Eye chart test: This test measures how well you see at various distances. The eye chart itself -- the usual one is called 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.
Eye tests can determine your visual acuity; here's a sample eye chart and explanation of 20/20 vision.
Free eye charts to download! Classic Eye Chart: Joel Schneider's 3-page Snellen Chart plus near vision testing card. in PDF; PostScript source code. Modern Standard: ETDRS charts ...
Snellen Eye chart you can print out on your printer for home use to test your eyesight vision
Visual Accuracy Test The top of this eye chart should measure 5 inches across on your screen! Stand 10 feet from the screen (About 3 ...
How well can you see? Stand 20 feet away from this eye chart to test your vision.