fraction be taken as a root we 
 are able to raise or diminish its value by choosing the exponent 
 of the root; with a raising exponent the root value enhances, and 
 vice versa. If we adaj)t the ability to compete in one case as the 
 10th root and in another as the oth root, in the first case the value 
 would be greater and in the latter smaller. Thus by enhancing the 
 ability to compete, tlic earning ability increases while the other way 
 it diminishes. If in the ease of slighter injuries we use the ex- 
 ponent 10; by taking a smaller exponent, for instance, o, to reduce 
 its own and the value of the earning ability, it would meet the re- 
 quirements of the loss of one eye in those trades having higher 
 visual demands, whereas for coarser trades we may take 7 as the 
 exponent. (See Cha]). YH., S I-'- P- ■+^)- In fl^(^ fii'>t case, we 
 would get for the ability to compete the following expression : 
 
 r^rii^P^ 
 
 M, 
 
 and in the second case 
 
 r'f^Wi^i. 
 
 M. 
 
 §33. Esiliiiafiuii of iJte Edniiiuj AhlUtij Where One Eye Be- 
 comes Blind . 
 
 X 
 
 According to the formula for the earning ability E = F + V K. 
 
 I. In professions with higher visual demands for the first year 
 after the injury : 
 
 B=-r^r^'r^^7Ff^; 
 
 and after the first vear: 
 E = IC 
 
 n^f-fw^Wff,
 
 FORMULA FOB EARNIXG ABILITY IJf MONOCULARISM. 89 
 
 II. In professions with lesser visual demands I'or the first year 
 after the injury : 
 
 --F^r^.rv"yy7y|^ 
 
 and after the first vear 
 
 E^icf|7fMfiV^«|y7y 
 
 M. 
 
 The calculation of these formulas has been made, by the as- 
 sistance of our curves, so simple that it is reduced almost to com- 
 mon multiplication. Let us figure the first formula: 
 
 E = 
 
 ^^ij^w^p'r^T^'^ju. 
 
 C the ceutral maximal visual acuity remains 1; l/-— pmay be 
 
 read on plate A' without difficulty; as more convenient we change 
 the fraction % into a decimal — 0.833, and V 0.833 P according 
 
 to our curves equals 0.913. V M 'j^ing' changed into a decimal 
 
 0.666, is found on plate Y. as 0.004. The equation for the ability 
 to compete* would thus be : 
 
 should be first figured into its single factors before we can find the 
 total value in plate III.; when we do this, we get for the central 
 
 acuity ^- the value equals 0.r)0; |/ ^ p = 0.913 aud 
 
 i 
 
 1/2 
 
 w -- M. = 0.904. The equation for the ability to compete would 
 
 O 
 
 5 _ ^ ___ ___ fi 
 
 thus be: K 0.50 X 0.913 X 0.904= V 0.4127 and this figure we 
 
 yrj _j_ Q 4 
 F P r M *'^^ factors 
 
 Cj and Cg should ahvii.v.s be replaced by their professional valuation.
 
 90 PERCENTAGE OF LOSS IN MONOCULARISM. 
 
 find on plate V., curve 3, the valuation equals 0.838. We state 
 again the original formula : 
 
 which has been reduced to : 1 X 0.913 X 0.838 = 0.69145, which 
 in percentage is 69.145 per cent., which is the full earning ability 
 and therefore its impairment is 30.855 per cent. Should Ave have 
 worked this equation out entirely by figures, we would have found 
 the values 69.097 per cent, and 30.903 per cent., which differ imma- 
 terialh" from those given by our curves. This example shows that 
 our curves simplify the calculation without materially changing 
 the results. 
 
 According fo our calculations for trades with Irigher visual de- 
 mands ice find that a one-eyed person after being cured of the ocular 
 disease has an impairment of the earning ability amounting to 
 30.903 per cent., and after one year of 21.960 per cent., while for 
 vocations demanding less vision the values would be 21 .315 per cent, 
 and 18.3SS per cent. Of course, it would be left to the manage- 
 ment of the Insurance Companies as well as to the physician to 
 change these proportions more or less according to the circumstances 
 of the case. Approximately we may say that a one-eyed person has 
 lost 30 per cent, of his earning ability for the first year after the 
 accident and 20 per cent, afterwards for the higher class of trades 
 and for the lower class the proportion would be 21 per cent, for the 
 first year and IS per cent, thereafter. Certainly there is a difference 
 between the individual who has been employed in fine handiwork 
 and one doing common manual labor, and justice demands that a 
 difference should be made in judging the indemnity. The system 
 in vogue was an unfair one, as it over-estimated the valuation for the 
 loss of one eye, the Imperial Insurance Office (3) having given 
 33 1-3 per cent, indemnity. Heddiius (18) had fixed the indemnity 
 at 25 per cent.; Groenouw (12) accepts the sliding scale as made 
 by Magnus, his values fluctuating between 20 and 30 per cent., and 
 are therefore very close to the indemnity proposed by Magnus ; but 
 they must be regarded solely as arbitrary estimations and not the 
 result of exact calculations as have been given in this book. Ex- 
 amination of all one-eyed persons in the iron and steel trades in 
 certain districts in Germany showed that there was an actual im- 
 pairment in the amount of work done and the wages earned of 26 
 per cent, at the highest (Magnus, 26). Examination of the Miners' 
 Association in Halle a. S. (41) showed only 20 per cent. 
 
 All these facts speak for a revision of the 33 1-3 per cent, rate 
 now granted by the German Insurance offices. No real difference 
 should be made for the values of the right or the left eye, although 
 it is shown that the left eye is injured much more frequently (Ot-
 
 GRADUAL LOSS OF SIGHT IX OXE EYE. 9] 
 
 linger 33, p. TO) ; the left eye being injured in 60.2 per cent and 
 the right in 39.8 per cent. It would be perhaps well for the work- 
 jnan after losing the less endangered right eye to avoid vocations in 
 which injuries to the eye are frequent. 
 
 Our valuations of 30.903 per cent, and 2T.315 per cent, admit 
 after one year of a reduction, because those muscular functions 
 whicli were formerly executed by both eyes are partly or entirely re- 
 stored. The iigures of 21.97 per cent, or 18.39 per cent, should be 
 regarded as the maximal limit to which the damage may be reduced. 
 This reduction should not be obligatory in every case but the in- 
 dividnal should receive full consideration. In the case of older 
 men, a reduction may perhaps never be made because an old man 
 will never acquire new functions as will the younger one. The in- 
 telligence of the person is a factor and the profession itself should 
 play a role as regards this reduction of damage, depending upon 
 the visual demands of the vocation. In the case of smaller ocular 
 demands we need not be so considerate. 
 
 A further important question is whether the sudden total loss of 
 one eye does not demand a different valuation for the earning ability 
 than gradual growing blindness on one side. Accidental blindness 
 may be caused in different ways; either the eye may be injured to 
 such an extent that sight is immediately lost or the injury produces 
 a diseased condition leading gradually to the loss of vision. There 
 are numerous cases in which passable visual acuity exists for some 
 time after the accident and blindness only develops after several 
 years. Such cases occur from blows upon the head causing rupture 
 of the posterior coats of the eye, causing ultimate detachment of 
 the retina through cicatricial contraction. Iron and copper splin- 
 ters in the interior of the eye may, after one or two years, cause 
 ))lindness. Sudden blindness in one eye has certain ocular conse- 
 (|uences which make the following of the profession more difficult 
 for the injured, /. e., the judgment of distances, etc., and should be 
 considered in estimating the impairment of the earning ability. If 
 the one-sided blindness develops gradually, the lapse of time per- 
 mits the injured person to adapt himself to the ocular consequences 
 of being one-eyed. It is, therefore, not more than fair to consider 
 these conditions in figuring the impairment of the earning ability. 
 We would, therefore, figure the impairment of the earning ability in 
 :i case of gradual loss of sight at the lower rates above given. There- 
 fore the {mpainiient of the earning ahlliti/ from the gradual loss 
 of the ^ight in one eye following an accident in trades of higher 
 risval demands is 21.97 per cent., in professions icith lower visual 
 demands 18.39 per cent. 
 
 There Avas a time when 50 per cent, was regarded as the valu- 
 ation for the loss of one eye (Mooren 29; Golebiewski 10, pp. 129 
 and 241). But this is only a matter of history, for when the sub- 
 ject of economic damage from the loss of one eye was first preached, 
 the valuation of the two eyes was placed at 100, and one-half
 
 92 DANGER OF BLINDNESS IN MONOCULAHI.S:\r. 
 
 or 50 per cent, taken off for one eye. There was no scler.- 
 tific ophthalmologic investigation of the question, and it was 
 believed that the factors for fixing the amount of an- 
 nuity or damage sliould be looked for mainly in the 
 philanthropic-philosophical and not in the ophthalmologic pro- 
 fessional sphere. Zeliender's (.53) 33 1-3 per cent, and Jatzow's 
 (19a) 40 per cent, are estimations ))ased upon psychic factors. The 
 executive boards of the insurance offices and societies generally pre- 
 fer a much lower indemnity (Moses 30, p. 23). It is very likely 
 that the present 33 1-3 per cent, rate will share the fate of the 50 
 per cent, rate and soon will be replaced by a scientific standard such 
 as we have given it. Our methods are based upon scientific principles 
 and give the workingman of all classes pro rata indemnity corre- 
 sponding to the amount of the damage to their working powers. 
 The employer certainly finds in our system a protection against un- 
 fair claims of the employed. The badly injured person is really 
 better off under our S3'stem, for our "total disability of earning" be- 
 gins with a visual acuity of below one-seventh to one-twentieth, 
 whereas the old system total disal)ility was when the vision was 
 under one-hundredth. It is, therefore, just and fair for both em- 
 ployer and employed. 
 
 §34. Conccrninr/ the Supposed Greater Danger of a One-Eyed 
 Person Becoming Totally Blind and Its Relations to In- 
 demnity. 
 
 Perhaps the reader, in our calculation of the impairment to 
 the earning al)ility, may have already missed any reference or con- 
 sideration of the ultimate blindness or of the greater danger of be- 
 coming blind for the one-eyed person, upon which has been laid 
 such stress by Zehender (53, p. 269). We do not consider, as he 
 does, that this danger under all circumstances is double that of the 
 normal person, for the risk is but little greater. For instance, the 
 most frequent cause of blindness 1)etween the ages of 15 and 45 
 years is atrophy of the optic nerve (Magnus 24, p. 24G) and from 
 45 to 60 it is glaucoma; but we must remember that it is the gen- 
 eral rule for atrophy of the nerve to be double-sided. The causes 
 of one-sided atrophy are very rare and are very different patho- 
 logically from the binocular ones. There is precisely the same dan- 
 ger from this disease. Zehender's philantrophic feeling brought 
 him in glaring antagonism to statistics. All he should have said 
 was, that the possilnlity of becoming blind in certain diseases and 
 especially in certain injuries of the eyes is greater in the one-eyed 
 person, for, when the normal human being loses one of his eyes by 
 an accident, he. of course, retains the sight of the other, Avhile the 
 one-eyed person in losing his one eye becomes totally blind. Theo- 
 retically there is nothing to be said against this conclusion, but prac- 
 tically it is not of much importance. Our experiences show that 
 but few one-eyed persons lose their other eye through an injury
 
 DANGER OIT TOTAL BLINDNESS. 93 
 
 and, at an}- rate, these are so few that there is certainly not double 
 the danger of becoming blind. Magnus {2-iL, p. 184) states that 
 only once within the last eight years has he seen a one-eyed person 
 whose sound eye was injured by an injury ; a fact Avhich is surpris- 
 ing in view of the numerous losses of one eye of normal-siglited. 
 Wiirdemann, practicing in a manufacturing district where ocular 
 accidents are common, has seen but two eases of the loss of the re- 
 maining eye of a one-eyed person by accident within the last ten 
 years. The general experience of other practitioners will surely 
 support the above statements. We do not think that this question 
 should allow of additional indemnification in relation to fiffuring 
 the accident insurance or the annuity to be granted in any case to 
 workmen. Accidents to the remaining eye are more rare than to 
 persons who have two eyes, for in the first place they have learned to 
 be particularly careful to shield the remaining eye from injury and 
 to use it properly. We know one-eyed persons in many vocations, 
 in some of which the liability to ocular accidents is frequent, for in- 
 stance, workmen in stone quarries, in mines, in machine shops, etc., 
 but we have never heard from any one that the concern about his one 
 eye hindered him in his profession. Complaints of one-eyed per- 
 sons are generally quite different and refer to disorders in judging 
 distances, etc.; often such persons, who try to exaggerate their in- 
 jury, use other means than the concern regarding their remaining 
 eye. We must, therefore, exclude the danger of becoming blind 
 under all circumstances; in calculating the impairment of the earn- 
 ing ability of the one-eyed person the question of sympathetic in- 
 flammation should be considered from the same point of view, but 
 this is so important that wo will treat it in a separate chapter. 
 (Chap. XVI.)
 
 94 INJURIES TO LENS. 
 
 CHAPTER XIV. 
 
 §35. Accidental hijuries of the Crystalline Lens. Aphal-ia. 
 
