Reliability of the electronic Early Treatment Diabetic Retinopathy Study testing protocol in children 7 to <13 years old

PURPOSE: To assess the test-retest reliability of the electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) visual acuity algorithm using the computerized Electronic Visual Acuity (EVA) tester in children 7 to <13 years old. DESIGN: Test-retest reliability study. METHODS: This multicenter study involved 245 subjects at four clinical sites. As the main outcome measure, visual acuity was measured twice using the E-ETDRS testing protocol on the EVA system, which uses a programmed handheld device to communicate with a personal computer and a 17-inch monitor at a 3-m test distance. RESULTS: Test-retest reliability was high (r = .94 for right eyes and 0.96 for left eyes) and for both right and left eyes, 89% of retest scores were within 0.1 logarithm of the minimal angle of resolution (logMAR) (five letters) of the initial test score and 99% of retests were within 0.2 logMAR (10 letters). Reliability was high across the age range of 7 to <13 years. Based on 95% confidence level estimates, a change in visual acuity of 0.2 logMAR (10 letters) from a previous acuity measure is unlikely to result from measurement variability. CONCLUSIONS: The E-ETDRS protocol using the EVA has high test-retest reliability in children 7 to <13 years of age. Potential advantages include better standardization across multiple sites, the ability to directly capture data electronically with an automatic acuity score calculation, the reduction of potential bias by limiting the tester's role, and the requirement of only a single testing distance for measurements from 20/800 to 20/12. This computerized testing method should be considered when visual acuity is used as an outcome measure in eye research involving children 7 to <13 years old.