Microperimetry and fundus autofluorescence in patients with early age-related macular degeneration

Background: Early age-related macular degeneration (AMD) has been correlated with different functional alterations, but the exact relationship between fundus lesions and overlying sensitivity is not well known. The aim of this study was to compare fundus-related sensitivity (microperimetry) and fundus autofluorescence (FAF) of the macular area with drusen and pigment abnormalities in early AMD. Methods: 13 consecutive patients with early AMD and visual acuity of 20/20 were studied by means of microperimetry, which automatically analyses macular light differential threshold and fixation patterns. Fundus colour photo and FAF of the macular area were recorded on the same day. Microperimetry was exactly (topographically) superimposed over FAF images. Results: Macular sensitivity significantly decreased over large drusen (11.2 ± 5.6 dB, p<0.0001) and over pigment abnormalities (13.1 ± 3.6 dB, p<0.0001). When both characteristics were present the reduction was greater if compared with its absence (9.6 ± 4.3 versus 15.0 ± 4.5 dB, p<0.0001). Sensitivitity reduction was significant in areas with altered FAF when compared with areas with normal FAF (p<0.0001). Conclusions: Increased FAF in early AMD has a functional correlate exactly quantified by microperimetry. In retinal areas affected by early AMD retinal sensitivity deteriorates, despite good visual acuity. Microperimetry may allow the early detection of functional impairment caused by these lesions. Both microperimetry and FAF may be useful to monitor AMD progression.