A Arditi1, R Cagenello. 1. Vision Research Laboratory, Lighthouse Inc., New York, New York 10017.
Abstract
PURPOSE: To determine boundary values of test-retest reliability and sensitivity to acuity change that are unlikely to be exceeded in any clinical situation, for a popular visual acuity chart (Lighthouse/ETDRS) with three scoring methods; to discuss general methodological issues associated with statistical accuracy of optotype chart testing; and to link measures of test reliability to measures of sensitivity to change. METHODS: Five highly practiced subjects were tested using a computer-controlled acuity testing system in a procedure designed to reduce measurement error. Subjects read the computerized chart 156 times, yielding a sample of 78 test-retest comparisons. RESULTS: Under conditions likely to minimize variability, visual acuity may, with 95% confidence, be ascertained only within +/- 0.1 log units, using this chart with the recommended letter-by-letter scoring. Detecting a significant change in visual acuity requires about +/- 0.14 log units for the same degree of confidence. CONCLUSIONS: These measurements may be viewed as approaching the upper limit of reliability of this letter chart. Reliability probably is considerably less in typical usage.
PURPOSE: To determine boundary values of test-retest reliability and sensitivity to acuity change that are unlikely to be exceeded in any clinical situation, for a popular visual acuity chart (Lighthouse/ETDRS) with three scoring methods; to discuss general methodological issues associated with statistical accuracy of optotype chart testing; and to link measures of test reliability to measures of sensitivity to change. METHODS: Five highly practiced subjects were tested using a computer-controlled acuity testing system in a procedure designed to reduce measurement error. Subjects read the computerized chart 156 times, yielding a sample of 78 test-retest comparisons. RESULTS: Under conditions likely to minimize variability, visual acuity may, with 95% confidence, be ascertained only within +/- 0.1 log units, using this chart with the recommended letter-by-letter scoring. Detecting a significant change in visual acuity requires about +/- 0.14 log units for the same degree of confidence. CONCLUSIONS: These measurements may be viewed as approaching the upper limit of reliability of this letter chart. Reliability probably is considerably less in typical usage.
Authors: L J van Rijn; H Wilhelm; M Emesz; R Kaper; S Heine; S Nitsch; G Grabner; H J Völker-Dieben Journal: Br J Ophthalmol Date: 2002-11 Impact factor: 4.638
Authors: L J van Rijn; C Nischler; D Gamer; L Franssen; G de Wit; R Kaper; D Vonhoff; G Grabner; H Wilhelm; H J Völker-Dieben; T J T P van den Berg Journal: Br J Ophthalmol Date: 2005-03 Impact factor: 4.638