Early deterioration in ellipsoid zone in eyes with non-neovascular age-related macular degeneration
The purpose of this study was to investigate the early effects of soft drusen on retinal pigment epithelium (RPE), ellipsoid zone (EZ, photoreceptor inner segment/outer segment junction), and external limiting membrane (ELM) reflectivities using optical coherence tomography (OCT) image analysis. This retrospective comparative study comprised 47 patients with non-neovascular AMD (with intact RPE, EZ, and ELM bands on OCT) and 45 age- and sex-matched healthy controls with normal OCT. A single masked physician performed OCT image analysis using a medical image processing software. Reflectivities of RPE, EZ, and ELM; number of drusen; vertical and horizontal diameters of the largest druse; druse reflectivity; foveal involvement by a druse; and presence of ≥1 large druse (n) were evaluated based on the macular OCT scan. Forty-seven right eyes of 47 patients with non-neovascular AMD and 45 right eyes of 45 healthy subjects were recruited. In the non-neovascular AMD group, absolute EZ and RPE reflectivities were significantly lower compared to those of the control eyes (P < 0.001 and P = 0.001, respectively). Comparing relative reflectivity values, only relative EZ reflectivity (EZ/ELM reflectivity) remained to show a significant difference between the groups (P < 0.001). Correlation analyses revealed no significant relation between the reflectivity values and drusen characteristics (P > 0.05). In eyes with non-neovascular AMD, decreased RPE (only absolute) and EZ (both absolute and relative) reflectivities prior to the disruption of these layers on OCT might indicate early photoreceptor damage. However, lower reflectivity values appear to be independent of the drusen characteristics.