key: cord-0735762-fy9n1yxx
authors: patil, Jayaprakash; patil, Laxmi; Parachuri, Nikulaa; Kumar, Nilesh; Bandello, Francesco; Kuppermann, Baruch D.; Loewenstein, Anat; Sharma, Ashish
title: Smartphone based ROP (S-ROP) screening—opportunities and challenges
date: 2020-04-28
journal: Eye (Lond)
DOI: 10.1038/s41433-020-0913-1
sha: 51e4745a3faf448a2c25908dedb71bb6ddfc47ce
doc_id: 735762
cord_uid: fy9n1yxx

nan

The greatest boon of the S-ROP screening has been its cost effectiveness. Policy makers would love the option of S-ROP screening given its low-cost, one-time investment, nil maintenance and repairs. With financial constraints in the lower and middle-income economies, any investment in ROP screening and imaging is considered an additional and un-called burden that could only serve a small population. In total, 3.5 million babies are born premature in India alone and the scale of the problem is much higher in the Sub-Saharan Africa [9] . Given the magnitude of ROP-related blindness in the developing world, any investment towards ROP screening should be considered imperative and of vital health-care importance. It is of general belief amongst the hospital management that the limited resources instead could be more efficiently utilised in other areas of ophthalmic practice that could subserve a larger population such as management of cataract blindness or due to DR and Glaucoma. S-ROP is the only feasible solution in terms of health economics at the moment for this problem. S-ROP screening also facilitates tele-ophthalmology with real-time transfer of images to a treating referral centre, thanks to the various apps that support these functions. Hence, S-ROP could be easily carried out in the peripheral units in remote and rural settings with a team of non-ophthalmic personnel such as technicians or nurses trained in image acquisition. There are no logistical barriers of moving a heavy, large piece of equipment by the screening team. The procedure is also considered to be less distressing for the baby as it is a non-contact procedure. This also minimises any risk of infection, as it does not involve any imaging probes. We have published a similar pilot model in the recent past [10] . Furthermore, it also allows for the imaging to be carried out in lower light exposure when compared with an indirect ophthalmoscope [11] .

The opportunities for future developments lie in the fact that S-ROP acquired images could easily be integrated with any AI algorithms and train the system to recognise and triage according to the stage of ROP with focussed machine-learning [5, 6] . This could potentially reduce the clinician's involvement at every stage of ROP management, making way for more efficient use of the trained paediatric ophthalmologists only when their expertise is inevitably needed.

The 3D printing technology has opened up options to develop custom-made retinal imaging adaptors for any smartphone or digital camera [7, 8] . Once developed, these adaptors last long and could be an indispensable resource in a non-institutional or solo practice, where financial strain could be a persistent limiting factor.

A low-cost, low-investment tool comes with its own limitations. The foremost challenge with S-ROP screening has been in obtaining high-quality images. The difficulty, although not directly related to the device, has largely been due to lack of experience and expertise in technical aspects of the image acquisition. Adequate, well-supervised training modules to improve the operator confidence in obtaining consistently good images in a short time frame could overcome this. The optimal placement of the condensing lens system, co-axial with the camera's field of view is a skill that needs mastering to obtain and reproduce excellent images.

Another issue that needs addressing is related to the width of imaging. The field of view with smartphone photography such as MII Ret Cam has been around 53°using a 28 D lens, this however, could be pushed up to 90°with the use of a 40 D lens [12] . ROP screening ideally requires imaging zones 2 and 3, both for diagnosis and monitoring the response to treatment. However, this cannot be a restraining factor per se, as the plus disease that determines the treatment could be ascertained with posterior pole visualisation and imaging which any of the S-ROP screening devices would facilitate [13] . Although the S-ROP screening models including Smart ROP initiative have managed to obtain satisfactory imaging, there is still a need to develop a better system to capture wide-field imaging (WFI). The width of imaging offered by the Retcam 2 is up to 130°and the Optos WFI, up to 200° [14, 15] .

Smartphone retinal photography is in its infancy but with advances in the field of imaging devices and smart phones, it is a tool that is here to stay. The opportunity that it could offer for lower-and middle-income countries is enormous despite its obvious limitations. The challenges it poses could in itself be an impetus for further developments and innovations. Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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