Comparison of Microperimetry and Static Perimetry for Evaluating Macular Function and Progression in Retinitis Pigmentosa

Purpose To compare the usefulness of microperimetry (MP) and static automated perimetry (SAP) in retinitis pigmentosa (RP) patients, using macular anatomical metrics as a reference. Design Prospective, observational study. Participants Forty-eight eyes of 48 RP patients in Kyushu University Hospital who underwent MP-3 and Humphrey field analyzer (HFA) 10-2 testing at least 3 times during ≧ 2 years were included. Methods Macular anatomy (ellipsoid zone [EZ] length) was assessed by optical coherence tomography, and macular function was assessed by MP-3 (mean retinal sensitivity at radii 2°, 4° and 8°) and HFA10-2 program (mean retinal sensitivity at radii 2°, 4° and 8°). Correlations between functional and anatomical parameters were analyzed cross-sectionally at baseline and longitudinally by comparing the rate of progression. Main Outcome Measures Correlation coefficients between anatomical and functional metrics. Results The mean age at baseline was 50.1 ± 12.3 years, and the mean follow-up period was 2.8 ± 0.7 years. At baseline, EZ length was significantly correlated with MP-3 mean retinal sensitivity at radii 2°, 4° and 8° (Spearman’s ρ = 0.65, 0.84, 0.89; all P < 0.005) and HFA10-2 mean retinal sensitivity at radii 2°, 4° and 8° (Spearman’s ρ = 0.61, 0.73, 0.78; all P < 0.005). Longitudinal analysis showed that the slope of EZ length (-88.92 μm/year) was significantly correlated with the slope of MP-3 retinal sensitivity at 8° radius (-0.62 dB/year; Spearman’s ρ = 0.31, P = 0.03) and the slope of HFA retinal sensitivity at 8° radius (-0.60 dB/year; Spearman’s ρ = 0.43, P < 0.005). Conclusions Both MP-3 and HFA values were cross-sectionally well-correlated with EZ length in RP patients; however, these associations became weaker in the longitudinal analysis. This highlights the need for researchers to explore additional or more sensitive parameters to better monitor RP progression.