Choriocapillaris flow impairment surrounding geographic atrophy correlates with disease progression

Purpose To evaluate the correlation between the choriocapillaris (CC) flow alterations around geographic atrophy (GA) and the GA yearly growth rate (yGR) in patients with dry age-related macular degeneration (AMD). Methods We retrospectively reviewed and analyzed spectral domain optical coherence tomography (SD-OCT) and SD-OCT angiography images of consecutive patients with GA acquired using the Cirrus OCT at the Doheny Eye Centers between 2015 and 2017. All eligible patients had one 6 x 6 mm OCTA scan acquired during the first visit (considered as baseline) and two fovea-centered 512 x 128 macular cubes (6 x 6 mm) acquired at baseline and after a minimum of 12 months. Main outcome measures The fundus images from the OCT volumes were used to manually delineate the GA area and calculate the yGR after square root transformation. The en-face angiogram at the level of the CC was analyzed for the percentage of flow voids (FV) outside the atrophic lesion (FV OUT ) and in the para- and peri-atrophy regions (FV 500 and FV 1000 respectively; two concentric 500 μm wide rings around the atrophy edge). These values, together with the difference between FV 500 and FV 1000 (ΔFV), were then correlated with the corresponding yGR. Results Thirty-three eyes of 23 patients were eligible for the analysis. The mean yGR was 0.23 ± 0.17 mm/years. At baseline, the mean FV OUT was 41.86 ± 2.71%, while FV 500 and FV 1000 were 46.4 ± 4.17% and 42.51 ± 2.65% respectively. The mean ΔFV was 3.89 ± 2.6%. While in the univariable analysis, the yGR was significantly associated with FV 500 and with ΔFV (both p < 0.001), in multivariable model the association remained significant only with ΔFV (p < 0.001). Conclusions Our study reports a correlation between the CC flow impairment around the atrophic lesions and their yGR in patients with GA. If replicated in future longitudinal studies, the choriocapillaris FV in the para-and peri-atrophy regions may prove to be useful parameters for evaluating the prognosis of these eyes.