Reichert ClearChart 4 User Manual

Reichert ClearChart 4 User Manual Manual pdf 23 page image

13795-101 Rev. F23OptotypesAll of the optotypes contained within the ClearChart 4 conform to the American National StandardInstitute guidelines for general purpose clinical visual acuity charts. The optotypes are constructed ona 5 x 5 matrix such that their stroke width is one-fifth of their overall size. Letter optotypes are of LetterGothic typeface.The spacing between optotypes of the same size is equal to the width of that size optotype. The spac-ing between rows of descending size is equal to the width of the larger optotype.The letters found in the seventeen letter set have been traditionally used in many visual acuity testingsituations. This letter set consists of these letters: A B C D E F G H K L N O P T U V Z.The eight letter set consists of these letters: C D E K N P U Z. The individual letters of this set havebeen shown to be equivalent to the Landolt ‘C’. Because of this, each letter is essentially equally leg-ible to patients. Unlike the seventeen letter set, no letter is easier or harder to identify than another.Since these letters can be presented in many combinations by the ClearChart 4, the few letters in theletter set do not pose a problem of memorization.ETDRS letters are the same as the Sloan letters, but are always displayed 5 per row (size permitting).The Sloan Letter Set consists of these letters: C D H K N O R S V Z.The tumbling ‘E’s and the Landolt ‘C’s are both presented in four positions: up, down, left, and right.The Children’s Shape Symbols are four shapes. As these symbolsbegin to blur, they are each perceived as circles.A second set of shapes for children consists of the following fiveshapes. These symbols may be more easily recognized and verbalizedby some children than the Children’s Shape Symbols.The Allen Symbols are only available up to size 100.Installation, Features, & Functions (continued)