ETDRSstyle

ETDRSstyle is a term used to describe the standardized presentation and scoring conventions of the ETDRS visual acuity chart, a widely used instrument in ophthalmology for assessing distance vision. Developed for the Early Treatment Diabetic Retinopathy Study in the 1980s, the ETDRS chart is designed to provide reliable, comparable measurements across clinics and trials. A typical ETDRS-style chart uses five Sloan letters per line drawn from the Sloan set (C, D, H, K, N, O, R, S, V, Z), with letter sizes arranged in equal logMAR steps so that each line differs by 0.1 logMAR. The letters are presented with high contrast and fixed spacing, and the arrangement minimizes bias due to crowding or letter difficulty. In standard scoring, each correctly identified letter changes the logMAR score by 0.02, allowing precise acuity measurement across a wide range of vision.

ETDRSstyle practice emphasizes testing at a fixed distance, commonly four meters, under standardized lighting, with results reported in logMAR units. It is favored in many clinical trials and research studies for its improved test-retest reliability and comparability relative to Snellen charts. In digital or educational applications, ETDRSstyle may refer to software or templates that replicate these conventions to maintain consistency with traditional ETDRS testing.