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LogMAR-based visual acuity measurements: limits of normality


Catherine E. Stewart

Department of Optometry & Visual Science, City University, Northampton Square, London EC1V 0HP, GB
About Catherine E.

PhD BMedSci (Orthoptics)

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Aim: To review critically the literature on the use of logMAR visual acuity tests. This includes visual acuity norms for a range of different ages and tests, and repeatability values.

Method: A literature review was conducted of data on validity, age norms and repeatability of currently available logMAR tests.

Results: All the methodological discrepancies con­cerning the Snellen-based tests have been accounted for in the design of logMAR-based tests. Tests available for paediatric use include the crowded and uncrowded logMAR test, Kay’s linear logMAR crowded picture test. HOTV acuity test and the l ea Symbols chart. Normative acuity data have been reported for logMAR tests for children from 3 to II years of age and young adults. The data show that with increasing age the mean acuity improves and the range attributed to normal narrows. The repeatabil­ity and reliability of the ETDRS and crowded logMAR tests have been determined and values reported for the detection of change.

Conclusions: Research to date remains sparse on visual acuity norms as a function of age for log-based tests and data tend to be on one test for a limited age group. There is a need for comparative age-specific normative data for acuity scores for logMAR tests, which could only he achieved by undertaking a large cohort study evaluating multiple tests on the same children in the age range 3 to 7 years.
How to Cite: Stewart, C.E., 2006. LogMAR-based visual acuity measurements: limits of normality. British and Irish Orthoptic Journal, 3, pp.9–13. DOI:
Published on 01 Jan 2006.
Peer Reviewed


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