For testing at 2.5 meters (8.3 ft.)
Acuity range 25.2M to 1.2M (20/200, 6/60 to 20/10, 6/3 equiv.)
Only standardized format accepted in studies sponsored by the National Eye Institute.
Designed for use in clinical studies and low vision evaluations where accurate, repeatable visual acuity measurements are required.
Lines are of equal difficulty
Geometric progression in letter size from line to line
Letter size is only variable
Measures 62 X 65 cm (24.5 X 25.5 in.)
Chart fits the ETDRS Illuminator Cabinet CAT. NO. 2425
Can be wall-mounted
ETDRS Original Series visual acuity charts feature a constant difficulty score from the beginning of the acuity test until the end. Because each optotype and each line are equal in difficulty, the ETDRS test becomes more reliable and gives a patient a consistent test. "Lines gained or lost" can be accurately measured over time since the ETDRS chart features a consistent and reliable difficulty score.
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