Snellen's chart: The familiar eye chart used to measure how well you see at various distances.
Snellen's chart is imprinted with block letters that line-by-line decrease in size, corresponding to the distance at which that line of letters is normally visible.
The letters on Snellen's chart are, not surprisingly, called Snellen's test type. Each block letter is quite scientific in design (so that at the appropriate distance the letter subtends a visual angle of 5 degrees and each component part subtends an angle of 1 minute).
The chart and the letters are named for a 19th-century Dutch ophthalmologist Hermann Snellen (1834-1908) who came up with them as a test of visual acuity. Visual acuity refers to the clarity or clearness of the vision, a measure of how well a person sees. The word "acuity" comes from the Latin "acuitas" = sharpness.
The Snellen's Chart is a chart developed in 1862 by the Dutch ophthalmologist Herman Snellen, the son of the renowned physician, Dr. F. A. Snellen.
This is the same chart that your doctor uses to determine your visual acuity. The normal height for the letter A is 88 mm, and the viewing distance is 6 meters.
chart (chahrt) a record of data in graphic or tabular form. reading chart a chart printed in gradually increasing type sizes, used in testing acuity of near vision.
chart (chÃƒÂ¤rt) n. 1. A map showing coastlines, water depths, or other information of use to navigators. 2. An outline map on which specific information, such as ...
By Disabled World - 2007-10-30. Printable Snellen eye chart you can download and print for home use to determine your visual acuity ie. 20/20 vision.