 Tn injuries of the crvstallirie lens we have the peculiar condition 
 that as long as the injiin- lasts and the opaque lens stops the fur.c- 
 tiou of siffht. there is no doubt regarding the extent of the impair- 
 ment to the earning ability, but as* soon as the injured lens is 
 taken out by an operation which clears the pupil and vision returns, 
 then difficulties appear in the calculation. We have had occasion to 
 s-tudy many opinions and decisions in order to make satisfactory 
 judgment of the results of aphakia, upon the Avorking powers. If 
 one eye be normal and the other became aphakic through the loss O'f 
 the lens, the unequal refraction of both eyes renders the vision prac- 
 tically monocular, as the lensless eye is so hyperopic that a concert 
 of action of both eyes for professional use cannot be had; even 
 though the refraction be neutralized by convex glasses it cannot 
 work together with the sound eye. and the subject will always pre- 
 fer to dispense with the visual acuity on the lenseless side and work 
 with the normal eye. We, therefore, as long as the other eye re- 
 mains sound, regard one-sided aphakia in the same manner as that 
 of an individual having suffered important injuries to the visual 
 acuity Avhile the visual field and the muscles remain normal. This 
 assertion cannot be changed by the fact that eventually the visual 
 acuity of the aphakic eye mav be one-half or more; for if the in- 
 dividual cannot make use of this acquired acuity of vision in the in- 
 jured eye. his success in earning remains exactly the same as if the 
 visual acuity were not sufficient for use. Therefore we put mo- 
 nocular aphakia in the same position as the eye whose central acuity 
 is impaired to a high degree and reduced to 0.15 in professions with 
 higher, and to 0.05 in professions with lower ocular demands. But 
 we do not consider such an eye in the same relation as one which is 
 blind, for it forms, as Fuchs says (8a), "A reserve for the future." 
 But if the operative removal of the lens had not given a satisfactory 
 result regarding regaining good vision, such an aphakic eye would 
 not represent a prospective reserve for the future and should be con- 
 sidered as professionally blind. Thus the valuation of the relations 
 of the aphakic eye to the earning ability may be made upon sound 
 principles and with due regard to the individual peculiarities of the 
 ease. Tables T. and A^I. of part lY. give information regarding 
 the impairment of the earning ability in the case of one-sided 
 aphakia. The conditions are as follows : If an aphakic eye has a 
 visual acuity of 0.15 and over, in professions with higher visual de- 
 mands, and of 0.05 and over, in professions with lower visual de- 
 mands, and if the other eye remains normal, the impairment to the 
 earning ability would be 6.G9 per cent. But if the aphakic eye has a
 
 APHAKIA. 95 
 
 visual acuity below 0.15 or 0.05, depending upon the character of 
 the vocation, tlie impairment of the earninu- ability would be in the 
 first case 21.9 per cent, and in the latter ca.se 18.3 per cent (tables 
 v., and yi.. part IV.) These figures may be reduced to 15.5 per 
 cent., depending upon individual circumstances. For instance, if 
 the injured person is young and gets along easily with the changed 
 ocular conditions, the lower figure may be chosen ; the employment 
 of the injured person, his mental capacity and other factors will 
 play a role in choosing the higlier or the lower figures. These are 
 all conditions which should be considered in every case and left to 
 the decision of the trade boards or the physicians. The foregoing 
 refers to cases Avhere one eye remains sound; but if a man loses a 
 lens and the uninjured eye was previously weak-sighted, the con- 
 ditions are certainly different. If the uninjured eye cannot be used 
 for working purposes, tiie aphakic eye has to be estimated as if the 
 individual had been one-eyed. We here start from the fact that 
 the impairment of the earning ability is determined bv the central 
 acuity of vision Avhich the aphakic eve has regained. If the origi- 
 nally weak-sighted and uninjured eye is still able to earn, we have 
 to regard, in the professional estinuition, the extent of the central 
 acuity which both eyes possess. The eye whicli is used and which 
 possesses the higliest degree of acuity must be regarded as nio-t 
 fitted for earning while the other should be regarded as excluded 
 from work on account of the difference in the refraction ; the calcu- 
 lation is then made according to the principles put down in Chan- 
 ter XII. 
 
 There are still cases possilde, and we know of such, in whicli an 
 individual who became aphakic on one eye through an accident lias 
 later lost the remaining eye through another accident. The calcu- 
 lation of the impairment of the earning aliility would then have 
 to start from the central acuity of vision of the aphakic eye 
 which is fully explained in tables Y. and VI.
 
 96 IXJUKIES TO EYELIDS, ETC. 
 
 CHAPTER XV. 
 
 §3G. Injuries of the Eyelids, Conjunctiva and Cornea. 
 
 Traiiniatisms of the eyelids^ eoujimctiva and cornea may hinder 
 vision and their inflnence may he measured by the diminution of 
 the central acuity and the other factors of the visual act. We have 
 shown how burns may lead to extensive symblepharou and hinder 
 the ocular movements. In one case Magnus notes where the symble- 
 pharon was entirely relieved by operation, the eyelid remained thick- 
 ened, reddened and without eyelashes and the conjunctiva was read- 
 ily irritated. The disfigurement of the lower lid was such that the 
 patient could only get new work with difficulty and when he obtained 
 a job would soon have to give it up again, as the least irritation 
 produced a flow of tears which made continuation of work impos- 
 sible. Xotwithstanding that he had almost normal visual acuity 
 he had to be regarded as imj)aired for work. The valuation of such 
 a case had to be left entirely to the physician. We would here 
 warn against over-estimation of disfigurements ; it frequently hap- 
 pens that persons who hare lost one eye by a serious accident are not 
 satisfied with the annuity, indemnity or amount of insurance that 
 has been paid them and on account of disfigurement may claim a 
 higher rate, which in certain cases has been given to them. Mag- 
 nus does not consider such a course justifiable, for by his method 
 in the valuation of the loss of one eye, the disfigurement connected 
 therewith is already considered. We have done this in our previous 
 pages by giving the proper valuation in such cases to the ability to 
 compete.
 
 DANGER OF SYMPATHETIC 0PHTHAL:MITIS. 97 
 
 CHAPTER XVI. 
 
 §37. Should the Danger of Si/ in pathetic Ophthalmitis he Consid" 
 crcd in Estimating the Impairment of the Earning Ability'? 
 
 The possibility of resultant sympathetic disease in the uuiniured 
 eye has been brought up many times in medical and trade assembly 
 circles and in the law courts in estimating the impairment of the 
 earning ability. A number of authorities have considered that this 
 factor was of considerable moment in allowing an increase of the 
 rating; especially if there is a foreign body in the eye there is 
 even a disposition to give these conditions an expression in the 
 amount of the rating. We do not think that this danger should 
 influence the amount of the impairment allowed of the earning 
 ability. The possibility of being insured against sympathetic in- 
 flammation should be undertaken by the laborer himself, the same 
 as one pays a premium for fire insurance, if it is to be considered 
 at all. Such a relation between the employer and the employed 
 cannot be thought of; but if there was positive danger of future 
 sympathetic inflammation it might possibly be considered in calcu- 
 lating the impairment to the earning ability, if it really exerts a 
 hindering influence upon the workman's powers ; for instance, if the 
 man has to be exceedingly careful not to heighten that danger or to 
 hasten the outbreak of inflammation and thus has to limit the 
 amount of work or his working hours, an addition to his annuity 
 or indemnification might be justifiable and these conditions should 
 be considered. But the factors which affect the outbreak of sympa- 
 thetic ophthalmitis are not to be looked for in the performance of 
 the work and are not favored through the uses of the eye connected 
 with working life. This has been shown by experience. The youth- 
 ful eye which has not been used very much in working seems to Be 
 more exposed to sympathetic ophthalmia than the older eye. The 
 danger of sympathetic ophthalmitis is greatest in the first few 
 months after the injury of the other eye. and then it materially 
 diminishes. From the oculist's standpoint, the danger of sympa- 
 thetic ophthalmitis cannot be regarded as limiting the earning 
 ability, for this danger may be entirely removed if the patient sub- 
 mits to the operation proposed by the physician.
 
 98 ]NJl'I!I1;.S of the COIiXEA. 
 
 CHAPTER XVIL 
 
 §38. Injuries: of the Conica ThroiKjh Splinters of Iron or Foreign 
 Bodies. 
 
 Injury to the cornea through splinters of iron or emery is per- 
 haps the most common accident. Special ditficulties are not found in 
 applying our rules to such conditions. !Most frequently the cornea 
 is injured hy snuill particles of metal, and such cases arc common 
 in every oculist's practice and are of daily occurrence in ophthal- 
 mologic clinics. As a rule cases are immediately cured after re- 
 moval of the foreign hody and the little scars left are too insig- 
 nificant to exercise a detrimental influence upon the visual acuity. 
 Of course, many such accidents may have occurred and the cornea 
 be spotted with such small cicatrices, but in the course of time the 
 "workingman usually adapts himself to the increasing loss of vision 
 and does not feel the loss professionally. There are only excep- 
 tional cases that might be hindered in work by such accidents, and 
 the results are best estimated l)y the rules pertaining to the esti- 
 mation of the visual acuitv.
 
 IMPAIRMENTS OF ACCOMMODATION. 99 
 
 CHAPTER XVIII. 
 
 §39. Accidental hiipainnoits of the Acconnnodation. 
 
 Loss of accommodation without other injuries of the eyes are 
 very seldom caused by an accident. They mostly develop from 
 serious contusions of the head, especially of the forehead, contusions 
 of the iris, etc., and are much more frequently one-sided than 
 double-sided. They may exist without changes of the pupil, but 
 usually there is mydriasis. Such injuries should not be allowed 
 lasting pecuniary compensation, because we are always able to 
 replace the lost accommodation by litting convex lenses ; and as the 
 accident insurance law does not indemnify the lost function itself, 
 but gives a pecuniary compensation only when the earning ability 
 has sufFered, the impairment of the accommodation is surely not 
 within the bounds of the accident insurance law, although claim for 
 small damages might be allowed. There are conditions which are 
 in favor of granting at least a small indemnity : for instance, if there 
 be one-sided paralysis of the accommodation as well as of the pupil, 
 thedazzling and the dimness of the images may cause inconvenience; 
 but these symptoms ultimately pass away, for the sul)Ject becomes 
 used to the condition, even though at first he is hindered by such 
 symptoms. One-sided paralysis of the accommodation may be reme- 
 died bv the use of convex glasses; if the injured person opposes 
 wearing these, it is his own look-out, for if he throws away his 
 chance to regain the lost function, by a little inconvenience like the 
 wearing of glasses, he should not have a right for an indemnifica- 
 tion based upon the loss of earning ability. Where there is loss of 
 accommodation, the individual character of the case should be con- 
 sidered by the physician, insurance companies and the courts.
 
 100 OCULAR DISEASES. 
 
 CHAPTER XIX. 
 
 §40. Common Diseases of ihc Eyes of Local Oriyln That Impair 
 ihe Earning Power. 
 
 In addition to the subject of injuries to the earning ability 
 caused by traumatism, it has been deemed well to give a brief 
 resume of common diseases of the eyes of local origin that may 
 impair the earning power. In doing this we quote largely from 
 Hansen. (IT) 
 
 Acute inflammation of lids and conjunctiva being transitory 
 seldom leads to more than transient disability. The visual power is 
 decreased in proportion to their intensity. By reason of pain, swell- 
 ing photophobia and discharge, the patient has no earning power 
 during their continuance. 
 
 Chronic blepharitis and conjunctivitis without actually lowering 
 the acuity of vision, prohibit sustained near use and cut down the 
 number of daily working hours and proportionately the income. 
 
 Acute inflauimation of the cornea of one or both eyes totally 
 disables. 
 
 Chronic inflammation of the cornea of one or both eyes totally 
 disables. 
 
 Opacities of the cornea of one eye reduce the earning power not 
 more than 30 to ]8 per cent. (If one eye be rendered entirely 
 blind for economic purposes by reason of corneal opacity, it may be 
 treated as a case of monocular blindness, the impairment of the 
 earning abilitv for which ranges between 18 and 30 per cent.. 
 Chap. XIII., § 33, p. 90.) 
 
 Opacities of the cornea in both e3'es reduce th2 earning power 
 according to the visual acuity. 
 
 Acute iritis of one or both eyes totally disables fnr periods of 
 six weeks or longer. 
 
 Chronic iritis with posterior synechia? reduces earning capacity 
 according to the visual acuity, modified by the number of working 
 days or hours according to the peculiarities of the case (50 per 
 cent, by Hansell). 
 
 Incipient cataract of one eye, no reduction. 
 
 Advancing cataract of both eyes reduces according to the acuity 
 of vision remaining and is subject to continuous retrogression. 
 
 Complete cataract in both eyes completely disables, but after 
 successful operation on one eye the case is relegated to the catgory 
 of refractive cases. The earning power is restored according to 
 the vision regained for far and near. Hansell cites a patient 
 operated upon for cataract who stated that his earning power had 
 been gradually reduced from $18.00 per week to nothing. For sir
 
 OCULAPv DISEASES. * 101 
 
 mouths after cataract extraction his vision had equalkd 20 jc and 
 he had earned $9.00 — 50 per cent. loss. Lately he has vision with 
 a new correction 30|xv and has been able to command his old 
 wages. 
 
 A^itrcous opacities of one eye do not decrease the earning power, 
 nnless due to the presence of a foreign body causing irritation and 
 photophobia preventing full working hours, with danger of sympa- 
 thetic ophthalmia. 
 
 Vitreous opacities of both eyes decrease the earning power ac- 
 cording to the visual acuity plus the liability to total loss, which 
 juay be estimated at 50 per cent. more. 
 
 Detachment of the retina spontaneously or in myopia of one 
 eye'may be reckoned as total loss of that eye plus the probability 
 in the latter of total loss and total disability. Spontaneous or idio- 
 path.ic detachment of the retina of one eye is rarely followed by a 
 similar affection in the other, hence the probability of total loss is 
 le?s. 'I'he contrary pertains, however, where it follows as a conse- 
 quence of scleral stretching and chorioidal atrophy of myopia, whtn 
 the earning power is seriously menaced. The choice of occupation 
 is rendered difficult, since those demanding prolonged near use of 
 the eyes and straining and stooping positions must be declined. 
 
 Other diseases of the retina, the result of purely local causes and 
 limited to one eye, do not decrease the earning power. 
 
 Double central retinal chorioiditis reduces the earning power to 
 that of the average laborer, although the periphery of the fields 
 may be intact. Exceptions must be made when the earning power 
 depends upon intellectual rather than ocular acuteness. 
 
 Constitutional, acquired, or hereditary ocular disease, such as 
 albuminuric retinitis, retinitis pigmentosa, tubercular choroiditis, 
 syphilitic affections of the cornea, iris, vitreous and fundus tissues, 
 optic nerve atroph}', progressively reduce the earning power in 
 direct proportion to the loss of vision until the patient's death or 
 total disability. 
 
 Congenital color blindness debars the individual from army, 
 navy and railroad service, but from few practical pursuits and only 
 by limiting the selection of occupation does it interfere with his 
 earniug power. The estimate of the degree is purely arbitrary, but 
 probably does not exceed 1 per cent. 
 
 We compute (Chap. IX.. § 19, p. 58) the loss of earning 
 power from peripheral limitation of the fields thus : 
 
 Loss of 30 degrees Xo loss of e. p. 
 
 Loss of 40 degrees 20 per cent, loss of e. p. 
 
 Loss of 60 degrees 45 per cent, loss of e. p. 
 
 Peripheral limitation of one field only entails loss of e. p. of 
 10 per cent. 
 
 In homonymous hemianopsia Loss 30 per cent. 
 
 In bitemporal hemianopsia Loss 20 per cent. 
 
 In binasal hemianopsia Loss per cent.
 
 102 OCTLAR DISEASES. 
 
 Diplopia from monocular paralysis irremediable by prisms but 
 removed by occlusion of one eye brings the patient into the category 
 of the one-eyed, but since a variable amount of time must elapse 
 before the individual is able to resume his previous occupation and 
 to regain his old skill, he suffers a loss during this time of his earn- 
 ing capacitv of 18 to 30 per cent. (/. c, economic monoculism is 
 produced; see Chap. XIII., § 33, p. 90). 
 
 Paralysis of associated movements and double complete ophthal- 
 ]noplegia externa completely disables. 
 
 Errors of refraction deserve but scant attention in this paper, 
 since they are for the most part remediable, and the individual is 
 subjected to the annoyance only of his dependence on spectacles for 
 the full nse of his eyes with good vision. This is an inconvenience, 
 but does not decrease the earning power except as applied to a few 
 occupations. In the absence of disease persons with any kind of 
 regular defects can be restored to full earning power. In the case 
 of an incorrectil)le accommodative and muscular trouble by which 
 an individual is incapacitated from the full nse of his eyes, the loss 
 of earning power vrill equal the number of hours daily that he is 
 unable to work and may be estimated at 50 per cent, of his full 
 capacity. Conical cornea and irregular astigmatism not being sub- 
 ject to full correction by lenses diminish the earning ability accord- 
 ing to the loss of visual acuity. 
 
