Increased Fundus Autofluorescence Associated with Outer Segment Shortening in Macular Translocation Model of Neovascular Age-Related Macular Degeneration

Abstract

To report the frequency and origins of increased fundus autofluorescence (AF) in age-related macular degeneration using the model of macular translocation. In this retrospective observational case series, postoperative serial fundus AF images from 40 consecutive patients were examined. The origin of well-delineated increased AF changes was explored by examining simultaneous spectral-domain optical coherence tomography (SD-OCT) scans and coregistered microperimetry. AF images were taken between a mean of 13 and 36 months. Seven patients were excluded from analysis because of lack of postoperative AF imaging or extensive macular RPE atrophy. Of the remaining patients, 9 had masking pattern of foveal AF, 21 had small, round increased AF lesions in the fovea, and 3 had a near normal pattern of foveal hypo-AF. Parafoveal increased AF was seen in all 33 patients in 1 of 3 patterns: well-delineated homogenous increased AF patches (17), curvilinear increased AF bands (4), and speckled increased AF (12). Simultaneous SD-OCT showed loss of signal from the interface of the inner and outer segments of the photoreceptor cell layer with variable loss of outer nuclear layer thickness. Microperimetry showed subnormal retinal sensitivity in regions with increased AF. Parafoveal increased AF size remained stable for 2 to 5 years of follow-up. SD-OCT and microperimetry changes observed after translocation may be attributed to shortening of the outer segments. A corresponding reduction of visual pigment in the shortened outer segments may lead to an unmasking effect. Increased AF in some macular diseases may be attributed to unmasking of AF rather than to increased fluorophores within abnormal retina.