Static Perimetry in the Rate of Progression in USH2A-related Retinal Degeneration (RUSH2A) Study: Assessment Through...

To evaluate disease progression using static perimetry (SP) in patients with USH2A-related retinal degeneration, including Usher syndrome type 2 (USH2) and nonsyndromic autosomal recessive retinitis pigmentosa.

Prospective, observational cohort study.

A total of 102 patients with biallelic disease-causing sequence variants in USH2A with baseline best-corrected visual acuity (BCVA) letter score ≥54 were recruited from 16 clinical sites in Europe and North America. SP, BCVA, full-field stimulus thresholds, spectral domain optical coherence tomography macular scans, and fundus-guided mesopic microperimetry were performed at baseline and annually. The main outcome measures were total hill of vision (V_TOT), hill of vision in the central 30° (V₃₀), V_TOT minus V₃₀ (V_PERIPH), and mean sensitivity.

The average decline (95% CI) was 2.05 (1.40, 2.70) decibel-steradian (dB-sr)/y for V_TOT, 0.48 (0.32, 0.65) dB-sr/y for V₃₀, 1.53 (0.97, 2.08) dB-sr/y for V_PERIPH, and 0.55 (0.40, 0.71) dB/y for mean sensitivity. Average percentage decline per year was 8.3 (5.5, 11.1) for V_TOT, 5.2 (3.0, 7.4) for V₃₀, 16.0 (9.5, 22.0) for V_PERIPH, and 5.1 (3.5, 6.7) for mean sensitivity. Changes from baseline to year 2 in all SP measures were highly correlated (r's ranging from 0.52 [V₃₀ vs V_PERIPH] to 0.98 [V_TOT vs V_PERIPH]).

Quantitative measures of SP declined significantly over 2 years in USH2A-related retinal degeneration. The annual percentage rate of change was greatest for V_TOT and V_PERIPH, whereas V₃₀ and mean sensitivity changed least, reflecting earlier and more severe peripheral degeneration compared with central loss.