Wolfgang Wesemann1. 1. Höhere Fachschule für Augenoptik Köln, Germany. wesemann@hfak.de
Abstract
INTRODUCTION: If different ways for correcting refractive errors of the human eye have to be compared, accurate and reproducible measurement procedures are necessary. METHODS: Binocular visual acuity of 130 students without pathologies was measured with the Freiburg Visual Acuity Test, the Bailey-Lovie chart and a Landolt ring chart (4 orientations). The reproducibility of the FVT was determined by repeated measurements. RESULTS: The average visual acuity was 1.93 +/- 0.03 (= 20/10.4) with the FVT, 1.82 +/- 0.03 (= 20/11) with the Landolt ring chart, and 1.48 +/- 0.02 (= 20/13.5) with the Bailey-Lovie chart. 50 % of all repeated measurements with the FVT were within an interval of +/- 0.035 logMAR from the mean value. 95 % were within +/- 0.1 logMAR. Results of earlier studies are discussed. CONCLUSION: On average, visual acuity values found with the Freiburg Visual Acuity Test were slightly larger as compared to the Landolt ring chart (difference = 0.025 logMAR). Taking the maximal difference of 0.05 logMAR tolerated by the international standard DIN EN ISO 8597 into account, both tests are equivalent. The results found with the Bailey-Lovie chart were substantially lower as compared to the Landolt ring chart (difference = 0.09 logMAR). The Freiburg Visual Acuity Test has a high reproducibility and measures visual acuity on a continuous scale that is not limited to the traditional visual acuity steps. Thus, it can be recommended as a reference procedure for comparative visual acuity studies.
INTRODUCTION: If different ways for correcting refractive errors of the human eye have to be compared, accurate and reproducible measurement procedures are necessary. METHODS: Binocular visual acuity of 130 students without pathologies was measured with the Freiburg Visual Acuity Test, the Bailey-Lovie chart and a Landolt ring chart (4 orientations). The reproducibility of the FVT was determined by repeated measurements. RESULTS: The average visual acuity was 1.93 +/- 0.03 (= 20/10.4) with the FVT, 1.82 +/- 0.03 (= 20/11) with the Landolt ring chart, and 1.48 +/- 0.02 (= 20/13.5) with the Bailey-Lovie chart. 50 % of all repeated measurements with the FVT were within an interval of +/- 0.035 logMAR from the mean value. 95 % were within +/- 0.1 logMAR. Results of earlier studies are discussed. CONCLUSION: On average, visual acuity values found with the Freiburg Visual Acuity Test were slightly larger as compared to the Landolt ring chart (difference = 0.025 logMAR). Taking the maximal difference of 0.05 logMAR tolerated by the international standard DIN EN ISO 8597 into account, both tests are equivalent. The results found with the Bailey-Lovie chart were substantially lower as compared to the Landolt ring chart (difference = 0.09 logMAR). The Freiburg Visual Acuity Test has a high reproducibility and measures visual acuity on a continuous scale that is not limited to the traditional visual acuity steps. Thus, it can be recommended as a reference procedure for comparative visual acuity studies.
Authors: Herbert Jägle; Emanuela de Luca; Ludwig Serey; Michael Bach; Lindsay T Sharpe Journal: Graefes Arch Clin Exp Ophthalmol Date: 2005-08-23 Impact factor: 3.117