Peek, a smartphone-based app for testing eyesight is as accurate as traditional eye charts, according to a study published today.

The app, named Peek (for Portable Eye Examination Kit) is a system for complete visual acuity testing anywhere. It was designed and developed by scientists at University of Strathclyde, London School of Hygiene & Tropical Medicine, and the NHS Glasgow Centre for Ophthalmic Research.

By empowering health workers to test eyes easily and affordably in the community, Peek offers a solution to the growing problem of visual impairment in low-income countries.

285 million people worldwide are estimated to be visually impaired. 80% of them have diseases which could be cured or prevented.

Most Have Limited Access To Specialist Clinics

Results from tests carried out on 233 people in their own homes using the app, and repeated in eye clinics based in Kenya, were as reliable as those from the standard paper-based eye charts and illuminated vision boxes used in an eye clinic.

Peek’s vision test was designed so that patients do not need to be familiar with symbols or letters used in English.

THe idea came from the paper’s lead author Dr Andrew Bastawrous, lecturer in International Eye Health at the London School of Hygiene & Tropical Medicine. He was try to cope with transporting bulky eye equipment to remote areas in Kenya.

He decided to try to create a future replacement for the unweildy equipment using a phone-based testing system during a six-year follow-up of the Nakuru Eye Disease Cohort:

“With most of the world’s blind people living in low-income countries, it is vital we develop new tools to increase early detection and appropriate referral for treatment. Mobile phone use is now so widespread that it seemed to be an ideal platform.

In this study we aimed to develop and validate a smartphone-based visual acuity test for eyesight which would work in challenging circumstances, such as rural Africa, but also provide reliable enough results to use in routine clinical practice in well-established healthcare systems.

Our ultimate hope is that the accuracy and easy to use features of Peek will lead to more people receiving timely and appropriate treatment and be given the chance to see clearly again."

Peek Acuity

Peek is composed of a series of apps, in combination with the Peek Retina, a novel piece of hardware.

The current study focused on one of the apps, called Peek Acuity. It which determines how clearly an individual sees.

Acuity displays a “tumbling E” on the screen, featuring the letter E displayed in 1 of 4 orientations.

The patient points in the direction they see the arms of the E pointing. Then the tester uses the touch screen to swipe accordingly, translating the gestures from the patient to the phone.

Tests using Peek Acuity at a distance of 2m and a reduced 3m “tumbling E” Snellen chart were carried out in the participant’s home and in the central clinic on two consecutive days.

Average testing time was also measured and found that the familiar and commonly used Snellen test took 82 seconds compared with 77 seconds for Peek Acuity which shows that using Peek is as quick to use as traditional methods.

The researchers are doing other studies to check the suitability of the tool in different contexts. Testing is planned across a variety of different handsets and operating systems, and will include a trial involving teachers testing over 20,000 schoolchildren.


Andrew Bastawrous, MRCOphth; Hillary K. Rono, MBBS; Iain A. T. Livingstone, FRCOphth; Helen A. Weiss, PhD; Stewart Jordan, BSc; Hannah Kuper, ScD; Matthew J. Burton, PhD Development and Validation of a Smartphone-Based Visual Acuity Test (Peek Acuity) for Clinical Practice and Community-Based Fieldwork AMA Ophthalmol.  doi:10.1001/jamaophthalmol.2015.1468

Photo: Jhong Dizon/flickr

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