Usher syndrome linked to more vision loss than asymptomatic retinitis pigmentosa
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Usher syndrome type 2 caused greater visual field loss than asymptomatic retinitis pigmentosa, according to data presented at the Association for Research in Vision and Ophthalmology annual meeting.
“Patients who had Usher syndrome had worse visual field sensitivity or ability to see off to the side than those who had retinitis pigmentosa without any hearing loss. This measurement that we made — a quantitative measurement of side vision using a particular algorithm — was a very sensitive and reliable way of measuring visual field in patients with retinal degenerations,” Jacque Duncan, MD, Professor of Clinical Ophthalmology, Department of Ophthalmology, University of California, told Healio.
In the RUSH2A trial, investigators used an intra-class coefficient over a 4-year multicenter study to assess reproducibility of triplicate full-field static perimetry and between-eye symmetry of visual areas of kinetic perimetry. They used general linear models to assess the association of demographic and clinical characteristics with total hill of vision (VTOT) from SP. Association between VTOT, visual acuity, macular sensitivity on fundus-guided microperimetry, ERG amplitudes and latencies and standard definition-OCT measures of central subfield thickness within the center 1 mm and presence of intraretinal cysts was evaluated using Spearman correlation coefficients and t-tests.
Researchers reported baseline data on visual field testing — including reproducibility — and its relationship with baseline characteristics with other functional and structural measures.
According to the study results, 80 participants with USH2A-related Usher syndrome had more severe visual field loss compared with 47 participants with USH2A-related non-syndromic retinitis pigmentosa even after adjusting for duration of disease and age of vision loss onset (P = .002). The volumetric measure of VTOT was very reproducible and significantly correlated with other functional and structural metrics, indicating it may be a good summary measure of disease severity for patients with USH2A-related retinal degeneration.
“This is important for the development and design of clinical trials as more is understood about retinal degenerations. From a genetic standpoint, clinical trials of treatments are being developed, and it’s sometimes difficult to know what the best way to measure whether the treatment is safe and effective,” Duncan said. “Our study identified a very quantitative, reliable measure of visual field sensitivity for clinical trials going forward.
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Duncan, JL. Baseline visual fields in the RUSH2A study: Associated factors and correlation with measures of disease severity. Presented at: Association for Research in Vision and Ophthalmology annual meeting; May 14, 2020 (virtual meeting).
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