Purchase this article with an account.
Kavitha Ratnam, Hanna Vastinsalo, Sanna Sundquist, Austin Roorda, Eeva-Marja K. Sankila, Jacque L. Duncan; Cone Structure in Patients with Usher Syndrome III Caused by Mutations in the Clarin-1 Gene. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4975.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To study macular structure and function in patients with Usher syndrome type III (USH3A) caused by mutations in the clarin-1 (CLRN1) gene.
High-resolution macular images were obtained with Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography (SDOCT) in 2 patients with USH3A and compared with data from 20 normal subjects. Visual function measures included best-corrected visual acuity (BCVA), kinetic and static perimetry, and full-field electroretinography (ffERG). Mutation analysis of the CLRN1 gene was carried out by sequencing the coding regions.
Molecular analysis revealed compound heterozygous mutations (p.N48K and p.S188X, a novel C>A change at nucleotide position c.563 which results in an early termination signal at codon 188) in an 18-year-old man, and homozygous mutations (p.N48K) in a 24-year-old woman in the CLRN1 gene. Each patient had excellent BCVA (20/20) and scotomas beginning between 10 degrees (deg) from fixation. FfERG in both patients showed severe outer retinal dysfunction affecting rods to a greater extent than cones. Both patients showed gradual thinning of the outer segment layer and disruption of the inner segment-outer segment (IS-OS) junction beginning 5 deg from fixation. Cones within 4 deg of the fovea had normal density and reflectance, but the central preserved region ended discretely and peripheral photoreceptor degeneration precluded accurate cone-spacing measures.
Central retinal structure and function were preserved in 2 patients with USH3A caused by mutations in the CLRN1 gene. AOSLO revealed cones where the photoreceptor IS-OS junction was intact, but unambiguous cones were not seen and the IS-OS junction was disrupted in regions corresponding to scotomas, consistent with cone loss. High-resolution images of retinal structure correlated with retinal function in patients with CLRN1 mutations.
This PDF is available to Subscribers Only