Retinal Disease Caused by USH2A Mutations

Abstract

Purpose: : To increase understanding of the retinal micropathology and function in patients with mutations in USH2A.

Methods: : Patients with USH2A mutations (n=24, ages 17-66) were evaluated by ocular examination and kinetic perimetry. Retinal cross-sections, obtained by optical coherence tomography, were quantified along the horizontal meridian and related to co-localized visual thresholds by dark- and light-adapted static chromatic perimetry. Longitudinal data were obtained in many patients.

Results: : Visual acuity and kinetic visual field extent declined slowly over decades. Peripheral rod function could be measured into the 4^th decade of life. More than half of the patients had rod-mediated central islands and the age range was 17-47 years. Peripheral cone function could be near normal in many regions of the visual field and retained into the 5^th decade of life. All patients had measurable central cone function and, in about one-third of the cohort, this was within normal limits. Central retinal structure could be normal at early stages but structural integrity was eventually lost at increasing ages. Photoreceptor layer loss and features of inner retinal remodeling were present in retinal regions with severe visual dysfunction.

Conclusions: : USH2A patients showed a slow and definable time course of rod and cone disease. Retinal laminar abnormalities in regions of photoreceptor loss likely represent neuronal-glial remodeling.

Keywords: retinal degenerations: hereditary