For vision testing at 4 meters (13 ft.)
Acuity range 40M to 2M (20/200, 6/60 to 20/10, 63 equiv.)
Measures 62 X 65 cm (24.5 X 25.5 in.)
Eye chart fits ETDRS Illuminator Cabinet CAT. NO. 2425
Can also be wall-mounted
Printed on high-impact polystyrene
This "revised" ETDRS chart incorporates a slight change in difficulty score for each of the ten Sloan optotypes. These difficulty levels were derived from the best corrected visual acuity examinations of 7,420 eyes during the ETDRS study. The difficulty scores from the "original" charts were derived from the examination of 234 eyes. This further testing helped to pinpoint difficulty levels and further calibrate this already reliable test.
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