 Foreign bodies in the interior of the eye totally incapacitate for 
 a variable numlier of weeks and are in the great majority followed 
 by the loss of the eye. If removed before the stage of chronic irri- 
 tation sets in and the danger of sympathetic ophthalmia is not pres- 
 ent, the individual goes into the list of the one-eyed. If allowed 
 to remain the earning power is lessened 25 per cent, and in many 
 cases finally 100 per cent. 
 
 Foreign bodies in the cornea are readily removed usually with- 
 out permanent cicatrices. Before extraction the earning power is 
 reduced 100 per cent. The sudden loss of one eye incapacitates to 
 greater degree for a time than the gradual loss, because the indi- 
 vidual loses all judgment of space and he requires time to learn 
 anew the relation of objects to each other and their size and shape, 
 since the mental conceptions are changed. Among the trades that 
 require the higher grades of vision the damage to the earning power 
 in the gradual loss of one eye is 22 per cent., in the lower 18 per 
 cent. Zehender (54) says that after the loss of one eye only two- 
 thirds of the earning capacity remains. ]\Iooren (29) adds to this 
 the loss of binocular vision 8 to IG per cent., according to tlie dan- 
 ger of the occupation.
 
 PART THIRD. 
 
 Estimation of the Pecuniary Loss to the Individual by 
 Reason of Visual Imperfections.
 
 104 WAGES AND AGE OF W0I!K:\IEN". 
 
 CHAPTER XX. 
 
 §-il. Estimation of the Pecuniary Loss to the Individual hij Rea- 
 son of Visual Imperfections. 
 
 In the foregoing we have estimated the economic damage in the 
 form of percentages. Xow it remains to apply these ratings to the 
 conditions met Avith in daily life. 
 
 Money being the world's medium of exchange and of valuing a 
 man's work or time, we must reduce the economic damage in each 
 individual case to its value in dollars and cents or the monetary 
 medium of the country in which the compensation for damage may 
 be sought. It goes without saying that the value of men's time and 
 wages differ greatly, not only in different trades and professions, 
 but even the various members of the same trade receive varying 
 wages. 
 
 If we wish to exactly estimate the damage to the individual case, 
 we must, therefore, figure with the compensation that the individual 
 himself has heen getting and his probable future earnings. It must 
 bo allowed that this may be done in the case of artisans and the 
 working classes generally, and that this estimate may be legitimately 
 used as a basis with which to calculate the pecuniary loss he may 
 sustain by reason of lessened working and earning ability. In the 
 case of professional and business men, who do not receive regular 
 wages or a stipulated income, it might be considered. strict justice 
 to the defendant to take the average earnings of the class to which 
 the plaintiff may belong as a basis upon which to figure the in- 
 demnity. 
 
 It should be likewise considered that an old man cannot lose (as 
 regards earning ability) as much as a younger man, for the elder 
 has fewer prospectiveyearsof employment and consequent less money 
 equivalent than the younger. Thus the age of the plaintiff should 
 always be considered. It may likewise be taken for granted that the 
 average earning life begins at 15 and ceases at 65 years ; that in the 
 case of a business or professional man the wages will be doubled 
 every tenth year until cessation of working life ; that in the case of 
 working men this doubling will occur for the first two periods of 
 five years and afterwards the usual rate will be maintained until at 
 the age of 50, and 15 years thereafter though competition of younger 
 men and natural infirmities of this period of life then will be a 
 certain reduction in the wages. Exceptions to this estimate must 
 be made in the case of girls and women, since their working years 
 are fewer and their increase of earnings does not follow the same 
 rule as' that of men; many, perhaps the majority, being employed in 
 shops, mills and offices and in such positions that increase of skill 
 and experience are not rewarded by increase of their income.
 
 AGE SCALE. 105 
 
 Hansell assumes (1?) that a professional or business man will 
 double his earnings every ten years, provided his mental and physi- 
 cal health is preserved, and that he has average intelligence, in- 
 dustry and ambition. He considers that when the earning jwwer 
 of the individual falls below GG per cent, of the average earning 
 capacity, that promotion with increase of income cannot be reckoned 
 and that when SO per cent, of the visual power is lost the man is 
 no longer in a position to earn the income that was his before, and, 
 therefore, not onlv receives no increase, but his wages thereafter 
 may diminish; and if vision be reduced to counting fingers at 1-3 m. 
 (Magnus 0.15 to 0.05) the loss is 100 per cent., the individual 
 earning nothing and also becoming a charge upon his family or the 
 community. The doubling of the earnings for each decade maybe ap- 
 plied as a principle to most business and professional men, but in the 
 ease of laborers and artisans, who receive no promotion after having 
 attained a certain grade, it must be modified in respect to the 
 doubling of wages or income every tenth year. This permits of a 
 decided simplification of the computation, for as Hansell says : (17) 
 if a man earns $20.00 a week, and will continue to earn that amount 
 during the remainder of his working years, his loss will depend 
 upon the age at which the incapacity begins and its degree. 
 
 The following table, which agrees roughly with the mathemati- 
 cal estimations of ^lagnus, has been empirically figured by Hansell : 
 
 Visual Acuity. Loss of Earning Capacity. 
 
 ^%0 
 
 Y or 20 per 
 
 cent, 
 
 2«/^0 
 
 Y " 33 
 
 " 
 
 ^5^00 
 
 Y " 50 
 
 a 
 
 -%60 
 
 Y " 66 
 
 it 
 
 20/ 
 /200 
 
 Y " 80 
 
 a 
 
 ^00 
 
 4.75" 95 
 
 a 
 
 ling fingers at Y m. 
 
 Y5 " 100 
 
 a 
 
 By adjusting Hansell's age scale for the pecuniar}' earnings to 
 the estimation of the actual damage figured by the method of Mag- 
 nus we may arrive at an exact mathematical estimation of the 
 economic damage to the individual for the loss of vision in any 
 given case. In the following tables we give the earning power in 
 dollars and cents for the five decades of earning life. 
 
 Table C is adapted for the professional and businesss class 
 whose earnings as a rule increase until their retirement from busi- 
 ness. 
 
 Table D is for the artisan classs whose earnings remain about 
 the same during adult life and at the end of the working period 
 are usually subject to decrease. 
 
 Table E is for the laboring classes whose earnings are subject to 
 much the same law as that of the artisan.
 
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 EXCErTlONS TO 01" H RULES. 109 
 
 In cases where ihe blame of an accident may be laid upon the 
 second party or where, through previous business agreement, an 
 employer or insurance company has arranged to pay a fixed sum or 
 a pension in case of accidental injury, the amount of the indem- 
 nity should be in accordance to a definite schedule based upon the 
 average wages in the vocation to which the individual may belong. 
 It should be remembered that partial loss of vision not exceeding 
 25 per cent, in vocations having higher visual demands and not 
 exceeding 50 per cent, in those with lower demands does not injure 
 the earning ability to any degree. Indemnity, for actual disability, 
 therefore, should be granted only those whose eyes are damaged be- 
 yond reparation to a greater extent than above named. 
 
 It is only in vocations that have visual requirements that a 
 close estimate of these visual values may be made. In those classes 
 of business life whose followers are not engaged in manual labor, 
 whose business capacity relies more upon brains than iipon actual 
 handiwork, our rules cannot always apply, for even a lalind man 
 could work with monetary advantage in some trades and business ; 
 biit for the laborer, for the artisan and for those professions in 
 which the visual perceptive faculties are necessary, our rules and 
 tables may be deemed fitting. By adjusting the age scale for the 
 pecuniary earnings, to the percentage of the actual damage as fig- 
 ured by the method of Magnus, we may arrive at an exact mathe- 
 matical estimation of the economic damage to the individual for 
 the loss of vision in any given case. 
 
 It may be well to discuss the value of vision. This may be 
 summed up in one sentence, "'Sight is priceless, and, lil'e lionor, is 
 not a marl-etnhle commodity." Even the mere perception of light is 
 of inestimable value to a person who is economically blind and its 
 value to him cannot well be calculated. Does this fact conflict with 
 our propositions ? We do not think it can be considered, as we are 
 not dealing with any arbitrary value that might possibly bo placed 
 upon the sense of sight, but sole!}' with the earning capacity 
 of the eyes, which has to do with the amount and quality 
 of remuuerative work and the duration of working life. Can we a]i])lv 
 our rules to the case of non-workers, for instance, to infants, chil- 
 dren and those whose business does not require eye siuht, or can we 
 figure upon the ambition or possible prospects of advancement in 
 any other profession than that in which the person is employed? 
 It is self-evident that we can not. For instance, one of the children 
 in a family may some day become a millionaire, whereas one of his 
 brothers may ever remain a common laborer. There is no means of 
 foretelling the future . AVe can only figure with facts, and thus our 
 rules and estimations are based upon the compensation of th':' 
 person before the accident, and this is the only proposition that can 
 be received. Indemnification in the case of loss of sight from acci- 
 dents in children, in the majority of women, in persons who are
 
 110 VALUE OF SIGHT. 
 
 working hut U'lnporarily at some vocation, who ex{)eft to enter 
 another at some later period of lite, will have to he given, as here- 
 ioJ'ore, by arbitrary decisions of the courts. Such reasonings are 
 the common rules of bnsiness ; for instance, a man who has no in- 
 come whatever and can offer no collateral would l)e refused a loan 
 of money by any bank or business corporatii n. and could not obtain 
 any money except as an act of charity or for some extraneous reason 
 foreign to the rules of business. A ])erson with a small income, 
 for instance, earning $1,000 a year, would be able to borrow a cer- 
 tain small amount, for instance, $100, but another ]>erson earning 
 $10,000 a year would be able to borrow a vastly greater amount 
 upon his prospects. Thus for business reasons we can only con- 
 sider actual Avage earners to come under our rules. As accidental 
 injuries involving compensation for damages happen in a very large 
 majority of cases to persons of this class, all others may be looked 
 upon as exceptions and such cases may he left to be treated froiu 
 the philanthropic standpoint. 
 
 "While by this method of reasoning we are enabled to exactly es- 
 timate the amount of money that a given case may reasonably ex- 
 pect to earn provided he remain in the same business and exercise 
 ordinar}^ skill and diligence and hence accomplish an average 
 amount of work, it must be admitted that such figures are hypothet- 
 ical. However, such immense interests as those of the modern in- 
 surance companies and many other sociologic standards are success- 
 fully based upon the same principles and we must here be allowed 
 to use them. The result to be achieved by all our computations is 
 not the exact amount that a man will earn, but that which he may 
 reasonably expect to receive for his labors. 
 
 §42. Examples. 
 
 We will now take up some specific examples to illustrate the ap- 
 plication of our methods for determining the amount of economic 
 damage to the individual from ocular injuries. 
 
 Example 1. For our first example Ave take a case that often 
 comes up in the courts of law. An artisan whose business has high- 
 er visual demands, Avho has previouly had nornuil vision, receives 
 an injury to one eye Avhile working at his trade, by which the sight 
 of the injured eye is wholly lost, the vision in the other remaining 
 normal. The question then arises. Avhat economic damage has this 
 man sustained ? 
 
 We have shown that in the higher class of trades, during the 
 first year folloAving the accident, a one-eyed person has lost 30 per 
 cent, of his earning ability and afterAvards the loss may be reckoned 
 as 20 per cent. As a matter of convenience Ave Avill suppose that 
 this man is injured at the 30th year of age. and that he has been 
 ■earning for the previous five years $1,000.00 a year, Avith the expec-
 
 KXAMI'LES. Ill 
 
 tation of earning this sum annually until he is 50 years of age, when 
 for the next 15 years his average earnings, on account of disabil- 
 ity, due to a^e and the competition of younger workmen, will fall 
 to $750.00 a year and his working life is to cease at G5 years. His 
 total earnings for the balance of his life would then be reckoned 
 as follows : 20 years at $1,000.00 a year; 15 years at $750.00 a year ; 
 total, $31,250.00. For the first rear after the accident instead of 
 earning $1,000.00 he may expect a loss of 30 per cent. ($300.00) 
 and for the following nineteen ^ears instead of $19,000.00 he would 
 lose 20 per cent. ($3,800.00) and the following fifteen rears in- 
 stead of $11,250.00 he would lose 20 per cent. ($2,250.00)', making 
 a total loss for the thirty-fivo years of working life of $6,350.00. 
 which is his personal economic damage, an amount which he might 
 reasonably demand as an indemnity for the loss of earning ability 
 due to the accident if liability of the emplo3'er or djcfendant could 
 be proven. This sum should be used as the scientific basis for 
 settlement of contested cases : modified according to American laAV 
 by a reduction being made in favor of the defendant in case of 
 extenuating circumstances or contributory negligence and an addi- 
 tion made thereto for actual expenses incurred by the plaintiff dur- 
 ing his illness and damages for the pain and anguish suffered by 
 reason thereof. These amounts must ahvays be empirically esti- 
 mated by the courts.* 
 
 ExAiiPLE 2. If this man were injured at the age of 40 the same 
 method of calculation would give him a prospective compensation 
 of $21,250.00 for the balance of his earning life, instead of which, 
 for the first vear he Avould receive $700.00, for nine vears more, 
 $7,200.00, and for the fifteen years following $9,000.00; making 
 a total economic value of $10,900.00, a resulting economic damage 
 of $4,350.00. 
 
 ExA:\rrLE 3. If this man were injured at the age of 50, instead 
 of his prospective compensation being $750.00 per year for fifteen 
 years, or $11,250.00, for the first year after the accident he would 
 be earning 30 per cent, less, or $525.00, and for the following four- 
 teen years 20 per cent, less, or $8,400.00, making total economic 
 value^f $8,925.00 and total economic damage of $2,325.00. 
 
 By the use of different rates of compensation and different years 
 other examples could be readily given. The same method of rea- 
 soning applied to the loss of one eye in case of an artist or other 
 professional man would yield proportional results. The only dif- 
 ference in the calculations would bo the fact that such professions 
 usually become more remunerative as the person grows older. In 
 the ease of the common laborer, the only differences would be the 
 lower rate of compensation and the figuring of his economic loss 
 
 •Seven thousand doHarn has lieen recently awarded in Texas for the loss of an eyi-. 
 Court Civil Appeals Texas, I'.iOl, De La Vergne RefriK'-ratin^i Mafhine Co. vs. Stahl.
 
 112 LXA^IIT.KS. 
 
 at 20 per cent. I'or the first year after the accident and IS per cent, 
 thercal'ter. 
 
 We will now cro on to the calcnlations involved in more complex 
 cases where the same principles arc to be used as those which have 
 been invoked for simple cases : 
 
 Example 4. AVe will take the case of an architect or draufi:hts- 
 man, in his 46th year of life, earning $3,000.00 a year, whose visual 
 acuity in one eye is reduced by an accident to 0.50, the other re- 
 maining normal. His profession demands good vision and he is in a 
 measure handicapped for some of his work, especially that of fine 
 draughting. We will proceed to work out this case from the be- 
 ginning and will, therefore, recapitulate our formula: 
 
 X 
 
 In this case the maximum remains unchanged because this is 
 the higher visual acuity of the sound eye=l. V^ p the visual field, 
 
 4 
 
 and y M the muscular action remain unchanged ; the three factors 
 each representing the value I. In this case the unknown quantity 
 is the ability to compete. 
 
