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.
Can be wall-mounted.
ETDRS chart features equivalents listed on both the right and left sides of the acuity chart. These equivalents include feet, meters, decimal, and LogMar. This ETDRS acuity test is calibrated for testing at 4 meters. However, acuity results can be converted to several different equivalents easily.