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.