Topographic Variation of the Growth Rate of Geographic Atrophy in Nonexudative Age-Related Macular Degeneration: A Systematic Review and Meta-analysis

PURPOSE: To determine the impact of topographic locations on the progression rate of geographic atrophy (GA). METHODS: We searched in five literature databases up to May 3, 2019, for studies that evaluated the growth rates of GA lesions at different retinal regions. We performed random-effects meta-analyses to determine and compare the GA effective radius growth rates in four location groups defined by two separate classification schemes: (1) macular center point involved (CPI) or spared (CPS) in classification 1, and (2) foveal zone involved (FZI) or spared (FZS) in classification 2. We then estimated the GA growth rate in eight topographic zones and used the data to model the GA expansion. RESULTS: We included 11 studies with 3254 unique eyes. In studies that used classification 1, the effective radius growth rate was 30.1% higher in the CPS group (0.203 ± 0.013 mm/year) than in the CPI group (0.156 ± 0.011 mm/year) (P < 0.001). This trend became significantly more prominent in classification 2, where the growth rate was 61.7% higher in the FZS group (0.215 ± 0.012 mm/year) than in the FZI group (0.133 ± 0.009 mm/year) (P < 0.001). The estimated GA effective radius growth rates in eight retinal zones fit a Gaussian function, and the modeling of GA expansion gave rise to various GA configurations comparable to clinical observations. CONCLUSIONS: This study indicates that the GA progression rate varies significantly across different retinal locations. Our analysis may shed light on the natural history and underlying mechanism of GA progression.