A computerized method of visual acuity testing: Adaptation of the early treatment of diabetic retinopathy study testing protocol

Roy W. Beck, Pamela S. Moke, Andrew H. Turpin, Frederick L. Ferris, John Paul SanGiovanni, Chris A. Johnson, Eileen E. Birch, Danielle L. Chandler, Terry A. Cox, R. Clifford Blair, Raymond T. Kraker

Research output: Contribution to journalArticlepeer-review

394 Scopus citations

Abstract

PURPOSE: To develop a computerized method of visual acuity testing for clinical research as an alternative to the standard Early Treatment for Diabetic Retinopathy Study (ETDRS) testing protocol, and to evaluate its test-retest reliability and concordance with standard ETDRS testing. DESIGN: Test-retest reliability study. METHODS: Multicenter setting of a study population of 265 patients at three clinical sites. Visual acuity was measured with both the electronic visual acuity testing algorithm (E-ETDRS) and standard ETDRS protocol (S-ETDRS) twice on one eye of each patient. E-ETDRS testing was conducted using the electronic visual acuity tester (EVA), which utilizes a programmed Palm (Palm, Inc, Santa Clara, California, USA) hand-held device communicating with a personal computer and 17-inch monitor at a test distance of 3 meters. RESULTS: For the E-ETDRS protocol, test-retest reliability was high (r = 0.99; with 89% and 98% of retests within 0.1 logMAR and 0.2 logMAR of initial tests, respectively) and comparable with that of S-ETDRS testing (r = 0.99; with 87% and 98% of retests within 0.1 logMAR and 0.2 logMAR of initial test, respectively). The E-ETDRS and S-ETDRS scores were highly correlated (r = 0.96 for initial tests and r = 0.97 for repeat tests). Based on estimates of 95% confidence intervals, a change in visual acuity of 0.2 logMAR (10 letters) from a baseline level is unlikely to be related to measurement variability using either the E-ETDRS or the S-ETDRS visual acuity testing protocol. CONCLUSIONS: The E-ETDRS protocol has high test-retest reliability and good concordance with S-ETDRS testing. The computerized method has advantages over the S-ETDRS testing in electronically capturing the data for each tested letter, requiring only a single distance for testing from 20/12 to 20/800, potentially reducing testing time, and potentially decreasing technician-related bias.

Original languageEnglish (US)
Pages (from-to)194-205
Number of pages12
JournalAmerican Journal of Ophthalmology
Volume135
Issue number2
DOIs
StatePublished - Feb 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology

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