Purpose
To report quantitative fundus autofluorescence (qAF) in patients with confirmed mutations in peripherin 2 (PRPH2/RDS).
Methods
PRPH2/RDS mutations were identified by direct Sanger sequencing in 6 patients (mean age of 48.7 years; range: 30-62 years) from 4 unrelated families. AF images (30°, 488 nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. For each image, gray levels (GLs) were measured in predefined fundus areas and calibrated to the reference, zero GL, magnification, and normative optical media density, to yield qAF. In addition, texture factor (TF) was measured in the same fundus areas as a metric of AF inhomogeneity.
Results
Fundus AF images had features ranging from unremarkable to varying densities of flecks and mottling and some patients exhibited geographic atrophy. Noticeably, the peripapillary area was spared in all subjects. Mixed-effects linear regression, which accounted for within-subject correlations between eyes and between close family members, indicated that qAF (p<0.001) and TF (p<0.001) in RDS eyes were elevated compared to healthy eyes. The spatial distribution of the AF signal appeared different from healthy eyes with the inferior side being relatively higher than in healthy subjects.
Conclusions
The qAF method, an indirect measure of RPE lipofuscin, revealed increased qAF levels in patients with RDS mutations. The mechanism by which RPE lipofuscin is increased in the presence of an RDS mutation is not known nor is it understood whether elevated lipofuscin is a component of the primary disease process.
Keywords: 696 retinal degenerations: hereditary •
582 ipofuscin •
550 imaging/image analysis: clinical