Discrete arcs of increased fundus autofluorescence in retinal dystrophies and functional correlate on microperimetry

Purpose To describe the occurrence of discrete arcs of increased fundus autofluorescence (FAF) associated with various retinal dystrophies and to assess their functional significance by fundus-controlled microperimetry. Methods Seven patients, three with pigmented paravenous retinochoroidal atrophy (PPRCA), one with sector retinitis pigmentosa (RP), one with typical RP, and two with macular dystrophy were assessed by retinal imaging including FAF imaging. Serial images were obtained within a review period of 6 and 10 years in a patient with PPRCA and macular dystrophy, respectively. Fundus-controlled microperimetry was performed in eight eyes of five patients to determine light increment sensitivity. Results A discrete arched line of increased FAF was observed without obvious correlate on fundus biomicroscopy. The orientation of this line differed from ring shape in RP and macular dystrophy, a semi-circle structure in sector RP to crescent shape with tiplike extensions towards branching retinal veins in PPRCA. Longitudinal investigation revealed slight migration of the arc in PPRCA and peripheral extension of the ring diameter in macular dystrophy. Microperimetry revealed that the arc of increased FAF sharply delineated areas of severely impaired retinal sensitivity. Conclusions The findings indicate that arcs of increased FAF in PPRCA and other retinal dystrophies demarcate areas of impaired retinal function and may migrate over time. FAF imaging may therefore reveal the exact extent of neurosensory dysfunction that may exceed the dimensions anticipated by conventional examinations.