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Smartphone Vision App Found Accurate as Clinic Test

Visual acuity test on smartphone

Visual acuity test on smartphone (

29 May 2015. An inexpensive smartphone-based test was found to measure visual acuity as well as the familiar standard eye chart used in clinics. The team that developed the Portable Eye Examination Kit or Peek at the London School of Hygiene and Tropical Medicine and other institutions in the U.K. published its results in yesterday’s issue of the journal JAMA Ophthalmology.

Visual impairment is a global health issue, and one likely to to increase as lifespans increase along with numbers of older people. A 2010 review of surveys in 39 countries estimates some 285 million people worldwide have some form of impaired vision, mainly uncorrected refractive (focusing) errors and cataracts.

The Peek research team — including members from University of Strathclyde and National Health Service Glasgow Centre for Ophthalmic Research in Scotland — were seeking a way to make visual acuity tests more widely available, particularly in low-resource countries. The standard visual acuity test — the familiar Snellen eye chart — dates back to the 1860s and is viewed from a distance of 20 feet (6 meters), usually requiring an office or clinic.

The researchers, led by Andrew Bastawrous, a lecturer at the London School, designed their solution for use in the home, with ubiquitous smartphones as the basic technology, yet still needed to be accurate and reliable enough to substitute for testing in the clinic. The result is Peek, a series of smartphone apps and a hardware attachment that views the retina and conducts a number of tests for visual impairment, including cataracts and glaucoma. A crowdfunding campaign for Peek’s development closed earlier this month on Indiegogo, raising £130,475 ($US 200,000), 57 percent more than its goal.

In the journal article Bastawrous and colleagues tested Peek’s test for visual acuity among older adults in central Kenya. The team recruited 233 participants, age 55 and older, from 300 invitees, who were tested for visual acuity first in their homes with Peek, then the next day in the clinic. In both cases, the standard Snellen chart is adapted to show the iconic capital E pointing in different directions, called “tumbling E”, for regions where the Roman alphabet is not used. The participant indicates the direction the E is pointing as the image gets smaller, either on the standard chart or on the smartphone.

The results show visual acuity tests with Peek are comparable to Snellen chart tests, and comparable as well with reference visual acuity measurements that also use the tumbling E. In addition, the average time needed to test with Peek (77 seconds) is comparable to Snellen charts (82 seconds), and required minimal training for the Kenyan staff to administer.

The authors acknowledge the sample of older Kenyans in the study is hardly representative of any larger populations, and plan more testing among more diverse participants, including children. The research team used an Android smartphone for the study, and intend to extend the technology to other mobile platforms.

Bastawrous and associates tell more about Peek in this video prepared for the now-completed Indiegogo campaign.

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