Natural History of Retinal Function and Structure in a French Cohort of Patients with Usher Syndrome

Abstract

Purpose : The purpose of this study is to describe and compare the visual impairment and disease progression in patients with Usher Syndrome (USH) types USH1 and USH2 caused by MYO7A and USH2A mutations respectively.

Methods : Retrospective cohort study of USH patients followed at the National Eye Hospital CHNO des Quinze-Vingts. Two years follow up data from 16 USH1B and 27 USH2A patients were collected. Evaluation included visual acuity (VA: total number of letters read on ETDRS charts ), color vision (CV), macular sensitivity (MS), Goldmann visual field (VF), fundus autofluorescence retinal imaging (FAF) and SD OCT. For baseline characteristics and their changes over the first 2 years we computed means ± SD or percentages for all eyes according to age (<20, 20-40, >=40) and genetics. Changes from baseline in VA were assessed using Wilcoxon test and χ² test for comparisons. Intra-Class Correlation coefficient and Cohen's kappa were used to assess between/within person eye-differences.
chart or charts???

Results : Mean age was 34.75 years in USH1B group and 41.6 years in USH2A group, with only one patient <20 years old in USH2A. The characteristics of both eyes were similar in each patient. In age class 20-40, the functional parameters were greater in USH2A (VA = 74.7±9 vs 64.0±13.2 in USH1B), CV altered in 55% vs 60% in USH1B, III4 horizontal binocular visual field Diameter (HBFV) = 50°±45 vs 27°±18 in USH1B). Similar differences were observed in age class > 40, with lower values for all the parameters (VA = 49.1±26.6 vs 40.8±26.6, CV altered in 100% in both groups, HBVF = 52°±55 vs 15°±11). Mean changes from baseline to visit "2 years" in each age class and group were limited and variable for the functional parameters, but OCT ISOS length decreased significantly. The loss of ISOS was similar in both groups (141µm±149 in USH2A vs 222 µm±183 in USH1B).

Conclusions : The results are consistent with more severe retinal disease in USH1 patients compared to USH2 patients. The subjectivity and variability of the functional markers made difficult the assessment of changes over time. On the contrary, the decrease in the ISOS lengths over the period of 2 years supports anatomical measurements as potential markers for short-term disease progression.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.