Generating the Snellen Chart by computer

The Snellen Chart is the eye chart that is commonly used to measure visual acuity. The chart has combinations of nine different letters in eleven different lines, each smaller than the one above. Repeated measures of visual acuity may result in chart memorization and false information. Thus, a computer program was written to produce randomized multiple versions of Snellen eye charts. The chart may be changed at some distance from the computer in order to hear subject letter identifications during exercise testing. Different sized letters can also be produced so that the distance from the subject to the chart can vary.