Variability of Rarebit and Standard Perimetry Sizes I and III in Normals

Abstract

PURPOSE: To compare test-retest variability in rarebit perimetry (RBP) and conventional standard automated perimetry (SAP) using Goldmann size I and III stimuli. METHODS: Seventeen normal subjects underwent RBP, size I SAP, and size III SAP on five separate visits within a 5-week period. Test-retest variability could not be directly compared because of differences in units. Instead, data were transformed to lie on the same scale by calculating a percentile range to mean ratio for each test. RESULTS: Percentile range to mean ratio was highest for size I (3.42 ± 0.62), followed by size III (2.29 ± 0.55), and RBP (0.29 ± 0.10). Results for all three tests were significantly different from each other. CONCLUSIONS: Comparison of tests with different scales is problematic, but RBP's retest variability appears to be significantly less than both sizes I and III SAP in the measurement of normal subjects.