Adult Original Series ETDRS sloan letter vision chart 2 can be displayed in the illuminating light box with the chart having with proportionally spaced (geometric progression) lines; line sizes range from 20/200 to 20/10 (6/60 to 6/3) equivalent. Standardized format used in National Eye Institute clinical studies and in low vision evaluations that require accurate and repeatable visual acuity measurements. Chart measures 24.5" x 25.5" (62 cm x 65 cm)
13 feet, 4 meter testing distance