For vision testing at 3 meters (10 ft.) Acuity range 30M to 1.5M (20/200, 6/60 to 20/10, 6/3 equiv.
Only standardized format accepted in studies sponsored by the National Eye Institute.
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.)
Eye chart fits the ETDRS Illuminator Cabinet CAT. NO. 2425
Can be wall-mounted
Original Series ETDRS chart calibrations were derived from the examinations and acuity results from 234 eyes. The study was sponsored by the National Eye Institute (NEI) and set a basis for all ETDRS acuity testing. ETDRS acuity charts have been tested, calibrated, accepted and ultimately designed for use in clinical studies and low vision evaluations were accurate and repeatable visual acuity measurements are required.
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