Retinal Sensitivity in KCNV2-Associated Retinopathy

The purpose of this study was to analyze the retinal sensitivity under photopic, mesopic, and scotopic conditions in a cohort of patients affected with KCNV2-associated retinopathy. Cross-sectional evaluation of molecularly confirmed individuals was conducted. Data were obtained prospectively. The main microperimetry parameters analyzed were mean sensitivity (MS) and number of floor effects (noF) in the central macular zone (CMZ; central 6 degrees) and peripheral macular zone (PMZ; 6 to 10 degrees). Interocular symmetry was also assessed. The MS under photopic, mesopic, and scotopic conditions were, respectively, 20.2 (6.3-29.5, ±6.5), 16.2 (3.7-23.1, ±5.3), and 1.3 (0-13.3, ±3.8) in the right eyes, and 21.1 (9.8-28.9, ±6.1), 16.8 (9.6-23.5, ±4.0), and 1.1 (0-12.4, ±3.5) in the left eyes. MS was highly symmetric between eyes (Pearson correlation coefficient) in photopic (r = 0.96, P < 0.0001), mesopic (r = 0.9, P < 0.0001), and scotopic (r = 0.98, P < 0.0001) testing conditions. MS was also highly symmetric (Pearson coefficient) in the photopic CMZ (r = 0.97, P = 0.0001) and PMZ (r = 0.95, P = 0.0002), mesopic CMZ (r = 0.94, P = 0.0003), and PMZ (r = 0.92, P = 0.0009), and scotopic CMZ (r = 0.99, P < 0.0001) and PMZ (r = 0.99, P < 0.0001).The mean noF (± standard deviation [SD]; range) was 4.6 (SD = ±5.3, range = 0-16) in photopic, 5.0 (SD = ±5.4, range = 0-15) in mesopic, and 23.2 (SD = ±8.6, range = 0-28) in scotopic conditions. Subject 01-041 was the only affected individual in which no floor effect was found. Simple linear regression revealed a significant inverse relationship between age and MS, and a direct relationship between age and noF. KCNV2-associated retinopathy is a largely symmetric disease from a functional perspective. Despite the early decrease in scotopic retinal sensitivity, our data suggests a large window for photoreceptor rescue with novel treatments, such as gene therapy.