 F 
 
 '^'■p'-yYVM. 
 
 ' — - — ~- being the aritlimelical proportion of the central visual 
 
 acuity of both eyes. Ci,the uninjured eye remains = 1; Cs the in- 
 jured eye should be reduced to 0.50 of the scientific value 0.5, of 
 the scientific standard. Looking now on plate I. on the absciss for 
 the scientific value 0.5, trace this line upwards until we meet the 
 ecnomic curve II. which is for vocations having higher visual 
 demands, and from the point Avhere the line cuts the curve 
 we go to the left and find there on the ordinate the economic value 
 of the scientific estimation for the acuity of vision. This is 0.58; 
 inserting this value into the arithmetical proportion of the acuity 
 
 i. 1 .1 . , C, + C, , 1 + 0.58 ^ ^n rri • 
 
 for both eyes, into ' we have =0.79. This we m- 
 
 X 
 
 sert into the factor \ ^^^ V P V M : we then have 
 
 . f 0.7^ 
 
 2 
 
 4 
 
 9 VYVIa
 
 EXAMPLES. 1 13 
 
 in which V P and \ M are each ^=^1 ; the whole value is then 
 
 r 
 
 0.79 X 1 X 1. 
 
 As this is a slight injury, the ahility to compote is only 
 
 partly impaired, so we make tiie root exponent X=10. Tliis value 
 1(1 
 
 V 0.79X1X1 'wo can find in phite II., curve Y., where we look on 
 
 tlio absciss for the value 0.T9, trace the line from there upwards 
 
 until we meet the curve Y., going from there to the left oa the 
 
 ordinate we find the vahie 0.972. If we insert this value into the 
 
 formula we would find E=1X1X1X0.972, which multiplied by 100 
 
 gives the earning ability E = 97, 2 "b. This man being injured at 
 
 his 46th year, he would expect to have earned $00,000 during the 
 
 next twenty years. His earning ability being reduced to 97.2 ])er 
 
 cent, he would probably earn $58,320.00, which subtracted from the 
 
 reasonable expectations of his business, would leave the sum of 
 
 $1,680.00, an amount which he might expect as the indemnity for 
 
 the loss of earning ability due to the accident. 
 
 Exa:n[ple ."). Ir. the case of a printer who was originally weak- 
 sighted ; the vision of one eye ni = 0.05 and the other n; = 0.55 
 (scientific standard) ; eye 1 being uninjured (ci=0.05) while the 
 visual acuity of the other has been impaired by injury to c-.= 0.20. 
 He is in his 26th year and has been earning $1,000.00 annually and 
 would reasonably expect to earn this sum for the next 25 years, 
 after which his earnings through disabilities of his age, slow- 
 ness and consequent inability to compete would probably depreciate 
 to $750.00 a year, making the balance of the money that he might 
 reasonably expect to earn in the course of his life $36,250.00. Fig- 
 uring out the earning ability according to our modified formula :* 
 
 Cl „ „_ 0.65 r~- 
 
 Ci = n = 0. / o „ „^ = 0. ( o. 
 Hi 0.6o 
 
 c> 0.55 
 
 c, = n — =: 0.75 ':^ = 0.27, 
 
 n.. O.oo 
 
 the maximum ci=Ci =0.75 while we get for the maximum of the 
 real acuities e,„ax. = Ci = 0.65. The first value should be replaced 
 professionally bv 1 according to table B, p. 42 : the second bv 
 0.83 
 
 •These numbers are found by referring to table r>, part IV without calculation, 
 coiiiplicatetl cases as these (Cases 5 and ti) wouid be rarely found ia practice.
 
 114 KXAMPLKS. 
 
 To Ciandcai'iiriiishcs us tlie quniitity K, '=77. 079, the earning 
 aliilitv is tliereforo: 
 
 c'_.XE'_lX77.079_ 
 
 cmax. " 0.8333 -•'^•^^'^- 
 or a permanent disability of 7.505 per cent. The amount that be- 
 fore the accident be niiglit reasonably have expected to earn during 
 the balance of his life is $oG,"-50.00, 7,505 per cent, of wliich would 
 give $2,720.50, which should be the highest amount allowed as in- 
 demnity for the permanent loss of earning ability due to the acci- 
 dent subject to reduction for cause and to increase as determined 
 in Example I. 
 
 Example (>. In the case of a la])oi-er who was originally blind 
 in one eye, the other being weak-sighted (nr=0.45), Avho at the age 
 of 40 years suffered an injury to the seeing eye, and there remains 
 only a visual acuity ofc-2=0.25, because ci=0 has to be used, there- 
 is c,„ax. = C2= 0.25 (professionally = 0.444 . . .) and the modified 
 acuity of vision Ci=0, the iiiaximum of both values will be: 
 
 c/ = n -^= 0.50 JJ-t^ = 0.28 
 R'i 0.45 
 
 Avhich correspoiids professionally with the figures: 
 
 100 + 0.28 — 5 ^^,, 
 
 45 ^^-^^^ 
 
 To Ciand Cj belong, according to })late II.. or l)y calculating the root 
 
 Ei= 39.582; the earning abilitv is thertd'ore: 
 
 ^ c„„...E' 0.511 . . . 39.582 ,„.„ 
 E = = r^ , 4 , = 40.519 
 
 C ,nax. 0.444 
 
 the loss of the earning ability being 54.481 per cent. At the age of 
 40 years he would be earning $800.00 per year and might reason- 
 ably expect to earn this amount for 10 years, after M'hich, owing to 
 physical infirmities and increasing age, his earning powers \vould 
 probably be less, being reduced to $000.00 per annum; he would, 
 therefore, expect to earn, if he had remained in good physical 
 health, the sum of $17,000.00; after the accident his earning powers 
 being reduced to 45.519 per cent., he would be justly entitled to an 
 indemnity in proportion, which would be 54.481 per cent, of $17.- 
 000.00=$9,2G1.77, which would be likewise subject to increase or 
 decrease according to conditions of the accident as established by 
 Jaw. 
 
 ExA;MrLE 7. A traveling salesman, 45 years of age, who re- 
 cently consulted me had bi-nasal hemianopsia with a remaining 
 central acuity of 0.20 i]i both eyes. He stated that he had this con- 
 dition for a number of years and was enabled to do all his work 
 satisfactorily until recently when the visiuil acuity had failed, from 
 what he previously thought was normal, to 0.20. He was now able 
 to get about and sell some goods, but largely from memory, as he
 
 EXAMl'LHS. 115 
 
 could not read Ids biisincs.s catalogues and letters, and was about to 
 give up his business entirely. His income depended upon sales made 
 and was about $2,00U.00 a year. Thus for the balance of his work- 
 ing life his expectations would be for 20 years at $3,000.00 a year, 
 amounting to $40,000.00. According to his experience he was able 
 to do all his work until the visual acuity failed and we have 
 shown (page 60) that nasal hemianopsia does not necessarily in- 
 cur earning disability. Therefore, we Avould figure his economic 
 damage from the amount of the reduction of the visual acuity; the 
 scientific standard, 0.20, would have an economic equivalent of 
 0.38. Ileasoning from this economic loss of acuity and inserting 
 same and working out the formula, we find that the value of his 
 economic powers is about 30 per cent., Avhit-h lias a pecuniary valu- 
 ation of $600.00 ]ier annum, which agrees fairly well with his les- 
 sened expectationt^ of earning if his vision should remain as it is, 
 l)ut if it furtlier deteriorates he will be totally incapacitated. 
 
 Example 8. In the case of an iron moulder -iO years of age 
 receiving a blow upon his head which laid him up from work for a 
 year and caused permanent homonymous hemianopsia. From the 
 <^ffects of the accident, he being laid up for a year, afterwards being 
 obliged to take a lower position in the same line of work, which 
 ])aid him about one-third less, wo would figure his theoretic loss by 
 means of table on page 61 as 31.i) \h'v cent., which agrees near 
 enough M'ith the actual conditions of his work, for he was previously 
 earning $4.00 a day and afterwards was enabled to earn but $2.75 
 a day, the total economic damage can 1)e readily figured in this ca^e 
 as in the foregoing. 
 
 Examples of such character might be multiplied and cases cited 
 from the most simple form to that of the most complicated char- 
 acter. The foregoing are surely sufficient demonstration of the 
 fact that the percentage of economic loss and its pecuniary equiva- 
 lent in any given case of ocular injury, may be readily ascertained. 
 The diagrams and tables offer an easy method for this mathematical 
 calculation. In but few cases will it be found necessary to figure 
 out the formula in full, for reference to the proper table in part IV. 
 will at once give the percentage of earning ability. The relative 
 values ot the visual acuity, tlu^ \isnal Held and the ocular muscu- 
 lature must certainly be estimntcil liy a scientific examination of 
 tlie eyes, preferablv liy nii Dculist : tbese having been obtained the 
 other factors, the age and business of the workman and his wages 
 may Ix^ introduced into the formula and the probable pecuniary 
 ]iersona1 damage therel)v r(>adily calculated. Competent practi- 
 tionei's of law or medicine oi- insui-ance officials mav by thcs > 
 methods determine with exactness, in a nuinner fair and just to all 
 parties, the amouni of damage to the earning abilitv of their clients 
 which may have occurred as a result of accidental injuries to tlio 
 eyes, and this should be <-(»nsidei-ed tlie ]irinci]-yal factor in the settle- 
 ment of le<ral claims.
 
 PART FOURTH. 
 
 Tables for Estimation of the Different Forms of Damage 
 to the Visual Earning Ability. 
 
 Tables I to VI. Injuries to the Visual Acuity. 
 
 Tables VII to IX. Injuries to the Visual Field both Uncomplicated and 
 Complicated with Damage to the Visual Acuity. 
 
 Tables X to XII. Uncomplicated and Complicated Damages of the Ocular 
 Muscles. 
 
 Tablfs XIII to XXII. Various Forms of Damage in Monocularism.
 
 Earning Ability and its Impairment. One Eye Normal, the 
 Other Injured but not Blind. 
 
 TABLE I. 
 
 Vocations with Higher Visual 
 Demands. 
 
 The full professional visual 
 acuity corresponds with the scien- 
 tific standard 0.75; the ability to 
 
 in 
 
 compete is figured with Y until the 
 \nsual acuity falls to 0.15, then 
 
 with ] or y. 
 
 TABLE IL 
 
 Vocations with Lower Visual 
 Demands. 
 
 The full professional visual 
 acuity corresponds with the scien- 
 tific standard 0.5; the ability to 
 
 10 
 
 compete as figured with y until 
 the visual acuity falls below 0.5, 
 
 10 7 
 
 then with Y or Y- 
 
 Degree of 
 
 learning 
 
 Impairm't 
 
 Degree of 
 
 Earning 
 
 Impairm't 
 
 Scientific 
 
 of Earning 
 
 Scientific 
 
 of Earning 
 
 Acuity. 
 
 Ability. 
 
 Ability. 
 
 Acuity. 
 1—1.50 
 
 Ability. 
 
 Ability. 
 
 1—0.75 
 
 100 
 
 0.0 
 
 100 
 
 0.0 
 
 0.70 
 
 99.5 
 
 0.5 
 
 0.45 
 
 99.4 
 
 0.6 
 
 0.65 
 
 99.1 
 
 0.9 
 
 0.40 
 
 98.8 
 
 1.2 
 
 0.60 
 
 98.6 
 
 1.4 
 
 0.35 
 
 98.1 
 
 1.9 
 
 0.55 
 
 9S.1 
 
 1.9 
 
 0.30 
 
 97.5 
 
 2.5 
 
 0.50 
 
 97.6 
 
 2.4 
 
 0.25 
 
 96.7 
 
 3.3 
 
 0.45 
 
 97.1 
 
 2.9 
 
 0.20 
 
 96.0 
 
 4.0 
 
 0.40 
 
 96.6 
 
 3.4 
 
 0.15 
 
 95.1 
 
 4.9 
 
 0.35 
 
 96.0 
 
 4.0 
 
 0.10 
 
 94.2 
 
 5.8 
 
 0.30 
 
 95.4 
 
 4.6 
 
 0.05 
 
 93.3 
 
 6.7 
 
 0.25 
 
 94.7 
 
 5.3 
 
 If the acu- 
 
 
 
 0.20 
 
 94.0 
 
 6.0 
 
 ity falls be- 
 
 84.4 
 
 15.6 
 
 0.15 
 
 93.8 
 
 6.7 
 
 'low 0.05 
 
 or 
 
 or 
 
 If the acu- 
 
 
 
 without 
 
 81.6 
 
 18.4 
 
 itv falls be- 
 
 84.4 
 
 15.6 
 
 blindness. 
 
 
 
 low 0.15 
 
 or 
 
 or 
 
 
 
 
 without 
 
 78.0 
 
 22.0 
 
 
 
 
 blindness. 
 
 
 
 
 
 
 *In the German editions of Magnus' work Dr. Hugo Ilohr has carried 
 out the calculations to the thousandths of a per cent. The figures are too 
 conaplicated for practical use, and as our calculations are dependent large- 
 ly upon probabilities which are more or less variable, the American editor 
 has only accepted the calculations to 1-10 per cent, as jirinted in the follow- 
 ing tables; where there would be a fractional remainder less than 0.1 per 
 cent, it has been added to the amount of the impairment: on account of 
 this simplification the figures are slightly different than those in the II 
 •German Edition.
 
 Earning Ability and its Impairment, One Eye Bliod, the 
 Other Weaksighte<L 
 
 TABLE III. 
 
 Vocations -with Higher Visual Demands. 
 
 Full acuity of vision 1, corresponds with the scientific standard 
 0.75, and the ability to compete is figured with V. 
 
 Visual Acuity of 
 
 ■ 
 
 Impairment 
 
 lieduction Per- 
 
 the Weaksighted 
 
 Earninp: Ability. 
 
 of the 
 
 niiesible After 
 
 Eye. 
 
 
 Earuing Ability. 
 
 One Year. 
 
 0.70 
 
 62. 2 
 
 37.8 
 
 29.7 
 
 0.65 
 
 55.5 
 
 44.5 
 
 37.3 
 
 0.60 
 
 48.9 
 
 51.1 
 
 44.7 
 
 0.55 
 
 42.4 
 
 57.6 
 
 52.0 
 
 0.50 
 
 36.1 
 
 63.9 
 
 59.1 
 
 0.45 
 
 30.0 
 
 70.0 
 
 66.1 
 
 0.40 
 
 24.1 
 
 75.9 
 
 72.7 
 
 0.35 
 
 18.4 
 
 81.6 
 
 79.1 
 
 0.30 
 
 13.0 
 
 87.0 
 
 85.2 
 
 0.25 
 
 8.0 
 
 92.0 
 
 90.9 
 
 0.20 
 
 3.5 
 
 96.5 
 
 96.0 
 
 0.15 
 
 0.0 
 
 100.0 
 
 _ 
 
 100.0 
 
 
 TABL 
 
 .E IV. 
 
