Abstract
Purpose:A new amblyopia tracker app has been designed to provide parents with a method of monitoring a child’s vision by presenting a single optotype size that the tester moves to identify the furthest distance the optotypes can be seen. The aim of this study is to evaluate this methodology in adults, comparing the findings to visual acuity (VA) measured with the iSight app and to determine the test retest variability.Methods:Adults, aged 18–39 years, with no known eye condition and VA ≤ 0.7 logMAR were recruited. Bangerter filters were used to simulate amblyopia, where VA was reduced below 0.0 with an interocular difference of at least 0.2 logMAR. Testing for both apps was performed monocularly, with the test order being randomised.Results:Data from 32 subjects were analysed. For the test retest variability analysis, paired t-tests showed no statistically significant difference between the tests for either eye, either app or the interocular acuity difference (p > 0.3 in all cases). Bland Altman plots showed similar limits of agreement between the two apps. When comparing measurements between the apps there was no statistically significant difference on the first or second test, either eye or the interocular acuity difference (p > 0.5 in all cases).Conclusion:The results support the theory that changing distance is a valid method of assessing VA as the measurements agree well with the standard approach of reducing optotype size. Test retest variability is similar between the two apps and there is good agreement between the measurements.
Highlights
Amblyopia affects the eyesight of 2–3% of children in the UK and Europe (Fu et al 2020; Hashemi et al 2018), requiring home treatment with occlusion or atropine and careful, regular monitoring of the child’s visual acuity (VA)
Four were excluded from the analysis as their VA on the iSight app was better than 0.0 logMAR, despite VA worse than 0.0 logMAR during the screening phase, leaving 32 participants in the analysis
One participant required no filters as their VA was within the required limits for the tracker app; four others only required a filter for one eye
Summary
Amblyopia affects the eyesight of 2–3% of children in the UK and Europe (Fu et al 2020; Hashemi et al 2018), requiring home treatment with occlusion or atropine and careful, regular monitoring of the child’s visual acuity (VA). Children undergoing amblyopia treatment require serial measurements of their VA to monitor any changes in response to treatment, which means that patients must attend for regular eye clinic appointments to monitor changes. During the COVID-19 pandemic these regular hospital appointments were postponed for many months, with guidance from the British and Irish Orthoptic Society to reduce occlusion time due to the lack of formal remote monitoring tools. The current guidance from the Royal College of Ophthalmologists in relation to paediatric ophthalmology (published 18 November 2020) states that ‘visual acuity apps do exist ..., but they are not fully validated against standard visual acuity tests’ (Royal College of Ophthalmologists 2020). Recent reviews have identified a lack of validation of tests for home use for virtual consultation telemedicine (Nagra et al 2020; Steren et al 2021)
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