97th DOG Annual Meeting 1999
P646
VISUAL ACUITY ASSESSMENT USING LANDOLT OPTOTYPES, LEA SYMBOLS AND THE H-TEST, REPRODUCIBILITY OF VISUAL ACUITY ASSESSMENT WITH LANDOLT OPTOTYPES
R. Becker1, M. Gräf2, H. Kaufmann2
We compared the visual acuity measured with the Landolt C, Lea Symbols, and the H-test.
Patients and Methods: The right eye of 20 healthy subjects aged 18 to 25 years was examined by single Lea symbols (LSS, Precision Vision, USA), serial Lea symbols in close line (LSL), a Lighthouse Lea single symbol book (LH) and the H-test (HT) at a distance of 3m and with the single (LCS) and serial (17.2' and 2.6' interoptotype distance) Landolt C at a distance of 5m. Visual acuity assessment with the Landolt C 17.2' was repeated at the same day and several days later. The luminance of the test field was constant (180-200 cd/m2) and a 3 out of 4 criterion was used. Additionally, a 3 out of 5 criterion for the H-test (HT 3/5) was used.
Results: (mean values ± standard deviation) LSS 1.72 ± 0.9, LSL 1.57 ± 0.8, LH 1.58 ± 0.1, HT 1.58 ± 0.65, HT 3/5 1.62 ± 0.7, LCS 1.46 ± 0.6, LC 17.2' 1.43 ± 0.7, LC 2.6' 1.32 ± 1.1. Repetition of visual acuity assessment with the Landolt C 17.2' at the same day and several days later showed a standard deviation of ± 0.4 dB and ± 0.6 dB. The maximum difference was 1 dB. The difference between visual acuity measured with single Lea symbols (Precision Vision) and the Lighthouse Lea single symbol book was not significant.
Conclusion: There were little differences between the various optotypes. Visual acuity measured with Lea symbols and the H-test was higher than visual acuity determined with the Landolt C. The systematic differences have to be considered when changing from one test chart to another. Nevertheless, these optotypes are suitable for detection of strabismic amblyopia.
1 Universitäts-Augenklinik Giessen,
2 Universitäts-Augenklinik für Schielbehandlung und Neuroophthalmologie Giessen
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