Brian Hoyle

November 01, 2011

November 1, 2011 (Orlando, Florida) — A free and widely available Web-based test, developed and validated against conventional testing, allows parents to assess their children for amblyopia. The test provides a screening option for the most common cause of visual impairment in children.

"This layperson-administered Web-based test is valid for identifying amblyopia, making it possible for cost-effective and widely available vision screening to be performed by the lay public," the researchers, led by Shaival Shah, MD, from the Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, conclude in their poster here at the American Academy of Ophthalmology 2011 Annual Meeting.

The test was designed by David P. Taylor, who was a graduate student in the Department of Medical Informatics at the University of Utah, Salt Lake City, at the time, as a means of providing free access to amblyopia screening. Vision screening programs vary from state to state; in some states, vision is tested in only one quarter of children by the age of 5 years. assesses visual acuity, which has proven to be more reliable than other sensory tests.

In their study, 204 children (97 boys, 107 girls), 3 to 12 years of age (average age, 7.1 years), were prospectively tested by parents and by an ophthalmologist using the Electronic Visual Acuity (EVA) system. Participants were randomized according to which test was done first.

The online test comprises a series of 6 graphically rich, jargon-free, plain-language screens describing the test and how to interpret the findings. Typically, the test takes less than 15 minutes to complete.

Using the EVA system, 55 of the 204 study participants were considered to have amblyopia. Using the online test, 45 were considered to have amblyopia; 10 cases were missed. The sensitivity, specificity, positive predictive value, and negative predictive value of were 82%, 93%, 80%, and 93%, respectively. For a subset of kids 3 to 5 years of age, the sensitivity was 100% and the specificity was 87%.

In 53 of the 204 cases, the online test was done incorrectly — an error rate of 26%.

"We wanted to be honest and transparent in the reporting of the data, but the single most common error was that parents patched the incorrect eye — they mixed up their left and right. This happens all the time to beginning ophthalmology residents; for the purposes of vision screening, it is no big deal, as long as it's the opposite eye that is covered for the next part of testing. The next most common error was measuring the distance from the screen. Because not every home has 10 feet of space from the computer, we allowed measurements from 5 to 10 feet. In the study, we had a set distance from the screen that parents needed to measure from, and almost everybody did it correctly; those who did not were all within 1 foot," Dr. Shah told Medscape Medical News.

Refinements of the screen instructions might lead to fewer misinterpretations of the instructions and decrease the error rate, according to Richard Olson, MD, also from the University of Iowa, who was head of the research team.

"I have always been worried that a tool like this could, if used incorrectly, give false comfort and actually prevent someone from seeing a doctor when they otherwise would have — analogous to current concerns about the downsides of encouraging self-breast and testicle exams. This concern is what has kept me from promoting the use of this tool sooner and more widely. I believe it is a problem that can be solved; in fact, further testing of the tool may show that our error rate is artificially high and that the tool itself doesn't need to be changed," Dr. Olson explained to Medscape Medical News.

Other researchers have assessed the performance of the online test. "Replacing the traditional single optotype visual acuity test with would increase the efficiency and likely the sensitivity of amblyopia screening," notes Rosa Braga-Mele, MD, assistant professor, Department of Ophthalmology, University of Toronto, Ontario, Canada, in a recent paper (Can J Ophthalmol. 2010;45:368-374).

The study was funded by an unrestricted grant from Research to Prevent Blindness and the Doris Duke Charitable Foundation. Dr. Shah and Dr. Olson have disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2011 Annual Meeting: Abstract  PO167. Presented October 23, 2011.


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