Static Perimetry in the Rate of Progression in USH2A-related Retinal Degeneration (RUSH2A) Study: Assessment Through 2 Years.

PURPOSE

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.

DESIGN

Prospective, observational cohort study.

METHODS

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), hill of vision in the central 30° (V), V minus V (V), and mean sensitivity.

RESULTS

The average decline (95% CI) was 2.05 (1.40, 2.70) decibel-steradian (dB-sr)/y for V, 0.48 (0.32, 0.65) dB-sr/y for V, 1.53 (0.97, 2.08) dB-sr/y for V, 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, 5.2 (3.0, 7.4) for V, 16.0 (9.5, 22.0) for V, 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 [V vs V] to 0.98 [V vs V]).

CONCLUSIONS

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