Reliability of Three Different Visual Acuity Testing Procedures in School Children

Abstract

Aim To evaluate the usability and reliability of three different visual acuity (VA) testing procedures using Landolt C's in 8 positions with a semi-automated computer program in school children. Methods 100 school children (median 7 years, 59 boys and 41 girls) were included; only the better eye was tested. We used the semi-automated computer program CORVIS®.VT in a forced choice method. Three different test strategies were employed, each two times: A) DIN, B) Standard-Staircase and C) Best-PEST procedure with sequences A, B, C or A, C, B. Results Average testing time was 100s ± 45 (DIN), 59s ± 36 (Staircase) and 77s ± 25 (Best-PEST). The mean VA estimated with DIN was equivalent to that with the Best-PEST procedure. However, the mean VA with Standard-Staircase was one line less. In DIN, 76% of the retest scores were within 0.1 logMAR unit of the initial test score (Staircase: 72%, Best-PEST 73%). The 95% confidence interval of test-retest reliability was calculated to be −0.05 ± 0.24 logMAR in DIN, +0.02 ± 0.32 logMAR in Staircase, and 0.00 ± 0.29 logMAR in Best-PEST. Conclusion A high percentage of children aged 6 to 9 years (98%) can be tested with Landolt C's (8 positions). We found a decreasing test-retest reliability starting from DIN via Best-PEST to Staircase in this configuration.

KEYWORDS:

• Visual acuity testing
• school children
• computer program
• Landolt ring
• test-retest reliability