Retinal and choroidal changes in AMD: A systematic review and meta-analysis of spectral-domain optical coherence tomography studies

Optical coherence tomography is a noninvasive imaging technology using the optical reflectivity of tissues that is capable of detecting quantitative and qualitative biomarkers of age-related macular degeneration (AMD) that cannot be similarly recognized in conventional imaging. We systematically searched PubMed and Embase databases to identify relevant articles to this subject. A fixed-effect or random-effect model was applied for the meta-analysis based on the heterogeneity level. In addition, subgroup analyses, meta-regression, publication bias, and quality assessment were also performed. Twenty-five studies with 1,632 cases and 1,445 healthy controls in total were included. Our results revealed that, when compared to controls, AMD subjects showed a significantly lower thickness in the choroid at 500 µm temporal, 1,500 µm nasal, and temporal to the fovea, subfoveal choroid, average peripapillary retinal nerve fiber layer, and average macular ganglion cell complex (GCC); however, average and central choroidal thickness 500 µm nasal, 1,000 µm nasal and temporal to the fovea, central and parafoveal macular GCC, retinal nerve fiber layer, and inner plexiform layer, and central macular thickness did not change significantly. Various regional analyses showed several other significant differences. The findings of the current study confirm that some retinal layers are altered in AMD patients compared to healthy controls. Thus, future studies are required to derive more definitive conclusions.