Comparison of Visual Field Fluctuation Between Myopic and Emmetropic Glaucoma Patients

Background: Conflicting studies suggest that myopia may both increase and decrease the risk of developing glaucomatous visual field loss. To provide appropriate treatment, one must distinguish between visual field fluctuation, where variability occurs over days to weeks not due to pathological change, and true visual field progression. Objective: A retrospective, observational clinical study tests the hypothesis that myopic glaucoma patients demonstrate more long-term visual field fluctuation than emmetropic glaucoma patients. Methods: Four or more Humphrey visual field tests over several clinic visits were analyzed in 156 eyes. The visual field index (VFI) plot, mean deviation (MD), and threshold sensitivity on the glaucoma progression analysis were collected to quantify fluctuation. The sample had two groups: (1) emmetropic glaucoma eyes with a spherical equivalent refraction between +2 and -2 diopters and (2) high myopic glaucoma eyes with a spherical equivalent refraction ≤ -5 diopters. Two sample -tests and one-way analysis of variance (ANOVA) tests with random effect on subject using root mean square error of approximation (RMSEA) were used to compare fluctuation. Results: RMSEA two sample -tests between 78 myopic and 78 emmetropic glaucoma eyes found that myopic glaucoma eyes demonstrated significant fluctuation for MD (p = 0.006) and VFI (p = 0.035) compared with emmetropic eyes. Although myopic eyes showed greater fluctuation in MD (1.504 ± 1.016) and VFI (0.037 ± 0.045) compared with emmetropic glaucoma eyes (MD = 1.125 ± 0.652) (VFI = 0.026 ± 0.019), threshold sensitivity analyses did not reach statistically significant differences (p = 0.054) between myopic (1.609 ± 1.022) and emmetropic glaucoma eyes (1.339 ± 0.687). One-way ANOVA tests found statistically significant MD and VFI fluctuation difference (MD = -0.29, p value = 0.01) (VFI = -0.30, p value = 0.03) but not threshold sensitivity fluctuation difference = -0.19 (p value = 0.11). Conclusion: The results for MD and VFI, but not threshold sensitivity, are consistent with the hypothesis that myopic patients demonstrate more visual field fluctuation than emmetropic glaucoma patients.