Distance of patient w hile reading Snellen chart is

(C) 6 meters # SNELLEN CHART is an eye chart that can be used to measure visual acuity.> Visual acuity = Distance at which test is made / distance at which the smallest optotype identified subtends an angle of 5 arcminutes.> In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres (or 20 ft). At this distance, the symbols on the line representing ""normal"" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the smallest line that a person with normal acuity can read at a distance of 6 metres (20 ft).