The Role of Vitreous in AMD

Abstract

Purpose: : The stimuli for choroidal neovascularization in age-related macular degeneration (AMD) are not known. Recent studies (Krebs et al: AJO 144:741-6, 2007) detected posterior vitreous detachment (PVD) in 72% of eyes with dry AMD and vitreo-macular adhesion in 38% of eyes with wet AMD. This suggests that vitreo-macular adhesion may promote or at least facilitate choroidal neovascularization.The current investigation examined subjects with wet AMD in one eye and dry AMD in the fellow eye, to eliminate any influence of genetics and environment.Methodology: Subjects (n=24, mean age 80 + 6.3 years; 8 with geographic atrophy in the dry AMD eye) were evaluated by ultrasonography to determine the presence or absence of PVD and by OCT to detect vitreo-macular adhesion.

Results: : PVD was present in 18/24 (75%) eyes with dry AMD as compared to 7/24 (29.2%) eyes with wet AMD (P = 0.0005). Vitreo-macular adhesion was detected in 11/24 (45.8%) eyes with wet AMD as compared to 1/24 (4.2%) eyes with dry AMD (P = 0.0002).

Conclusions: : There is a strong association between the presence of PVD and dry AMD, suggesting that complete PVD may somehow protect against wet AMD. That vitreo-macular adhesion is associated with wet AMD in nearly half of all cases further supports the hypothesis that vitreous plays a role in the pathogenesis of wet AMD, possibly by inducing chronic, low-grade inflammation from vitreo-macular traction. Alternatively, the attached posterior vitreous cortex could have barrier properties, restricting the influx of oxygen and nutrients and/or the efflux of pro-angiogenic cytokines.

Keywords: age-related macular degeneration • vitreous • imaging/image analysis: clinical