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.
Can be wall-mounted.
ETDRS charts use a geometric progression from line to line, making only the optotype size a variable. Lines and optotypes have been calibrated to be equally difficult. ETDRS chart is reliable for accurate acuity testing in clinics, research, and studies world wide.