Autofluorescence Lifetimes in Patients With Choroideremia Identify Photoreceptors in Areas With Retinal Pigment Epithelium Atrophy

PURPOSE. The purpose of this study was to investigate fundus autofluorescence lifetimes in patients with choroideremia and to identify tissue-specific lifetime characteristics and potential prognostic markers. METHODS. Autofluorescence lifetimes of the retina were measured in two spectral channels (498-560 nm and 560-720 nm) in patients with choroideremia and age-matched healthy controls. Furthermore, autofluorescence intensities and spectral-domain optical coherence tomography (OCT) data were acquired and compared to fundus autofluorescence lifetime data. RESULTS. Sixteen eyes from 8 patients with advanced choroideremia (mean +/- SD age, 55 +/- 13 years) were included in this study and compared with 10 age-matched healthy participants. Whereas fundus autofluorescence intensity measurement identified areas of remaining retinal pigment epithelium (RPE), autofluorescence lifetime maps identified areas with remaining photoreceptor layers in OCT but RPE atrophy. In these areas, mean (+/- SEM) lifetimes were 567 +/- 59 ps in the short and 603 +/- 49 ps in the long spectral channels (+98% and +88% compared to controls). In areas of combined RPE atrophy and loss of photoreceptors, autofluorescence lifetimes were significantly prolonged by 1116 +/- 63 ps (+364%) in the short and by 915 +/- 52 ps (+270%) in the long spectral channels compared with controls. CONCLUSIONS. Because autofluorescence lifetimes identify areas of remaining photoreceptors in the absence of RPE, this imaging modality may be useful to monitor disease progression in the natural course of disease and in context of potential future therapeutic interventions.