 
 ■^ 
 
 /ocations with Low 
 
 er Visual Demands 
 
 , 
 
 Full acuitv of vision 1, corresponds with the scientific standard 
 
 5 
 
 0.50, and the ability to compete is figured with V. 
 
 Visual Acuitv of 
 
 
 Impairment 
 
 Reduction Per- 
 
 the Weaksighted 
 
 Earning Ability. 
 
 of the 
 
 missible Aft^r 
 
 Eye. 
 
 63.5 
 
 Earning Ability. 
 36.5 
 
 One Year. 
 
 0.45 
 
 28.6 
 
 0.40 
 
 54.5 
 
 45.5 
 
 38.7 
 
 0.35 
 
 45.7 
 
 54.3 
 
 48.6 
 
 0.30 
 
 37.1 
 
 62.9 
 
 58.3 
 
 0.25 
 
 28.7 
 
 71.3 
 
 67.6 
 
 0.20 
 
 20.7 
 
 79.3 
 
 76.6 
 
 0.15 
 
 13.0 
 
 87.0 
 
 85.3 
 
 0.10 
 
 5.9 
 
 94.1 
 
 93.3 
 
 0.05 
 
 0.0 
 
 100.0 
 
 100.0
 
 
 
 
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 ENTIFI 
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 FOU 
 ISUAL 
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 ill
 
 TABLE VII. 
 
 Earning Ability and its Impairment in Disorders of the Visual Field with Nor- 
 mal Central Visual Acuity. 
 
 VARIETY (^F DEFECT. 
 
 
 fcc . 
 
 03X3 
 
 f Partial defects in one field ■] 
 
 I Concentric contraction of the field of | 
 
 1. { one eye i 
 I Loss of one temporal half of one eye | 
 t Loss of the full field of one eye J 
 
 ( Small concentric contraction of both ) 
 
 2. j fields reaching to 60° ( 
 ( Loss of the temporal half of both fields S 
 
 3. Hoinonymous hemianopsia dextra veJ 
 
 sinistra, superior vel inferior 
 
 4. Great concentric contraction of both 
 
 fields reaching 30° 
 
 5. Total concentric contraction of both 
 
 fields reaching to 5 per cent. 
 
 g ( Loss of the nasal halves of both fields } 
 ■ ) Loss of the nasal half of one field » 
 
 X 
 
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 K 
 
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 M 
 
 68.3 
 
 54.6 
 0.0 
 
 i— I o.S 
 
 9.6 
 
 20.0 
 
 3L7 
 
 45.4 
 
 100.0 
 
 1 100.0 0.0
 
 TABLE Vila. 
 
 Ability to Compete and Impairment of Visual Fields for Vocations with Higher 
 and Lower Visual Demands, Figured Separately. 
 
 Case. 
 
 RemainiDg 
 
 Fraction 
 
 of P. 
 
 5 
 
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 Higher demands (for 
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 7 
 
 K figured with V for 
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 ^ . Impairmeut 
 Earning ^f the Earn- 
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 Earninp; 
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 Impairment 
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 y—t 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 22 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 a3 
 
 
 , 
 
 ^ — ^> 
 
 
 /'^ 
 
 
 
 
 
 ^ G 
 
 
 
 a> 
 
 
 
 OQ 
 
 
 
 
 
 
 
 
 
 
 
 G 
 
 
 
 2 
 
 OD «= 
 
 
 ■13 
 
 
 OJ 
 
 
 
 
 
 
 
 
 
 
 'a3 
 
 2-3 
 
 
 
 — 
 
 
 
 
 i 
 
 
 *« 
 
 
 
 «n 
 
 QJ > 
 
 
 ^ 
 
 
 ^ 
 
 
 013 
 
 
 ' 
 
 
 
 
 
 T? 
 
 
 -►J -*^ 
 
 C X 
 in 
 
 > a, 
 
 '^ 2 
 
 
 
 
 G 
 c; 
 
 
 ■*J 
 
 
 ^ 
 
 
 fa 
 
 2 
 
 2 
 
 "0 
 
 'oq' 
 
 a> 
 
 CD 
 
 -3 
 
 
 -►J 
 
 
 c 
 
 
 c3 
 
 c 
 
 
 
 
 G 
 
 a 
 
 c3 
 
 
 
 
 m 
 
 2 
 
 
 G 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 •*j 
 
 
 
 
 
 
 
 fl 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 ^ 
 
 '-♦J 
 
 T3 
 
 c5 
 
 
 
 '^ 
 
 > 
 
 
 
 
 
 "3 
 
 c3 
 
 >< 
 
 
 
 
 
 d 
 
 
 
 
 
 
 
 
 
 
 
 -G 
 
 -G 
 
 H 
 1 
 
 > 
 
 03 
 -1-3 
 
 
 a 
 
 c 
 
 
 
 -1 
 
 
 
 
 
 "So 
 
 
 -g 
 
 Gh g 
 
 
 
 2d- 
 
 ? c 
 
 cS 
 G 
 bD 
 
 G 
 
 
 
 
 a> 
 
 
 *— H 
 
 (~; 
 
 =! C -C P 
 
 a: 
 
 
 
 
 G 
 
 C^ 
 
 rG 
 
 
 t3 
 
 CI 
 
 a; 
 
 
 J- 
 
 
 
 
 -►J 
 
 'f— < 
 
 *^ ?-) 
 
 ^ 
 
 C 
 
 
 -1-^ 
 
 4^ 1 
 
 ■ 
 
 
 
 tj-i 
 
 ^ ^ 
 
 ■+^ G 
 
 of 
 
 S-i 
 03 
 
 5r!'^ 
 
 
 
 -G «+-! 
 
 =^ 
 
 
 3 
 c3 
 
 
 
 
 00 
 
 
 
 
 
 u:;W 
 
 c3 
 
 
 
 
 
 c3 
 
 
 
 ID 
 
 
 
 
 
 CO 
 
 
 Pm 
 
 
 1— 1 
 
 CC 
 
 
 
 
 
 Eh 
 
 »d 
 
 CO 
 
 
 
 ^ 
 
 
 c<i 
 
 CO
 
 TABLE X. 
 
 EarDing Ability and Impairment from Non-Complicated Disorders of the Exter- 
 nal Ocular Muscles. 
 
 G - « 
 
 ^ ) > CD 
 
 KIND OF INJURY. 
 
 o o 
 
 o t>,.S 
 
 1—0.75 
 
 Paralysis of the muscles of only Resp. 
 
 one eye 1 1 — O.oO 
 
 Paralysis of the muscles of both 1 — 0.75 
 
 eyes; in the working eye only Resp. 
 
 one muscle is paralyzed yf. 1 — 0.50 
 
 Paralysis of the muscles of both I 1 — 0.75 
 
 eyes; in the working eye two Resp. 
 
 muscles are paralyzed ;K 1 — 0.50 
 
 Patalysis of the muscles of both I 1 — 0.75 
 
 eyes; in the working eye three Resp. 
 
 muscles are paralyzed ^ 1 — 0.50 
 
 Paralysis of the muscles of Ijoth 1 — 0.75 
 
 eyes; in the working eye four Resp. 
 
 muscles are paralyzed 'yi 1 — 0.50 
 
 Paralysis of the muscles of both 1 — 0.75 
 
 eyes; in the working eye five Resp. 
 
 muscles are paralyzed j^ 1 — 0.75 
 
 Paralysis of all the muscles used 1 — 0.75 
 
 by both or bv the working Resp. 
 
 eye .". , 1—0.50 
 
 75.4 24.6 
 
 71.8 28.2 
 
 67.5 32.5 
 
 62.3 37.7 
 
 55.8 44.2 
 
 46.1 53.9 
 
 0.0 100.0
 
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 U :p _ 
 
 ^ "5. 
 
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 g 
 
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 IC 
 
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 05 CO CO O CO 05 
 
 Tf TjH -.^ T^H CO C4 
 
 »o »o O ^3^ CO t>- '^ 
 
 '^ d d d Qo t^ CD 
 
 O »-i ,-1 
 
 O -* CO CD lO '^ O 
 
 "^ CD lo '*' CO c<i d 
 
 to 
 CO 
 
 d 
 
 »0 -^ "-^ CO CD t-- 
 
 c<i •.-H o cc CO CO 
 
 C<) <M (M ■— — ^ 
 
 0.40 
 
 00 T}< c- OC CO CD 
 
 CO i>^ id CO T-I |>I 
 
 (M <M (N C<I (M '-- 
 
 0.45 
 
 CO TT lO -^ O lO 
 
 id co' — <' ci CO ^ 
 
 CO CO CO -M (M (M 
 
 0.50 
 
 t^ CD CO -^^ GO ""T 
 
 — i Ci t-^ '^' d "5 
 -* CO CO co-ro OJ 
 
 0.55 
 
 CO OS (M 05 C~- lO 
 
 GO id CO d id d 
 
 '^ -^ ^ CO CO <N 
 
 2 
 
 d 
 
 O CO (?< -^^ CO CO 
 
 id (N d id d co' 
 
 lO lO TT -^ -Tt* CO 
 
 0.65 
 
 i>. r-- c<i o CD t>- 
 
 -^ 00 id — < id t^ 
 
 CD lO lO lO -^ CO 
 
 O CD C<J CO t^ t>. OS 
 
 •^ o6 ic ■>-<■ ?d' d ^ 
 
 O CD CD CD lO lO -* 
 
 i-O 
 
 -f 00 lO CC' 00 '— 
 
 id -- r^ (>i id CO 
 
 t— t^ CO CD lO -^ 
 
 a 
 a 
 o 
 
 
 OQ 
 
 ^ 
 
 ^ 
 
 t^ 
 
 s 
 
 c 
 
 a? 
 
 %^ 
 
 
 
 -»j 
 
 <<:; 
 
 o 
 
 a; 
 
 ^ 
 
 ai 
 
 a> 
 
 y 
 
 ^ 
 
 (T) 
 
 ti 
 
 >. 
 
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 O) 
 
 :, ;z; 
 
 
 «^ « g C 
 
 cu G § o 
 
 o i ^ ^ 
 
 ^ s ^^ 
 
 a; Ti ci 02 
 
 ^ O c 
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 ss 
 
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 > 
 
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 H •- ^ 
 
 C V 
 
 H .1 g 
 
 c 
 
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 c 
 
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 t^ -^ O lO OS 1-t 
 
 
 O CO CD to -*i -f 
 
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 'sj* t^ OS OS CD 00 
 
 
 -^ CO (M ^ OOO 
 
 o 
 
 »— 1 ^H 1— 1 .-^ 1— 1 
 
 o 
 
 lO ""^ '— CO CD t^ 
 
 C<l 
 
 (N — ' d CC CO CO 
 
 o 
 
 C^ (M (M -H 1-1 i-H 
 
 lO 
 
 OS -^ CO to CO OS 
 
 
 O OS t^ lO C<> CO 
 
 o 
 
 CO C<l (M <N (>J T~i 
 
 o 
 
 lO CO CO CO <M T-i 
 
 
 OS t^ lO (N OS ^ 
 
 d 
 
 CO CO CO CO (M (M 
 
 i 
 
 to 
 
 CO OS (M OS t^- to 
 
 CO 
 
 CO to CO OS to OS 
 
 o 
 
 -rri "^ -* CO CO CO 
 
 o 
 
 CQ Tt< cq CO CO OS 
 
 
 t^ ^ „ t^(M ^ 
 
 o 
 
 lO to to -^ "^ CO 
 
 to 
 
 CO O CO 00 o to 
 
 "Tfi 
 
 CD CO ~ -rf o: O 
 
 o 
 
 CD CO to to ■^ -^ 
 
 >- 
 
 
 = o 
 
 
 g "^ 
 
 '^i CO lO CO 00 i-< 
 
 -= o 
 
 lO 1— 1 t^ O-l LO CO 
 
 3 1 
 
 t^ t>- CO CD o -^ 
 
 Iri. 
 
 
 > 
 
 
 O) 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
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 rH 
 
 
 
 
 
 
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 ^ 2 S == ^ <t> 
 
 Hi 
 
 1— 1 
 
 uj a G o G S 
 
 G O O^ S § 
 
 ' 2? ^ 
 
 
 :T, o ° ^ oT. 
 
 ^ v. S « tc ^ 
 
 
 -tJ S«-. 
 
 03 <^ r-ii o o) <3j 
 
 (D G 
 E3 » 
 
 <l>'c3 <^ o^'o'^ 
 
 -^ 1 G 5 1 ^ 
 
 O; G G S i^ 3 
 
 1 gs ^ ;:s a 
 
 ^ S G S P a, 
 
 i ^.^ CG &: G 
 
 ^ 
 
 1 < 
 
 ,ps 
 
 pi 
 
 Hh 
 
 Ol
 
 a:^ 
 
 
 
 rj -o" 
 
 - ^ 
 
 
 C ^ 
 
 ^ 
 
 
 ^•S 
 
 
 
 rj S 
 
 ^ 
 
 
 <^ 
 
 0) 
 7-1 
 
 
 "3 2 
 
 3 „ 
 
 a 
 
 t—t 
 
 bf) 
 
 HH 
 
 <« 
 
 X 
 
 > Si 
 
 .22 
 
 (X] 
 
 
 
 J 
 
 
 a:> 
 
 PQ 
 
 ° o 
 
 S 
 o 
 o 
 
 o 
 
 < 
 
 c , 
 
 
 ^ . 
 
 -M 
 
 
 
 
 
 3 1 
 
 >^ 
 
 
 Q S 
 c '^ 
 
 c3 
 
 
 
 
 
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 CD 
 
 
 rJ:3 
 
 
 c » 
 
 H 
 
 
 
 
 
 
 
 
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 ^: 
 
 
 
 
 
 
 
 
 
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 t)C >■ 
 
 
 
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 cj O 
 
 lo 
 
 OO 
 
 •■; 
 
 diii 
 
 o 
 
 
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 <N 
 
 CD CO 
 
 o 
 
 05 
 
 lO 
 
 Oi ■•—1 
 
 (M 
 
 cod 
 
 o 
 
 tH CO 
 
 o 
 
 t^co 
 
 CO 
 
 
 
 ■■-(00 
 
 o 
 
 (M t^ 
 
 lO 
 
 00 CN 
 
 CO 
 
 dd 
 
 d 
 
 <M I>- 
 
 o 
 
 T-H 05 
 
 "^ 
 
 CO- 
 
 o 
 
 CO CO 
 
 lo 
 
 co-^ 
 
 "^ 
 
 CD CO 
 
 d 
 
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 1 o 
 
 (MOO 
 
 to ■* 
 
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 d 
 
 CD CO 
 
 =^ 
 
 OOC-1 
 
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 t>-(M \ 
 
 ■ lO 
 
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 (X5 
 
 —1 00 
 
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 00 T-l 
 
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 00 (M 
 
 c~- 
 
 oo; 
 
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 Oi 
 
 ':^ 
 
 
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 c^ 
 
 
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 ^ o 
 
 1 
 
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 >- 
 
 
 
 >l^ 
 
 
 
 
 
 
 P 
 
 
 ' i 
 
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 , 1 
 
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 >^ • 1 
 
 
 
 
 
 c: 
 
 7^ +^ 
 
 P 
 
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 rt ?i 
 
 > 
 
 hop 
 
 
 
 
 rt p 
 
 
 f^ 
 
 hH 
 
 
 >. 
 
