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Karl Andersen, Lydia Sauer, Rebekah H Gensure, Martin Hammer, Paul S Bernstein; Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Retinitis Pigmentosa Reveals Inheritance-Dependent Phenotypic Variance. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1567.
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© ARVO (1962-2015); The Authors (2016-present)
Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) has recently emerged as a tool to metabolically characterize changes in retinal disease. In a prospective, cross-sectional study, we investigated fundus autofluorescence (FAF) lifetimes in patients with retinitis pigmentosa (RP) to test the hypothesis that FLIO can uniquely characterize phenotypic imaging differences in various genetic subtypes of RP.
33 patients (mean age 40.0 ± 17.0 years) with RP as well as an age-matched control group of 33 individuals were included in the study. The FLIO camera (Heidelberg Engineering, Heidelberg, Germany) was used to detect FAF decays in both a short (498-560 nm, SSC) and a long (560-720 nm, LSC) spectral channel. We investigated a 30° retinal field, and the mean fluorescence lifetime (tm) was calculated from a 3-exponential approximation. In addition to FLIO imaging, macular pigment measurements, macular OCT scans, fundus photographs, visual fields and fluorescein angiograms were recorded. Genetic studies were performed on all patients.
FLIO shows a typical pattern of tm in patients with RP. In peripheral atrophic regions, tm is significantly prolonged (SSC 419 ± 195 ps; LSC 401 ± 111 ps) as compared to the same region in healthy eyes (SSC 265 ± 53 ps; LSC 282 ± 43 ps), p<0.001. Within the relatively preserved macular region, ring-shaped patterns are found in FAF intensity and lifetime images. They are most distinctive in patients with RP inherited in an autosomal dominant manner and in those with Usher Syndrome. Patients with autosomal recessive inheritance show a milder ring-like pattern, and those with X-linked retinitis pigmentosa show no ring pattern. Central areas corresponding to macular pigment remain relatively unaffected.
FLIO uniquely presents a distinct and specific signature in eyes affected with RP. These prominent ring-like patterns show inheritance-dependent variation in nearly all cases, which may be indicative of genetically-determined pathological processes. Hyperfluorescent rings with short FAF lifetimes may provide insight into disease status and help predict further progression of retinal atrophy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1: General comparison of healthy and RP
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