New design principles for visual acuity letter charts

Bailey, Ian L. & Lovie-Kitchin, Jan E. (1976) New design principles for visual acuity letter charts. American Journal of Optometry and Physiological Optics, 53(11), pp. 740-745.


This paper introduces new principles for the design and use of letter charts for the measurement of visual acuity. It is advocated that the test task should be essentially the same at each size level on the chart. Such standardization of the test task requires the use of letters of equal legibility, the same number of letters on each row, and uniform between-letter and between-row spacing. It is also advocated that, combined with the test task standardization, there should be a logarithmic progression of letter size. Charts incorporating these design features have been made. These charts facilitate the use of non-standard testing distances which might be used when there is low visual acuity, when examination room layout prevents testing at the standard distance, or when it is necessary to validate visual acuity scores or detect malingering. Adjusting the visual acuity score according to the chosen testing distance is simplified by the use of logarithmic scaling.

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730 citations in Web of Science®
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ID Code: 5724
Item Type: Journal Article
Refereed: Yes
Additional Information: For more information please refer to the publisher's website (link above) or contact the author:
Additional URLs:
ISSN: 0093-7002
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 1976 American Academy of Optometry
Deposited On: 01 Dec 2006 00:00
Last Modified: 15 Jan 2009 07:16

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