Functional Vision in Patients With Biallelic USH2A Variants

To describe functional vision (FV) and investigate the relationship between FV, visual acuity (VA) and hill of vision (VTOT) at baseline in patients with bi-allelic USH2A variants.Multicenter, international, cross-sectional study Methods: In individuals with biallelic disease-causing variants in USH2A, Clinical diagnosis of Usher syndrome type 2 (USH2) or autosomal recessive non-syndromic retinitis pigmentosa (ARRP) was based on history of hearing loss and audiology exams. The VALVVFQ-48 was administered verbally to participants ≥18 years old. VA was measured in both eyes; VTOT was determined from static perimetry in the study eye (better VA). FV scores were calculated using Rasch analysis.Median age of 121 participants (76 with USH2, 45 with ARRP) was 41 years (range: 19 to 80); 54% were female. FV scores varied from -2.0 to 7.6 logits [median (interquartile range (IQR)): 2.8 (1.5-3.8)]. ARRP and USH2 participants had similar FV scores, both before [mean (95% CI): 2.8 (2.3-3.4) and 2.7 (2.3-3.2), respectively], and after [mean (95% CI): 2.5 (2.1-3.0) and 2.9 (2.6-3.3), respectively; P=0.24] adjusting for age, VA, disease duration, and VTOT. VA and VTOT accounted for 29% and 26% of variance in FV scores, respectively (P<0.001 for each). Together, they accounted for 36% of variance observed.Bi-allelic USH2A variants were associated with a large range of FV, yet similar in ARRP and USH2, despite hearing loss in USH2. The modified VALVVFQ-48 we evaluated is not ideal for detecting the impact of USH2A-associated retinal degenerations on activities of daily living.