 
 
 
 m 
 
 
 
 
 6> 
 
 
 
 
 c 
 
 
 
 
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 >« 
 
 
 
 
 
 
 
 
 
 
 
 
 ft 
 
 
 
 
 c 
 
 
 
 
 
 
 
 
 Ml 
 
 
 
 
 
 
 
 
 
 
 
 
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 c 
 
 
 
 
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 u 
 
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 e 
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 T3 
 C 
 
 E 
 
 ^ 
 
 
 
 Q 
 
 > 
 
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 « 
 
 l-H 
 
 > 
 
 a 
 
 > 
 
 
 &> 
 
 c 
 
 b 
 
 
 .£3 
 
 c 
 o 
 
 o 
 
 PQ 
 
 
 ~ 
 
 -I 
 
 <3 
 
 « 
 
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 •£ 
 
 H 
 
 S 
 
 U 
 
 5 
 
 
 ^ 
 
 ■a 
 
 c 
 
 
 
 
 
 
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 w 
 
 
 
 .53 
 
 n') 
 
 
 
 Q 
 
 c 
 
 n 
 
 > 
 
 a 
 
 M 
 
 ! to 
 
 oo 
 
 o 
 o 
 
 dS 
 
 o 
 
 Oi y— 
 
 
 
 
 CO —1 
 
 o 
 
 Ol 
 
 to 
 
 tH OS 
 
 T-l 
 
 C50 
 
 d 
 
 r-OO 
 
 o 
 
 00 <N 
 
 C<l 
 
 
 
 OiO 
 
 o 
 
 (Nt- 
 
 to 
 
 05^ 
 
 (M 
 
 d d 
 
 d 
 
 '^ to 
 
 o 
 
 CO t^ 
 
 CO 
 
 <M t- 
 
 o 
 
 »0 Tfi 
 
 to 
 
 oo 
 
 CO 
 
 
 
 '^ CD 
 
 o 
 
 CD CO 
 
 o 
 
 00 <N 
 
 ^ 
 
 to ■^' 
 
 o 
 
 t-(M 
 
 to 
 
 00 CN 
 
 ■^ 
 
 t^ (N 
 
 o 
 
 00 ^ 
 
 c 
 
 
 i to 
 
 (^ 
 
 1 d 
 
 (^ (^ 
 
 — ^ o 
 
 1 
 
 o 
 
 T-H 
 
 
 > 
 
 
 
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 o 
 
 
 
 << 
 
 
 
 ^^ 
 
 
 
 ec 
 
 
 
 =3 
 
 
 
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 bX) 
 
 
 
 
 
 
 
 
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 w 
 
 ^
 
 TABLE Xllla. 
 
 Earning Ability and Impairment if the Injury of One Muscle has to be Valued 
 Correspondingly Higher, in Special Vocations. 
 
 bb 
 
 a 
 "S 
 
 s 
 
 o 
 
 ■ 
 
 5 
 
 K figured with >' (higher de- 
 mands, only for more seri- 
 
 7 
 
 K figured with V' 
 mands, only 
 
 (lower de- 
 for more 
 
 t-i 
 
 a 
 
 lous nijunes. 
 
 ) 
 
 serious inj 
 
 uries.) 
 
 1—1 
 02 
 
 > 
 
 a 
 
 ■<3 
 
 
 
 
 
 
 s 
 
 o 
 <v 
 
 Earning 
 ability. 
 
 Impair- 
 ment. 
 
 Earning 
 
 ability. 
 
 
 Impair- 
 ment. 
 
 
 
 
 
 
 j 
 
 
 6 
 
 1 
 
 ■ 
 69.1 
 
 30.9 
 
 72.6 
 
 ! 
 
 27.4 
 
 5 
 
 K 
 
 65.5 
 
 34.5 
 
 68.9 
 
 
 31.1 
 
 4 
 
 X 
 
 61.2 
 
 38.8 
 
 64.7 
 
 
 35.3 
 
 3 
 
 5^ 
 
 56.2 
 
 43.8 
 
 59.6 
 
 
 40.4 
 
 2 
 
 K 
 
 49.7 
 
 50.8 
 
 53.1 
 
 
 46.9 
 
 1 
 
 1 / 
 
 40.4 
 
 59.6 
 
 43.5 
 
 
 
 565 
 
 
 
 
 
 
 
 • 
 
 100 
 
 
 
 
 
 100
 
 bX) 
 
 (X ^ 
 
 I -"-^ 
 
 <i» IS 
 
 C •-; 
 
 O -2 
 
 X > 
 
 PQ o 
 
 2 
 
 < 3 
 
 
 6 s 
 
 ^ c 
 
 < .2 
 
 C TS 
 
 <-> c 
 
 W _ 
 
 o 
 
 1—1 
 
 d 
 
 to 
 
 
 o o 
 o2 
 
 lO 
 
 o 
 
 o 
 d 
 
 op 
 
 id id 
 
 OS 
 
 0.25 
 
 11.6 
 
 88.4 
 
 0.30 
 
 CO 1-^ 
 1-1 GO 
 
 CO 
 
 d 
 
 26.7 
 78.3 
 
 o 
 d 
 
 34.9 
 65.1 
 
 0.45 
 
 43.5 
 56.5 
 
 0.50 
 
 52.3 
 
 47.7 
 
 lO 
 
 o 
 
 61.4 
 38.6 
 
 o 
 
 CO 
 
 d 
 
 70 8 
 29.2 
 
 0.65 
 
 CO tr- 
 
 - dc5 
 
 00^- 
 
 o 
 I- 
 
 d 
 
 90.0 
 10.0 
 
 -d 
 
 1—1 o 
 
 
 rt G 
 Wh^ 
 
 CU ^ 
 
 
 
 fcC 
 
 < :3 
 
 ?& 
 
 Q i: 
 
 E -^ 
 
 < 
 
 w 
 
 s. 
 
 
 
 M 
 
 X 
 
 > 
 
 H 
 
 > 
 
 u 
 J 
 
 
 aJ 
 
 
 OQ 
 
 o 
 
 c 
 a: 
 
 •-J 
 
 < 
 
 u 
 
 c 
 
 
 ,S2 'iJ .S 
 
 O 
 
 lO 
 
 <3 
 
 "3 
 
 o o 
 d2 
 
 0.10 
 
 8.1 
 91.9 
 
 d 
 
 ^GO 
 
 8 
 d- 
 
 28.4 
 71.6 
 
 0.25 
 
 lO lO 
 
 d d 
 
 CO CO 
 
 0.30 
 
 oo 
 
 T-;d 
 
 0.35 
 
 05 i-H 
 CO CO 
 
 o - 
 d 
 
 op 
 
 lO 
 
 d 
 
 -<t CD 
 
 CO 1-1 
 
 oo 
 
 2d 
 
 >. 
 
 ^ 
 
 -»J 
 
 ,o 
 
 a 
 
 -! 
 
 a> 
 
 
 
 hn 
 
 
 a 
 
 
 s 
 
 CS 
 
 &, 
 
 ci 
 
 a 
 
 l-H 
 
 w
 
 TABLE XVII. 
 
 Earning Ability and Impairment in Disturbances of the Visual Field of an Orig- 
 inally One-Eyed Person. 
 
 
 One-eyed condition in a One eyed condition in a 
 
 +3 
 
 professional sense. scientific sense. 
 
 
 Proliepsioual visual de- rrofessional vifcual de- 
 
 Variety ok De- ^13 
 
 mands, mands. 
 
 FECT OF ^ IS- ^ ^ 
 
 UAL Field. S ^ 
 
 Hig 
 
 1 
 
 her. Lower. Higher. | Lowt'r. 
 
 i5S 
 
 Visual Acuity. 
 
 Visual Acuity. 
 
 1—0.75 
 
 1—0.75 
 
 1—0 50 
 
 1—0.50 
 
 1—0.75 
 
 1-0.75 
 
 1—0.50 
 
 1-0.50 
 
 
 < 
 
 E'rning 
 \bility. 
 
 [mpair- 
 ment. 
 
 E'rning 
 Ability. 
 
 Impair- E'rning 
 nient. Ability. 
 
 Impair- 
 ment. 
 
 E'rning 
 Ability 
 
 Impair- 
 ment. 
 
 Loss of the na- 
 
 
 
 
 
 
 
 
 
 
 sal half, K 
 
 75.5 
 
 24.5 
 
 75.5 
 
 24.5 
 
 73.6 
 
 26.4 
 
 74.6 
 
 25.4 
 
 Small concen- 
 
 
 
 
 
 
 
 
 
 
 tric contract'n 
 
 % 
 
 67.7 
 
 29.3 
 
 70.7 
 
 29.3 
 
 68.5 
 
 31.5 
 
 69.8 
 
 30.2 
 
 L088 of tlie tem-1 
 
 poral half, | 
 Great concentric 2^ 
 
 contraction, ^ 
 
 reaeliing; 30°, J 
 
 
 
 
 
 
 
 
 
 60.4 
 
 39.6 
 
 60.4 
 
 39.6 
 
 57.7 
 
 42.3 
 
 59.2 
 
 40.8 
 
 
 
 
 
 
 
 
 
 TABLE XVIII. 
 
 Earning Ability and Impairment in Disturbances of the External Ocular Muscles 
 of an Originally One-Eyed Person. 
 
 
 9 
 
 One-eyed condition in a One-eyed condition in a 
 professional sense. scientific sense. 
 
 VARIETY OF 
 
 Professional visual de- 
 mands. 
 
 Professional visual de- 
 mands. 
 
 MUSCULAR - ^ 
 DEFECT. g ^ 
 
 Higher. Lower. 
 
 Higher. Lovrer. 
 
 1 a eg 
 
 Visual Acuity. 
 
 Visual Acuity. 
 
 
 f.s 
 
 1—0.75 
 
 1—0.75 1—0.50 
 
 1-0.60 
 
 1—0.75 
 
 1—0.75 1 1—0.50 1— 0..50 
 
 
 
 E'rning 
 Ability. 
 
 Impair- E'rning 
 ment. Ability. 
 
 Impair- 
 ment. 
 
 E'rning 
 Ability. 
 
 Impair-J E'rning Impair- 
 ment, i Ability, ment. 
 
 Loss of 1 mus- 
 cle, y. 
 
 Loss of 2 mus- 
 cles, jH 
 
 95.1 
 89.4 
 
 4.9 
 10.6 
 
 95.1 
 89.4 
 
 4.9 
 10.6 
 
 94.6 
 
 88.5 
 
 5.4 
 11.5 
 
 94.9 
 89.0 
 
 5.1 
 11.0 
 
 Loss of 3 mus- 
 cles, y. 
 
 82.6 
 
 17.4 82.6 
 
 17.4 
 
 81.2 
 
 18.8 
 
 ! 
 
 82.0 1 18.0 
 
 Loss of 4 mus- 
 cles, -y; [ 73.9 
 
 Loss of 5 mus- 
 cles, i X 1 61.0 
 
 26.1 73.9 
 39.0 1 61.0 
 
 26.1 
 39.0 
 
 71.9 
 58.4 
 
 28.1 
 41.6 
 
 73.0 27.0 
 59.9 i 40.1
 
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 132
 
 BIBLIOGRAPHY.
 
 BIBLIOGRAPHY. 
 
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 in Railroad and Steaniship Service. — Journal Ainer. Mcfl. Af<so.. I'JbO. 
 
 2. American ^ledical Association, Section on Ophthalmology. — Trans. 
 1900-1901. 
 
 3. Amtliche Xachrichten des Reichs-Versicherungsamts Nr. V. 1. 
 Miirz 1897, Seite 253 ff. und die Berufsgenossenschaft Xr. G,. 1897, p. 50. 
 
 4. Baudrv. S. Injuries to the Evo in Their ;Medico-Legal Aspect. 
 1900. 
 
 5. Becker. Anleitung zur Bestimnnmg der Arbeits-und Erwerbsun- 
 fiihigkfit nach Verletzungen. Fiir Aerzte. B?rufsgenossense]iaften und Ver- 
 sich?rungs-Anstalten. 4. Aulf.. Berlin, 1892. 
 
 6. Bell. Expert Testimony. 
 
 7. Berichte der Aerztekanuncv dcr Provinz Schlesien. III. Sitzung 
 voni 20. October. 1894, Seite 10. 
 
 8. Dienst-Anweisungen zur Beurtheilung der ^lilitar-Dienstlahigke'.t 
 und der Ausstellung von Attcsten. B.^rlin. 1S77. - 
 
 8. Fnchs. Lelirbuch der Augenheilkundc. 1889. 
 
 9. Grcenleaf. Evidence, p. 114. 
 
 10. Golebiewski. Aerztlicher Commentar ziim l'nfalls-\'trsicheruiigs- 
 gesetz vom (i. July. 1884. ]\lit praktischtn RAthschliigen zur Untersuchung, 
 Bchandlung und Beurtheilung von Unfalls-Verlctzten. Berl'n, 1893. 
 
 11. Groenouw. Ueber die Vermindeiung der ErwerbsfUhigkeit durch 
 Sehst.'irungen. Deutsche incdicinische \^'och(nschrift, 1893. Xr. 40-44. 
 
 12. GroenouAV. Anleitung zur Berechnung der Erwerbstilhigkeit bei 
 SehstiJrungen. Wiesbaden. 189(i. 
 
 13. Groenouw. Ueber die Berechnung der Erwerbsfiiliigkeit b?i Seh- 
 storungen. Deutsche. Medicinal -Zeitung. 1897, Xr. 21 und 11. Ueber die 
 Beurtheilung der Erwerbsfiihigkeit bei S.hstorungen. Deutsche Me lical- 
 Zeitu ng. 1897. Xr. 10. 
 
 14. Guillery. Ueber die Entschjidigungsanspriiche Einaugiger. Kli- 
 nische iMonatsblatter fiir Augenheilkundc. 1892. 
 
 15. Haab. Die wichtigsten Storungcn des Ge<ichtsfeldes. Au-^en- 
 iirztliche Unterrichtstafeln. heransgegeben von Magnus. Heft. V. Bres- 
 lau. 1893. 
 
 16. Handbuch der Unfall-Versicherung. Die Reichs-Unfall-Versicher- 
 ungsgesetze dargestellt von jNIitglitdern des Reichs-Versicherung^amts. 
 Leipzig. 1892. 
 
 17. Hansell, Howard F. Estimation of the Amount of Injury to the 
 Business Capacity of the Individual from Partial or Complete Loss of 
 Vision. Annals of Oplitlialmology, 1900. 
 
