Smartphone-Based Vision Test For Community-Based Evaluations

Andrew Bastawrous, MRCOphth International Centre for Eye Health, Clinical Research Department London School of Hygiene and Tropical Medicine (LSHTM), London, Interview with:
Andrew Bastawrous, MRCOphth
International Centre for Eye Health, Clinical Research Department
London School of Hygiene and Tropical Medicine (LSHTM), London, England

Medical Research: What is the background for this study? What are the main findings?

Dr. Bastawrous: As part of my PhD with the International Centre for Eye Health at the London School of Hygiene & Tropical Medicine, I led the follow-up of a major cohort study of eye disease [] following up 5,000 people in 100 different locations across the Great Rift Valley in Kenya. It was really challenging, two-thirds of the locations had no road access or electricity and we were carrying over £100,000 worth of fragile eye equipment and a team of 15 people in two vans to be able to carry out high quality measures of eye disease and answer some important questions for planning eye services.

What we found was that in the most difficult to reach locations we would find lots of people waiting to see us who had been unnecessarily blind from preventable/treatable diseases. Despite the locations having no roads, electricity and often no water, nearly all the locations had good phone signal.

Together with a brilliant team of developers, engineers and ophthalmologists we developed a suite of smartphone based tests to see if we could replace some of the standard equipment being used, in the hope that we could make it more portable and easier for non-specialists to perform so that ultimately the most high-risk individuals could be reached and treated.

This paper describes one of those tests, the visual acuity test – Peek Acuity.

Our field workers tested patients in their own homes using a standard card based Snellen chart (the type of vision test most non-ophthalmic healthcare workers are familiar with and has been the most commonly used acuity test for several decades now) and Peek Acuity. The same tests were repeated by the same healthcare worker in the clinic the following day as well as a reference standard vision test (LogMAR ETDRS) performed by an eye trained clinical officer.

This allowed us to perform “test re-test”, a measure of a tests repeatability. i.e. if you have the same test at two separate time points we would expect the the measures to be very close. We found that for both Peek Acuity and Snellen they were highly repeatable. An advantage of Snellen is the speed of the test, Peek Acuity came out slightly quicker overall. We also found when compared to the reference standard test, Peek Acuity was highly comparable and within a clinically acceptable limit of difference.

Dr. Bastawrous: What should clinicians and patients take away from your report?

Dr. Bastawrous: Vision testing is a crucial part of an ophthalmic examination and we demonstrated that it was possible to create a test that was independent of language (i.e. you don’t need to recognise English letters), it could be performed by non eye care workers, is more objective than standard vision tests as the examiner records the patients responses through gestures (swiping and shaking) without needing to know if the patient is giving the correct answer. The result is presented in the examiners preferred notation (LogMAR, Snellen metric or imperial) and we are able to the simulate the patients vision over a live video feed using SightSim(TM) to share the result in a more meaningful way.

However, a sight test alone, whichever way it is performed will not lead patients receiving eye treatment, if it is integrated in to a health system it can make up an important component of a visually impaired patient being identified. We are currently trialing systems that support automated referral and SMS reminders as well as incorporating other smartphone based tests (retinal and lens examinations, visual fields, colour and contrast).

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Future research should include using the test in different populations across different handsets in real world scenarios. We have recently completed a randomised control trial for a school screening program in Kenya where teachers screened over 20,000 children for visual impairment in schools. We hope to have the results of this later this year.

Peek Acuity will be freely available from the Google Play store once it has completed certification as a medical device (CE Class I) and will follow on iOS soon after. If you want to stay updated on releases please sign up to our newsletter at

Peek is a Portable Eye Examination Kit that uses smartphones to test eyes easily and affordably anywhere in the world. It has been developed through a collaboration between the London School of Hygiene & Tropical Medicine, the University of Strathclyde and the NHS Glasgow Centre for Ophthalmic Research.


Bastawrous A, Rono HK, Livingstone IT, et al. Development and Validation of a Smartphone-Based Visual Acuity Test (Peek Acuity) for Clinical Practice and Community-Based Fieldwork. JAMA Ophthalmol. Published online May 28, 2015. doi:10.1001/jamaophthalmol.2015.1468.

[wysija_form id=”3″] Interview with: Andrew Bastawrous, MRCOphth, International Centre for Eye Health, Clinical Research Department, & London School of Hygiene and Tropical Medicine (LSHTM), London, England (2015). Smartphone-Based Vision Test For Community-Based Evaluations

Last Updated on June 3, 2015 by Marie Benz MD FAAD