Choriocapillaris impairment around the atrophic lesions in patients with geographic atrophy: a swept-source optical coherence tomography angiography study

Aims To evaluate the choriocapillaris (CC) flow alterations around geographic atrophy (GA) in eyes with dry age-related macular degeneration. Methods Using a swept-source optical coherence tomography angiography (SS-OCTA) device, two volume 6x6 mm scans were acquired in patients with GA presenting between June and December 2017 at the Doheny-UCLA Eye Centers. The area of GA was delineated on the en face structural OCT fundus images. For each eye, the en face OCTA slabs at the level of the CC from the two acquisitions were averaged and compensated for signal loss using the corresponding structural en face images. The resulting images were binarised and analysed for the percentage of flow voids in the para-atrophy zone (a 500 mu m wide ring around the immediate edge of the atrophy) and in the peri-atrophy zone (a 500 mu m wide ring around the para-atrophy zone edge), the latter considered as a reference in the comparative analysis. Results Thirty eyes of 20 patients were enrolled. The percentage of flow voids in the para-atrophy zone was 27.23%+/- 6.29% and was significantly higher than in the surrounding peri-atrophy zone (23.4%+/- 6.01%; p<0.001). There was no significant correlation between the flow void percentage in these regions and age, visual acuity, extent of the atrophic area or central choroidal thickness. Conclusions A significant impairment of the CC flow is present in the zone immediately surrounding the GA lesions strengthening the hypothesis that CC alterations may be relevant to the progression of GA.