 18. Heddiius. Xoch ein \'orschlag zur Scluitzung der Erwerbsunflihig- 
 keit bei Augen-Verletzungen. Klinische Monatsblattsr fiir Augenhe 1- 
 kunde. 1895. 
 
 19a. Jatzow. I'cber die Bestimmungen des Procentsatzes der Erwerbs- 
 fiihigkeit bei Schiidigungen in Folge von L'nfall. Tageblatt der 61. Ver- 
 sammluno- deutscher Xaturforscher und Aerzte in Kciln. KiJln, 1889, 
 p. 209. 
 
 19b. Josten, zur Beurtheilung der f]rwerbs-Verminder>ing nach Augen- 
 verletzungen. Klin. ^Nbmat. F. Angenhkde. 1889, p. 526. 
 
 20. Kaufmann. Handbuch der Unfallverletzungen. Stuttgart. 18!)3. 
 
 21. Knies. L'eber die Centralen Stiirungen der willkiiiliihn Au>en- 
 mu-skeln. Archiv fiir Augenlieilkunde. 1891. Band XXIII.. p. 28. 
 
 22. Lewis. E.xpert Testimony. 
 
 23. Magnus. Die Blindheit. ihre Entstehun<i und ihre Verliiituno'. 
 Breslaii. 1883 
 
 24. Magnus. Leitfaden fiir Begutaclitunn' und B rcchnung von L^n- 
 fallsbeschiidigungen der Augen. Breslau. K'-94 und 1-97.
 
 136 BIBT.IOGRAIMTY. 
 
 25. MafTiius. Dio .Tii<ion(ll)lin(lli(>it. Wiesbaden. ISSi). 
 20. Majrniis. Die Kinaujiiykcit in ihien Beziehungen y.ur Eiwirls- 
 fahipkeit. Breslau, 1895. 
 
 27. Magim.s. Zur kritischeii Beleiiclitiing des GiOFiimnv'sclun Buchr s : 
 Anloitung zur Beieclimin<j der Erweibsfaliigkeit b(i Schstoningi'ii. l)e t- 
 sche ^Icdifinal-Zeitinig. 1897, Xr. 3; uiid Xr. 21. 
 
 28. !Magmis. Die p]rweibsbesch;idigaiiig hi i ^>l■l^Ist e'lies Auges. E'lie 
 kritische Beleuclitiing dev gegein\;iitig hen scbeiuleii \'eih;iltiiisse mit Vor- 
 sehliigpii fiir eine Reform derselhi'ii. Aeiztliclie S icliver8t:iiidigeii-Zeitunj^, 
 1897. Xr. 5. 
 
 29. ^looren. Selistthuiigcu uiul EiitscliiUliguiigs-Anspriiehe der Ar- 
 beiter. Diisseldorf. 1891. 
 
 30. Moses. Ueber den (Jrad der Erwerbsinifiihigkeit nneli \'erletzun- 
 gen eines Auges. Dissertatio Inanguralis. Breslavi. \S9d. 
 
 31. Xieden. Der Xystagnms der Bergleute. Wiesbaden. 1894. 
 
 32. Xorris and Oliver. System of Diseases of the Eye. 1899. Vol. II. 
 
 33. Ottinger. Zur Statistik der Augenverletzungen. Klinisehe Mo- 
 natsbliitter fiir Augenheilknnde. 1894. p. 75. 
 
 34. Sdii'lmiloh. llandbuoh der Mathematik. Enevklopiidie der Xatiir- 
 wissensehaften. Breslan. 1879-1881. 
 
 35. Sehmidt-Rim])lcr. Doppelseitige Hemianojjsie mit Sectionsbefund. 
 Arehiv fiir Angenlieiiknnde 1893. Band XXVI.. p. 181. 
 
 30. Sehmoekel. Ueber das Sehvprmfigen der Eisenbahn-Betrirbs-Beam- 
 ten. Zeitung des Vereins dentseher Eisenbahn-\>r\valtiingen 1894. Xr. 3-4. 
 
 37. Schrijter. Unfallsbeschadignngen des Sehvormogens nnd ilire Ab- 
 schUtzung. Antritts-Vorlesung. Ltinzig. 1891. 
 
 38. Sehvermiigen der Eisenbalm-Bediensteten. Eisenbahn-Veiordnungs- 
 blatt 1897. Xr. 2, Amtsblatt der kilniidiehen Eisenbahn-D'rfctien zu Bres- 
 lan. Xr. 20. 1897. 24 :Miirz. Aerztliehe Saehverstilndi->n-Zeitung, 1897, 
 Xr. 0. 
 
 39. Silex. I'eber Selipriifnngen 1)( i Eis?nb;ihnbeamt n. Beiliner Jirzt- 
 liches Correspondenzblatt. 1893. 
 
 40. Sinkler. Charles. See Baiidry. 
 
 41. Statistik iiber die Einiiiisrigen Arbeiter im Bezirk der Section IV. 
 (Halle a. S.) der Knappschifts-Bernfs-Gpnossenschaft. ^Monatsschrift fiir 
 Unfallheilkunde. 1894. Xr. nnd 7. 
 
 42. Steplien. Evidence. Section 117. 
 
 43. Tavlor. A. ^f. Evidence. Section 1417. 
 
 44. Taylor. A. :\I. The Law in Its Relation to the Physician. 1900. 
 
 45. Thomson. Wm. Detection of f'olor-Blindness. See Xorris-Oliver. 
 40. Von Woedtke. Unfall-Versicheriingsgrsstz vom (i. Jnli, 1884. 4. 
 
 Anflage. Berlin. 180O. 
 
 47. Walther, "Angennntersiuhungen an 2,500 Arb;itern."" Arehiv. f. 
 Aiigenhkde. Bd. XLIL. Heft 1 nnd 2. 1900. 
 
 48. Williams, Charles. The Vision of Railwav Employees. Journal 
 Boston Society of ^Fedicine and Science. Marcli. 1899. 
 
 49. Williams, Charles. The Vision and Hearing of Railwav Em- 
 ployees. 1900. 
 
 50. Wisconsin Reports. Vol. 101. p. 278. 
 
 51. Wiirdeniann. H. V. Tlie Economic Limitations of the Visual 
 Acuity in ^'ari()us Trades and Professions. See American ^ledical Associ- 
 ation Section on Ophthalmology, 1901. Trans. Journal Amer. iled. Assoc, 
 February. 1902. 
 
 52. Wiirdeniann, H. V.. and ^lagnus. H. Economic Valuation ofVision. 
 Annals of Ophthalmology. April. 1901. 
 
 53. Zehender. I'eber den zahlenmiissigen Aus Inn k der Erwerbsnn- 
 fjihigkeit gegeniiber der Unfall-Wrsicherungs-Gesellschaft. Klinisehe Mo- 
 natsbljitter fiir Augenheilkunde. 1889, p. 205. 
 
 54. Zehender. Zur Unfall-Versicherunusfrage. Klinisclie ^lonatsbat- 
 ter fiir Augenheilkunde. 1889, p. 531.
 
 ALPHABETICAL INDEX.
 
 INDEX. 
 
 139 
 
 ALPHABETICAL INDEX. 
 
 A, 
 
 Ability to compete, Definition of. 46 
 
 ■ — Foi iiiiila 40 
 
 — Estimation of 40 
 
 — in nionocularism . . 71 
 
 — Acquired 80 
 
 — Congenital So 
 
 — Older valuation of in mo- 
 
 nocularisni 91 
 
 — Part depending upon individ- 
 
 ual 47 
 
 — Part depending upon employer 47 
 
 — A factor of the earning ability 20 
 Absciss (see also plates I. and 
 
 V). . 42. 52 
 
 •Artisan classes 37, 107, 110 
 
 Accident insurance — 
 
 — German law 10 
 
 — Companies in America 14 
 
 — Methods of settlement 1.5 
 
 — Relation of physician to 21 
 
 — Officials' duty to determine 
 
 amount 21 
 
 Accommodation, Damage to... 44, 99 
 Accommodation, convex lenses in 
 
 paralysis of 45 
 
 Adaption 30 
 
 Allport, Investigations of vision 
 
 of railroad employees 40 
 
 — Division of railroad employees 
 
 into classes 39, 41 
 
 American Medical Association. 
 Transact. Section on Oph- 
 thalmology 11 
 
 Aphakia 94 
 
 Arbitrary fixation of payments 
 for visual losses by Ameri- 
 can insurance companies... 14 
 
 Arithmetical proportion IS. 32 
 
 Atrophia nervii optici, Danger of 
 
 blindness from 92, 97 
 
 B. 
 
 Baggagemen 3n 
 
 Baggagemasters 39 
 
 Bargemen 37 
 
 Baudry, Medical-legal aspects of 
 
 injuries to the eye 13 
 
 Becker. Estimation • of working 
 
 ability 28 
 
 Bell, Expert testimony 14 
 
 PAGE. 
 
 Builders 37 
 
 Brakemen 39 
 
 Brewers and Maltsters 37 
 
 Brickmakers 37 
 
 Bridge foremen 39 
 
 Bridge tenders 39 
 
 Binocular economic vision, For- 
 mula for 33 
 
 Blindness. Economic meaning of. ;j3 
 
 — Scientific meaning of 33 
 
 C. 
 
 Cerebral vision 30 
 
 Chemical workers 37 
 
 Cliimney sweeps 3y 
 
 Classes of railroad employees.. .39, 41 
 
 Color sense 24 
 
 Color blindness 101 
 
 Competition, difficulty of one eyed 
 
 men ' . . 87 
 
 Conjunctiva, injuries of 96 
 
 — • Inflammation of 100 
 
 Conductors, railroad 41 
 
 Cornea, staphyloma of 96 
 
 — Inflammation of 96 
 
 — Opacities of 96 
 
 — Injuries of 96 
 
 Curves. Geometric, for rendering 
 
 the calculations and simpli- 
 fying the f ormulcTe . . . . 42, 52, 55 
 
 — Showing scientific and the two 
 
 grades of economic visual 
 
 acuity (also plate I) 42 
 
 — For estimation of the factors 
 
 of economic vision (also 
 
 plate V) 52 
 
 Cyclops, from Groenouw's for- 
 mula 20, 29 
 
 Capacity for earning a living. . 26 
 Congenital defects. Adjustment 
 
 in ■ 31 
 
 Convex lenses in paralysis of ac- 
 commodation . .• 45 
 
 Cataract 100 
 
 Chorioiditis 101 
 
 Constitutional diseases 101 
 
 D. 
 
 Danger of blindness of one-eyed 
 
 persons 97
 
 140 
 
 INDEX. 
 
 Damages, ]Measure of 14 
 
 — Definition of 14 
 
 — Relation of physician to 17 
 
 — Relation of insurance officials 
 
 to 17 
 
 — Nominal .' 14 
 
 — Substantial, conipensatorv ... 14 
 
 — Exemplary, punitive, vindictive 14 
 Damage to visual acuity (see 
 
 tables, part IV. ; see also 
 
 visual acuity 30 
 
 — to visual field (tables, part 
 
 IV.) 30, 58, Gl, 03 
 
 - — to ocular muscles (tables, part 
 
 IV.) 101. 22. 30, 31. 44, 65 
 
 — to economic vision, etc 30 
 
 — to earning abilitj^ 24 
 
 — to working ability ....'....;.. 28 
 
 Day laborers 38 
 
 Deformitv resulting from acci- 
 dent. 4S 
 
 Despatchers 39 
 
 Diseases, local, impairing earning 
 
 power 100 
 
 Dutv of phvsieian 17 
 
 Diplopia . ." 101 
 
 Earning ability. Definition of . . . 26 
 
 — Formula for 28 
 
 — Factors of 26 
 
 — According to German law .... 26 
 
 — In normal health 28 
 
 ■ — How determined 26 
 
 — Foersters false estimation... 
 
 — Wagner's right estimation. . . . 
 
 — Hansen's empirical estimation 105 
 
 — Relations of visual acuity to. 32 
 
 — Relations of visual acuity to. 
 
 Avhen only one eye is injured 
 (see tables, part IV.) 
 
 — Relations of visual acuity to. 
 
 when one is damaged and 
 ' other blind (see tables, part 
 
 IV.) 
 
 Earning ability 11 
 
 — in loss of central visual acuity 
 
 of both eyes 33 
 
 — in loss of central visual acuity 
 
 of one eye 33 
 
 — in gradually increasing blind- 
 
 ness. . . .' 80 
 
 — in sudden blindness 89 
 
 — in damage to visual field 58 
 
 — in Aphakia 04 
 
 — in damage to muscles 65 
 
 P.\(iE. 
 
 Economic limitations of visual 
 
 acuity 33 
 
 — Improper estimate of Groe- 
 
 noiiw 20, 22 
 
 Economic limitations of visual 
 
 lield 43 
 
 Economic standard of visual 
 
 acuity 43 
 
 Elevator employes 37 
 
 Engineers 39, 40 
 
 Engineering, Profession of 36 
 
 Engine dispatchers 36 
 
 Estimation of distances and 
 
 shapes of objects 51 
 
 Expert evidence 13 
 
 Extrinsic ocular muscles 65 
 
 — Paralysis of 66 
 
 F. 
 
 Farmers 38 
 
 Fine mechanics 37 
 
 Firemen 37, 40 
 
 Flagmen 4t) 
 
 Foerster, Duty of physician 21 
 
 Food article manufacturers 40 
 
 Foreign bodies in eye 102 
 
 Fuchs '. 94 
 
 Fundamental principles for esti- 
 mation of effects of ocular 
 
 injuries 24 
 
 Freightmen, foremen, masters... 40 
 
 G. 
 
 Garment makers 37 
 
 Gas and water works employees. 37 
 
 Gatenien 40 
 
 German accident insurance law. 10, fO 
 
 — - Workmen and hospitals 16 
 
 German imperial insvu'ance of- 
 fice 35, 91 
 
 Glass-blowers 37 
 
 Golebiewski. Loss of one eye. ... 91 
 — Commentation on accident in- 
 surance law 91 
 
 Greenleaf, Evidence 13 
 
 Groenouw, Adjustment in con- 
 genital defects 31 
 
 Groenouw. Formula of 19 
 
 its intention 19 
 
 — - — has no general application. 20 
 
 is mathematicallv insolua- 
 
 ble ■ 21 
 
 in monocularism 21 
 
 nii.xes physiologic with ana- 
 tomic data 24
 
 INDEX. 
 
 141 
 
 PAGE. 
 
 — Xiiie-oyed monster 21 
 
 — Cyclops 21 
 
 — One-eyed person hypothetical- 
 
 ly earns nothing 20 
 
 Guards 39 
 
 Guillery, Accidents in one-eyed 
 
 persons 86 
 
 H. 
 
