| Description | ETDRS charts use a series of three charts with different permutations of optotypes. ETDRS "Chart 1" is used to test the right eye's acuity. ETDRS "Chart 2," and "Chart R" are used to test the visual acuity in the left eye and both eyes, respectively | 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 | Similar to the "Original" Series ETDRS chart, this revised version features the use of three separate charts for the testing of each patient's eyes separately and together. Each of the three ETDRS charts feature a different configuration of | ETDRS "2000" Series charts utilize a geometric progression from line to line. Each optotype on the chart is proportionally spaced. By using these types of progression and spacing the chart becomes balanced and equal. This give the patient a well | ETDRS vision charts were used during the first phase of the Early Treatment Diabetic Retinopathy Study and Visual Acuity Impairment Study. The use of ETDRS eye charts in these studies have validated their use and has lead to them become the |