Baseline Visual Field Findings in the RUSH2A Study: Associated Factors and Correlation with Other Measures of Disease Severity

PURPOSE: Baseline visual fields to monitor the Rate of Progression in USH2A-related Retinal Degeneration (RUSH2A) study. DESIGN: Cross-sectional study within a natural history study. SETTING: Multicenter, international STUDY POPULATION: Usher syndrome type 2 (USH2) (N=80) or autosomal recessive non-syndromic RP (ARRP) (N=47) associated with biallelic disease-causing sequence variants in USH2A. OBSERVATION PROCEDURES: Repeatability of full-field static perimetry (SP) and between-eye symmetry of kinetic perimetry (KP) were evaluated with intra-class correlation coefficients (ICC). The association of demographic and clinical characteristics with total hill of vision (VTOT) was assessed with general linear models. Associations between VTOT and other functional and morphologic measures were assessed using Spearman correlation coefficients and t-tests. MAIN OUTCOME MEASURES: VTOT (SP); III4e isopter area (KP). RESULTS: USH2 participants had more severe visual field loss than ARRP participants (P=.48; P<.05). Mean III4e isopter areas for left (4561±4426 deg2) and right eyes (4215±4300 deg2) were concordant (ICC=0.94). CONCLUSIONS: USH2 participants had more visual field loss than participants with USH2A-related ARRP, adjusting for duration of disease and age of enrollment. VTOT was repeatable and correlated with other functional and structural metrics, suggesting it may be a good summary measure of disease severity in patients with USH2A-related retinal degeneration