Comparing Rod and Cone Function with Fundus Autofluorescence Images in Retinitis Pigmentosa

Abstract

In vivo recording of human retinal pigment epithelium (RPE) autofluorescence (AF) using a scanning laser ophthalmoscope has proved a useful technique in the investigation of inherited and acquired retinal disease (Von Ruckman et al., 1995; 1999; Delori et al., 1995a; Holz et al., 1999; 2001; Lois et al., 1999; 2001; Kurz-Levin et al., 2002). The emission spectrum of AF resembles that of lipofuscin (Eldred and Katz, 1988; Delori et al., 1995b) and the technique uniquely allows visualisation of lipofuscin at the level of the RPE. Abnormal high density AF results from accumulation of lipofuscin and may be due to disrupted metabolism at the level of the RPE (Kennedy et al., 1995). Lipofuscin may itself have deleterious effects: the dominant fluorophore, A2E, may cause short-wavelength induced death of the RPE and detergent like disruption of cell membranes (Sparrow et al., 2002). The absence of AF may indicate photoreceptor cell death leading to RPE atrophy. However, the presence of abnormal AF suggests continuing metabolic demand possibly representing compromised RPE function before cell death.