Sloan letters
Sloan letters, designed by Louise Sloan in 1959, are a set of optotypes used to test visual acuity generally used in Snellen charts and logMAR charts.
This set of optotypes consists of ten specially formed "letters", "C, D, H, K, N, O, R, S, V and Z"[1]. These optotypes are used because they differ from another optotype by 1 second of arc at a constant distance and size, so that all letters will be about as likely to be recognised.
Computer fonts for Macintosh and Windows operating systems are available for research purposes. The fonts are based on Louise Sloan’s design, which has been designated the US standard for acuity testing by the National Academy of Sciences, National Research Council, Committee on Vision (1980, Adv Ophthalmol, 41, 103-148). [2]
See also
References
- ↑ http://www.uniroma2.it/otticafp/va.html
- ↑ Pelli, Denis (2004-12-20). "Sloan font available". VSlist at NYU. Denis Pelli. Retrieved 2009-10-28.
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