Normal Central Retinal Function and Structure Preserved in Retinitis Pigmentosa
ABSTRACT To determine whether normal function and structure, as recently found in forms of Usher syndrome, also occur in a population of patients with nonsyndromic retinitis pigmentosa (RP).
Patients with simplex, multiplex, or autosomal recessive RP (n = 238; ages 9-82 years) were studied with static chromatic perimetry. A subset was evaluated with optical coherence tomography (OCT). Co-localized visual sensitivity and photoreceptor nuclear layer thickness were measured across the central retina to establish the relationship of function and structure. Comparisons were made to patients with Usher syndrome (n = 83, ages 10-69 years).
Cross-sectional psychophysical data identified patients with RP who had normal rod- and cone-mediated function in the central retina. There were two other patterns with greater dysfunction, and longitudinal data confirmed that progression can occur from normal rod and cone function to cone-only central islands. The retinal extent of normal laminar architecture by OCT corresponded to the extent of normal visual function in patients with RP. Central retinal preservation of normal function and structure did not show a relationship with age or retained peripheral function. Usher syndrome results were like those in nonsyndromic RP.
Regional disease variation is a well-known finding in RP. Unexpected was the observation that patients with presumed recessive RP can have regions with functionally and structurally normal retina. Such patients will require special consideration in future clinical trials of either focal or systemic treatment. Whether there is a common molecular mechanism shared by forms of RP with normal regions of retina warrants further study.
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ABSTRACT: PURPOSE: To evaluate the role of CRB1 (crumbs homolog 1) in autosomal recessive (AR) retinal diseases in the Israeli and Palestinian populations using homozygosity mapping. METHODS: Clinical analysis included family history, ocular examination, full-field electroretinography (ERG), and funduscopy. Molecular analysis included homozygosity mapping using whole genome single nucleotide polymorphism (SNP) arrays and mutation analysis of CRB1. RESULTS: We recruited over 400 families with AR nonsyndromic retinal degenerations, including retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA). SNP array analysis was performed on 175 index cases, eight of whom carried a homozygous region on chromosome 1 harboring CRB1. A subsequent CRB1 mutation analysis of the eight families, followed by screening of candidate founder mutations in the whole cohort of patients, revealed a total of 13 mutations, six of which are novel, in 15 families. Nine mutations were family-specific and four were founder mutations identified in patients of Arab-Muslim origin and Jews originated from Iraq and Kurdistan. Interestingly, a null mutation on at least one of the two mutated CRB1 alleles results in the LCA diagnosis, whereas patients carrying missense mutations were diagnosed with either RP or LCA. The average age in which CRB1 patients were referred to ERG testing was young (11 years). Out of the 30 identified CRB1 patients, five developed Coats-like exudative vasculopathy. CONCLUSIONS: Our data show that CRB1 mutations are a relatively frequent cause of AR early-onset retinal degeneration in the Israeli and Palestinian populations (10% of LCA families) and causes severe retinal degeneration at an early age.Investigative ophthalmology & visual science 02/2013; 54(3). DOI:10.1167/iovs.12-11419 · 3.66 Impact Factor
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ABSTRACT: Introduction The purpose of this study was to determine whether topical 0.15% isopropyl unoprostone (IU), a BK-channel activator, could improve or maintain the central retinal sensitivity in patients with middle- to late-stage retinitis pigmentosa (RP). IU was approved for glaucoma and ocular hypertension in 1994. The drug re-profiling strategy is one of the effective ways to develop safe drugs for patients with RP. Methods A randomized, double-blind, and placebo-controlled phase II safety/efficacy trial was conducted. One hundred and nine patients with middle- to late-stage RP having a visual acuity of ≥0.5 were studied at six ophthalmological centers in Japan. The treatments of IU/day were divided into three groups: placebo group; two-drop group; and four-drop group for 24 weeks. The primary outcome measure was changes in the retinal sensitivity from baseline in the central 2° determined by MP-1 microperimetry (MP-1, Nidek, Japan). The secondary outcomes were changes in best-correct visual acuity, contrast sensitivity, retinal sensitivity of the central 10° by MP-1, mean deviation (MD) by a Humphrey field analyzer (HFA; Carl Zeiss Meditec, Dublin, CA, USA) 10-2, and the Visual Functioning Questionnaire 25 (VFQ-25) questionnaire scores. Results There was a tendency for a dose-dependent responsiveness in retinal sensitivity in the central 2°, MD, and total VFQ-25 score after 24 weeks of IU instillation by a simple linear regression analysis. A stratified analysis showed a significant dose-dependent responsiveness of the 2° central retinal sensitivity in more advanced patients (P = 0.028). The number of patients having a ≥4 dB decrease in the primary outcome measure was significantly fewer in the four-drop group than in the placebo group (P = 0.02). No adverse reactions were observed. Conclusions A higher dose of IU can delay progression of the central retinal sensitivity decrease through an improvement of retinal sensitivity.12/2012; 1(1). DOI:10.1007/s40123-012-0005-9
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ABSTRACT: PURPOSE. To investigate visual function and outer and inner retinal structure in the rare form of retinal degeneration (RD) caused byTULP1 (tubby-like protein 1) mutations. METHODS. RD patients with TULP1 mutations (n=5; age range, 5-36 years) were studied by kinetic and chromatic static perimetry, en face autofluoresence imaging and spectral-domain optical coherence tomography (OCT) scans. Outer and inner retinal laminar thickness were measured and mapped across the central retina. Comparisons were made with results from patients with RD associated with four ciliopathy genotypes (MAK, RPGR, BBS1 and USH2A). RESULTS. The TULP1-RD patients were severely affected already in the first decade of life and there was rapidly progressive visual loss. No evidence of rod function was present at any age. Small central islands showed melanized retinal pigment epithelium by autofluorescence imaging and well-preserved photoreceptor laminar thickness by OCT imaging. There was extracentral loss of laminar architecture and increased inner retinal thickening. Structure-function relationships in residual foveal cone islands were made in TULP1-RD patients and in other retinopathies considered ciliopathies. TULP1-RD patients, unlike the others, had greater dysfunction for the degree of foveal structural preservation. CONCLUSIONS. TULP1-RD leads to a small central island of residual foveal cones at early ages. These cones are less sensitive than expected from the residual structure. The human phenotype is consistent with experimental evidence in the Tulp1 knockout mouse model that visual dysfunction could be complicated by abnormal processes proximal to cone outer segments.Investigative Ophthalmology & Visual Science 07/2014; 55(8). DOI:10.1167/iovs.14-14570 · 3.66 Impact Factor