 Haab. Commoner affections of 
 the visual lield 
 
 — Normal limits of visual field.. 43 
 
 Hansen's estimates 105 
 
 Heddaeiis, Formula of 22 
 
 Hemianopsia 59, ()1, 63, 101 
 
 — Double sided 59 
 
 ■ — • Iraiimatic 59 
 
 Hyperopia conflicts with R. R. 
 
 service 40 
 
 Indemnity 11 
 
 — Relation of phvsician to 17 
 
 — To the one-eyed 14, 86, 90 
 
 — Reduction one year after acci- 
 
 dent 90 
 
 — Reduction of rates in recent 
 
 years ?0 
 
 Insurance, (see accident) 
 
 Intrinsic ocular musculature. . .44, 99 
 
 Iron and steel workers 37 
 
 Iron splinters, Injuries from. ... i 8 
 
 Injury of earning ability 11, CO 
 
 Iritis 100 
 
 J. 
 
 Jaeger's types plate II and 42 
 
 Jatzow, Indemnity to the one- 
 eyed ! 92 
 
 Josten, Economic Itmitations of 
 
 central visual acuity 34 
 
 — In military service 36 
 
 K. 
 
 Ivaufmann. Eye injuries 
 
 Knies. Loss of reading power in 
 
 right hemianopsia 50 
 
 Law. German accident (See acci- 
 dent) 16 
 
 Leather workers 37 
 
 Left eye and monocularism .... 92 
 Legal status of physician in 
 
 America 13 
 
 Lens, Injuries of 94 
 
 Lewis, Expert testimony 14 
 
 Light sense 30 
 
 Linen industry 37 
 
 Locomotive employees 39 
 
 Loss of binocular vision 32 
 
 Lids. Injuries of 98 
 
 — Inflammation of 100 
 
 Laboring classes 37 
 
 M. 
 
 Magnus. Numerous references... 
 
 Machinists and metal workers.. 37 
 
 Marine employees 37 
 
 Medico-legal experts (see expert 
 
 testimony) 13 
 
 Medical officers of comiianies. ... 13 
 ililitary standard of vision in 
 
 America 36 
 
 — Germany 36 
 
 ]\[edicine. Profession of 57 
 
 ]\[ill employees 37 
 
 Mine workers 38 
 
 -Monocular economic vision, for- 
 mula for 33 
 
 Monocular blindness. Danger of 
 
 total blindness in 92 
 
 — Ability to compete in 79, 87 
 
 — Definition of scientific 70 
 
 — -Definition of economic 70 
 
 — - Complaints in 93 
 
 — Acquired 85 
 
 — Congenital 86 
 
 — - Central visual acuity in 85 
 
 — Earning abilitv in acquired.. 88 
 
 — Visual field in* 85 
 
 — ilusculature in 86 
 
 — Sudden blinding of one eye.. 88 
 
 — Slowly increasing blindness cf 
 
 one eye 91 
 
 — Estimation of distances and 
 
 shapfs in 91 
 
 Moses. Indemnity to the one-eyed 92 
 
 — Loss of sight in workingmen. 
 Mooren, Muscular powers of one 
 
 eye 86 
 
 — Indemnity in acquired mo- 
 
 nocularism 91 
 
 — Opinion on the accident law. . 16
 
 142 
 
 IXDEX. 
 
 • I>A(iE. 
 
 — Loss of binocular vision .... lOi 
 Muscles of the eyes, ^Muscula- 
 ture ." . . 33, 4 1 
 
 — Intrinsic; 44, !.0 
 
 — Extrinsic in the fornuila 44 
 
 — Economic relations of 44 
 
 — Economic impoitanoe of dam- 
 
 age to 44 
 
 — Paralysis of (tables in part 
 
 IV.) 102, Go 
 
 — Damage to complicated with 
 
 damage to visual acuity 
 (tables in part IV.) 
 
 — Damage to complicated with 
 
 damage to visual field 
 (tables in part IV.) 
 
 — Damage to in acquired nio- 
 
 nocularism So 
 
 Musical instrument makers 37 
 
 X. 
 
 Xieden, Xystagmus of miners... 44 
 
 — Sight of the one-eyed 8U 
 
 Xine-eyed monster from Groe- 
 
 nouw's formula 21 
 
 Xoyes & Oliver 
 
 0. 
 
 Ocular muscles, (see muscles of 
 
 the eyes) 
 
 . Ocular injuries. Relation of, to 
 
 earning ability 30 
 
 Ocular earning aLilitv. Definition 
 
 of '. CO 
 
 One-eyedness, (see monocul ir 
 blindness) 
 
 Ottinger, Statistics of eye acci- 
 dents ' ' 91 
 
 Ordinate (see plates 1. and V.) .42, 52 
 
 One-eyed person sees nothing by 
 
 Groenoinv formula 21 
 
 P 
 
 Professional and business clauses 130 
 
 Pecuniary loss 104 
 
 Paper workers 37 
 
 Paper makers 37 
 
 Paraly.sis of extrinsic ocular 
 
 muscles OG 
 
 — intrinsic ocular muscles (ac- 
 commodation) 44, no 
 
 Pension Bureau. United States.. IG 
 Pensions, rente, indemnity for ac- 
 cidents . .' *. . .14, IG, 01 
 
 Peripheric vision (see visual field) 
 
 i'.v(;e. 
 
 Pliysician. Relation to accident 
 
 insurance — indemnity ...... 21 
 
 — Duty to deteimiiiie amciunt of 
 
 damage to earning ability.. 21 
 
 — Comes under class I., higher 
 
 visual demands 37 
 
 Porters 38 
 
 Pottery makers 37 
 
 Precious metal workers 37 
 
 Professions, higher, require higli- 
 
 er visual demands 37 
 
 Printers 37 
 
 Pupils 37 
 
 Q. 
 
 Quanymen 37 
 
 Quarles (see dedication and 
 preface) 
 
 R. 
 
 Railway employees 37 
 
 Railroads, German ministry of. 29, 41 
 
 Railway relief associations 40 
 
 Rectus muscles, relative economic 
 
 importance of 45, 32 
 
 Road foremen, masters 39 
 
 Rolling mill workers 37 
 
 — for Visual field 38 
 
 — for muscle 38 
 
 Root value for ability to compete 30 
 Relation of age to earning abil- 
 ity .3G, 104 
 
 Retina, Detachment of 101 
 
 Refraction, Errors of 102 
 
 S. 
 
 Schaflfner 
 
 Schloemilcli 
 
 Schmidt -Kimpler, Hemianopsia 
 
 dujilex traumatica 59 
 
 Sclunoeckel. Division of R. R. 
 
 employees into classes .... 39 
 Sehroeter,- Zones of the visual 
 
 field 43 
 
 — Economic valuation of limita- 
 
 tions of tlie visual field. ... 59 
 
 — Economic valuation in hemia- 
 
 nopsia ; 59 
 
 Scientitic standard of visual 
 acuity (transformed to eco- 
 nomic terms, plate I. and 
 
 table) 42 
 
 Signal men 39 
 
 Silex, Division of R. R. employ- 
 ees into classes 39 
 
 — -Limit of vision in R.R. s.rvice 39
 
 INDEX. 
 
 143 
 
 PAGE. 
 
 Sinkler. Rules of medical evidence 13 
 
 Silk industry 37 
 
 Snellen types (plate III.) 43 
 
 Soldiers and sailors 37 
 
 Street car (horse car) employees 38 
 
 Street car (motor) employees.. 37 
 
 Stephen 13 
 
 Station employees 39 
 
 Station baggagemen 39 
 
 Station agents 37 
 
 Statistics of one-eyed workmen . .23, 90 
 
 Stephen, Evidence 13 
 
 Sugar factory employees 38 
 
 Switchmen 39 
 
 Switchtenders 39 
 
 Symblepharon 96 
 
 Sympathetic ophthalmitis. Dan- 
 ger of 97 
 
 Sufficient visual acuity 39 
 
 Students ^-. 37 
 
 Tabulated values (part IV.) .... 
 
 Taylor, Evidence 13 
 
 — Law in relation to the physi- 
 cian 13 
 
 Teamsters 38 
 
 Telegraph operators 37 
 
 Textile industry 37 
 
 Thomson, Relative visual acuity 
 and color blindness, detec- 
 tion of 39 
 
 Tobacco workers 38 
 
 Track foremen 39 
 
 Three hypothetical eyes from Ze- 
 
 hender's formula 19 
 
 Theolog}", Profession of 37 
 
 Ti'ain baggagemen 39 
 
 Vision. Visual act factor of 32 
 
 — Physiologic 32 
 
 — Binocular 33 
 
 — - Economic 30 
 
 — Monocular 33 
 
 Visual Acuity. Gradual loss of.. 27 
 Visual Demands, Table for voca- 
 tions with higher (part IV.) 
 ■ 37, 42 
 
 — Table for vocations with lower 
 
 (part IV.) 37, 42 
 
 Vitreous opacities 102 
 
 Visual Acuity — 
 
 — Definition of 30 
 
 PAGE. 
 
 — Scientific meaning of 34 
 
 — Economic meaning of 34 
 
 — Transposition of scientific into 
 
 economic terms, plate I. and 
 table B 42 
 
 — Loss of 
 
 — Damage or injury to (tables I.- 
 
 II.. part IV.)'. . 
 
 — Damage of, in connection with 
 
 defects of visual field (tables 
 VII.-IX.) 66 
 
 — Damage or in connection with 
 
 defects of muscles 66 
 
 — In monocular blindness 73 
 
 — Modified 76 
 
 — Loss of in both eyes 30 
 
 — Economic limit of 33 
 
 — Sufficient limit of 35 
 
 \'isual Field, Binocular 43 
 
 — ^Monocular 72 
 
 — Economic limits of 43 
 
 — Economic valuation of damage 
 
 to binocular 43 
 
 — Economic valuation of damage 
 
 to monocular 72 
 
 — Slight limitation (see plate 
 
 IV.) 
 
 — ■Great limitation (see plate 
 
 IV.) 
 
 — Total loss of peripheric vision 58 
 
 — Limitation in one eye 58 
 
 — Partial defects in one field.. 58 
 
 — Partial defects in both fields. 58 
 — - Zones (plate IV.) 58 
 
 — Relative importance of. .... . 58 
 
 — Concentric contraction 58 
 
 — Disorders of. Complicated.... 62 
 
 — Damage or injury to (tables, 
 
 part IV.) '. 
 
 Von Woedtke, German accident 
 
 insurance law 16 
 
 W. 
 
 Wagner. Duty of physicians.... 21 
 
 Wagon masters 37 
 
 Walther, Examination of work- 
 
 ingmen's eyes 74 
 
 Warehousemen, keepers 38 
 
 W'atchmen 38 
 
 W^eak sight. Acquired in youth . . 34 
 
 W^eakness of vision 44 
 
 — Congenital 34 
 
 — Cleaning of, from economic 
 
 standpoint 74 
 
 Williams. Division of R. R. Em- 
 ployees into elapses 40
 
 144 
 
 INDEX. 
 
 PAGE. 
 
 Wipers 39 
 
 Wisconsin Eeports 13 
 
 Woodworkers and carpenters.... 37 
 
 Working ability, Definition of . . . 28 
 — not synonymous with earning 
 
 ability 28 
 
 Wiirdemann, Numerous references 
 
 Yardmen 37 
 
 PAGE. 
 
 Z. 
 
 Zehender. Formula of 18 
 
 • — Formula, Basis of his 18 
 
 — ^Mathematical value of 18 
 
 — The formula now only of his- 
 
 toric importance 19 
 
 — Examinations of workmen ... 75 
 
 — Three hypothetical eyes 19 
 
 — Lowest standard of visual 
 
 acuity 35 
 
 — Loss of one eye 92 
 
 — Danger of total blindness in 
 
 loss of one eye 92
 
 PLATES II AND IE. 
 
 Near and Distance Test Types.
 
 PLATE 11. 
 
 JAEGER'S TYPES WITH DISTANCES AT WHICH THEY MAY BE NORMALLY 
 
 SEEN AS RENDERED BY THE SCIENTIFIC AND 
 
 ECONOMIC STANDARDS. 
 
 FOR NEAR TEST OF THE VISUAL ACUITY. 
 
 Economic Standard for Lower Scientific Economic Standard for Higher 
 
 Visual Demands. Standard. Visual Demands. 
 
 0.3 0.6 0,45 
 
 Of the seventy=one conventions held here during the present year, thirty=two were 
 of national associations, and thirty^nine state. Since the annual meeting of a year ago 
 thirty^nine national conventions have been secured for Milwaukee through the agency 
 of the Citizens' Business League, three of which were for the present year and have al= 
 ready been held here, namely: American Society of Mechanical Engineers, United States 
 
 0.4 0.8 0.6 
 
 Weather Bureau Officials, and the American Banl<ers' Association. 
 For next year the list includes twenty=eight national and thirty=four 
 state conventions, and for the year following, we have already booked 
 eight national and ten state conventions. In addition to those already 
 
 0.5 1-0 0,75 
 
 secured, we are working with a number of im= 
 portant associations which we still hope to se= 
 cure for Milwaukee next year. Every time we 
 go after a convention, if we do not win out, we 
 
 0.75 1-5 1,2 
 
 enter a strong wedge to bring it here an= 
 other year. Among those we are hoping 
 to secure, selections having been referred 
 to executive committees, are the Traveling 
 
 \J^ 3.0 2.4 
 
 Freight Ag^ents' Associa= 
 tion of the United States, 
 the National Lumber Com
 
 PLATE III. 
 
 SNELLEN'S TYPES WITH DISTANCES AT WHICH THEY MAY NORMALLY 
 
 BE SEEN AS RENDERED BY THE SCIENTIFIC AND 
 
 ECONOMIC STANDARDS. 
 
 FOR DISTANT TEST OF THE VISUAL ACUITY. 
 
 Economic Standard for 
 
 Xower Visual Demands, 
 
 12 meters. 
 
 Scientific Standard, 
 24 meters. 
 
 Economic Standard for 
 
 Higher Visual Demands, 
 
 18 meters. 
 
 'St' 
 
 3 meters. 
 
 -tVi meters.
 
 PLATE IV. 
 
 The Visual Field.
 
 PLATE IV. 
 
 normal Binocular Uliual Tltld. 
 
 The yellow area is tli.- jiortioii lomraf.ii to both eyes; the red belo 
 to the left and the blue to the luoiiociilar field of the right eye 
 The heavy black circles divide the fields into three zoues of ec 
 economic importance. Chapter VI, § 13. 
 
 Co» of th( temporal nalcts or Botlt Ulsual Titlds 
 
 Valuation of the Remainder is -a nf the Normal. 
 Chapter IX, « Ifl. 
 
 Coss of the nasal fnAm of Both Ulsital TKIds. 
 
 A'ahiatiou of the Kemainder is I. 
 Chapter IX, Uil. 
 
 Coss of lilt nasal fialf of tht Ulsual f itld oi ihe Dii eyt. 
 
 Valuation of the Remainder is 1 . 
 Chapter IX, S l!l. 
 
 Coss of lite tomporal Half of ihe Ulsual TKid of iitt Rlflbi Eyt. 
 
 Valuation of the Kemainder is % . 
 Chapter IX, S 19. 
 
 Normal and Damaged Visual Fields with E,conomic Valuation.
 
 .Mrr. 
 
 PLATE V. 
 
 Curves for Valuation of the Visual Field, of the Muscular Action 
 and of the Ability to Compete.
 
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