<prompt> Distance of patient w hile reading Snellen chart is6 feet25 ems6 meters25 feet  <response>: 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 66 or 2020, is the smallest line that a person with normal acuity can read at a distance of 6 metres 20 ft. 