Changes in Retinal Layer Thickness in the Contralateral Eye of Patients with Unilateral Neovascular Age-Related Macular Degeneration

Purpose: To evaluate the thickness of the outer retinal layers and its relationship with visual function in fellow eyes of participants with unilateral neovascular age-related macular degeneration (AMD). Design: Longitudinal study. Participants: We enrolled 105 subjects with unilateral neovascular AMD from 3 clinical centers in Europe. Methods: The fellow eye, without advanced AMD, was selected for the study. Subjects were followed up with visits occurring every 6 months for 2 years. Spectral domain optical coherence tomography volume scans were collected at 3 clinical sites, in Belfast, Northern Ireland; Coimbra, Portugal; and Milan, Italy. Detailed manual segmentation of outer retinal layers was performed using the custom-designed and validated grading software 3D OCTOR. Thickness measurements for neurosensory retina, photoreceptor layer (PRL) outer segments, retinal pigment epithelium plus drusen (RPE+drusen) complex, and choroidal layers from each sector of the standard macular grid were obtained. Measures of vison were distance visual acuity, near visual acuity, Smith-Kettlewell Institute low-luminance acuity score, and reading speed. Subjects were grouped based on the presence or absence of subretinal drusenoid deposits (SDDs) for further analysis. Main Outcome Measures: Change in thickness of retinal layers and change in measures of vision. Results: In all, 85 eyes were included in the analysis. The average duration of follow-up was 20.5 ± 5.8 months. By the final visit, the RPE+drusen complex was significantly thinner when compared with baseline (29.7 μm vs. 34.09 μm; P = 0.03). Low-luminance deficit was significantly worse at the final visit (P < 0.001) and correlated with PRL outer segment thickness (r = 0.33; P =0.02). The RPE+drusen complex was significantly thicker in eyes with SDDs compared with that in those without SDDs (30.67 μm vs. 28.64 μm; P = 0.02). PRL outer segments became significantly thinner over time in eyes with SDDs compared with those in eyes without SDDs. Conclusions: The RPE+drusen complex layer becomes thinner over time in fellow eyes of subjects with unilateral neovascular AMD. The rate of PRL outer segment thinning was higher in eyes with SDDs than in eyes without SDDs. These findings are preliminary steps in the identification of early biomarkers for detecting and monitoring the progression of AMD.