Purpose
Intraretinal hyperreflective foci evident on OCT in eyes with non-neovascular age-related macular degeneration (NNVAMD) are know to represent pigment migration (PM). The purpose of this study is to utilize three-dimensional OCT to assess the prevalence of PM and its distributional characteristics in eyes with early NNVAMD.
Methods
Patients with the clinical diagnosis of NNVAMD who underwent digital Color Fundus (Topcon 50IX, Topcon Co) and OCT (512x128 volumes) imaging (3D-OCT-2000, Topcon Corp, Tokyo, Japan) in both eyes, on the same day, between September 2006 and July 2009 at a retina subspecialty clinic were retrospectively reviewed. Eyes with evidence of atrophy, choroidal neovascularization (CNV), other retinal diseases or history of retinal surgery, and/or ungradable images (OCT or color) were excluded. Foci of PM were assessed by OCT as definitely present, questionably present, absent for each individual B-scan. If definite PM was observed, the number of individual PM foci on the B-scan, as well as the retinal layers involved by the migration, were also documented. Findings were tabulated across all B-scans for each eye, and the presence and frequency of PM in each retinal layer were computed for each ETDRS grid subfield.
Results
A total of 153 visits of 153 eyes from 111 patients met the inclusion criteria. The mean age of patients was 78.4 (range, 53-97) years. 43.8% eyes (67/153) with definite PM, and an additional 0.7% eyes (1/153) with questionable PM were observed by OCT and confirmed by color photos. For eyes with definite migration, 50.7% (34/67) of eyes with showed pigment in the photoreceptor cell layer (PR), 76.1% in the outer nuclear layer (ONL), 67.2% in the outer plexiform layer (OPL) and 40.3% in the inner nuclear layer (INL). When looking at the frequency (number of B-scans involved), we observed: 113 for PR, 522 for ONL, 353 for OPL, and 140 for the INL. When analyzing the topographical distribution of pigment in accordance with the ETDRS grid, PM was most frequent in superior inner macula (SIM). However, the density of PM was greatest in the central subfield (2.58 foci/eye*mm2).
Conclusions
Three-dimensional OCT scanning can permit the study of the distribution of pigment migration in eyes with NNVAMD. These findings may provide new insights into the pathogenesis and progression of this disease.
Keywords: 550 imaging/image analysis: clinical •
412 age-related macular degeneration