Abstract
Purpose :
Late-onset retinal degeneration (L-ORD) can often be misdiagnosed due to phenotypic variability and the disease mirroring more common diseases. This cross sectional observational study examines retinal function and visual outcome in a cohort of L-ORD participants to improve the understanding of this phenotype.
Methods :
All participants underwent full-field electroretinogram (ffERG), pattern electroretinogram (PERG) and LogMAR best corrected visual acuity (BCVA). Descriptive statistics used, averages reported as median ± standard deviation.
Results :
All 40 participants in the cohort had the missense mutation c.489C>G (p.Ser163Arg) in C1QTNF5. The median age of the cohort was 65.5 years (range 30 – 85). The median BCVA of the cohort is 0.09 ±0.74 logMAR. Following WHO classification of visual impairment, 27 (67.5%) of the participants had no or mild visual impairment (≤0.48 logMAR), 3 (7.5%) had a moderate impairment (>0.48 and ≤1.0 logMAR) and 10 (25%) were blind (>1.3 logMAR). Electrophysiological assessment showed 4 (10%) participants had normal retinal (ffERG) and macular (PERG) function, 3 (7.5%) had isolated rod dysfunction, 4 (10%) had a rod-cone pattern of dysfunction and 29 (72.5%) had rod-cone and macular dysfunction. The median ages of the groups showed an increase associated with severity of retinal involvement, 38.5, 47, 60 and 67 years, respectively. All participants with normal retinal function, isolated rod dysfunction or rod-cone dysfunction were classified as having no or mild visual impairment, BCVA of each group: -0.06 ± 0.07, -0.08 ± 0.11 and –0.01 ± 0.1 logMAR, respectively. However, in the sub-group with rod-cone and macular dysfunction, there appears to be at least two subgroups of visual outcome, 10 (34.5%) classified as blind and 16 (55.2%) classified as no or mild visual impairment. The remaining 3 participants were classified as moderately visually impaired (10.3%).
Conclusions :
The data demonstrates a clear disease trajectory through quantified changes in retinal function, from normal retinal function to isolated rod dysfunction and to rod-cone dysfunction with macular involvement. The phenotypic variability observed in the latter group, with presumed late-stage disease, in which over half (55.2%) show preserved visual outcome compared to the remaining 44.8%, classified as blind (34.5%) or moderately visually impaired (10.3%), require further study to explain this dichotomy.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.