Abstract
Purpose: :
Fundus autofluorescence (FAF) is a measure of lipofuscin accumulation in the retina, which reflects the activity of both the retinoid cycle and the ability of the retinal pigment epithelial (RPE) to phagocytose the photoreceptor (PR) outer segments. Our purpose was to determine the baseline characteristics of FAF in blind patients with retinitis pigmentosa (RP) due to LRAT mutations. FAF is potentially a useful measure of viability of the PR-RPE interface and clinical response to gene replacement or drug therapy in currently ongoing LCA and RP treatment trials. Previously FAF has not been shown in patients with LRAT mutations.
Methods: :
RP patients with LRAT mutations were tested for FAF and OCT by the Heidelberg Spectralis, using the 488 nm blue light stimulus. Genotyping was done by Sanger sequencing and confirmed by a CLIA lab. Patients were age-matched and best corrected ETDRS visual acuities and Goldmann visual fields were measured. Correlations were made between baseline FAF patterns, VA, VF, age, genotypes and OCT results.
Results: :
Patients with RP due to LRAT mutations were tested. Unlike previous studies, we found that RP patients with LRAT mutations maintain some FAF signals, albeit abnormal. We found two very different patterns of autofluorescence, including 1. A perifoveal band of FAF surrounding an absent center of FAF; 2. A peripheral macular stippling pattern of FAF. In this ongoing study, we are currently correlating these patterns with age, OCT parameters, genotype, mutation severity, visual fields and acuities.
Conclusions: :
We here report cases of RP due to LRAT mutations showing remaining FAF patterns. This is the first report of FAF patterns in RP patients with LRAT mutations. Despite the fact that LRAT mutations cause a block in the retinoid cycle, and prevent the formation of 11-cis retinal, we document lipofuscin accumulation, suggesting a low level of retinoid cycle activity. These FAF patterns may be helpful at baseline to determine efficacy and safety of drug or gene treatments, and identify progression patterns for RP due LRAT mutations.
Keywords: retina • retinal degenerations: hereditary • photoreceptors