Purpose:

To quantify the regional variation in choriocapillaris (CC) flow deficits percentage (FD%) surrounding treatment-naïve Type 1 choroidal neovascularization (CNV) associated with age-related macular degeneration.

Methods:

Patients were imaged with swept-source optical coherence tomography angiography system (Carl Zeiss PLEX Elite 9000; Carl Zeiss Meditec AG, Jena, Germany). Two 6× 6-mm volume scans were acquired. Boundary-specific segmentation was used to isolate the Type 1 CNV. For CC assessment, both structural and optical coherence tomography angiography CC slabs (10-µm thick, starting 21 µm below the retinal pigment epithelium fit reference) were exported for signal compensation and averaging using ImageJ. The resultant CC image was binarized to calculate the FD%, for para-CNV and peri-CNV rings (each 500-µm wide). In a subgroup of 20 eyes, the FD% was compared with similar regions of age-matched controls. The FD% was also analyzed in small 500× 500-µm squares equidistant from the fovea to compensate for regional variation of CC FD% as a potential confounding factor.

Results:

Thirty-two eyes from 27 subjects were enrolled in this study. The CC FD% in the para-CNV ring was 26.58±7.36, which was significantly higher than the peri-CNV ring (21.94±6.31); P< 0.001. The FD% in para-CNV and peri-CNV rings was significantly greater than that of healthy controls (15.82±1.29% and 15.53±1.32%, respectively); P< 0.001. The FD% computed in the 500-µm squares equidistant from the fovea was also greater in the para-CNV ring (26.14±7.11) than that in the peri-CNV ring (22.31±6.21); P< 0.001.

Conclusion:

Choriocapillaris FD% is the highest in the region immediately surrounding the CNV.

Significant deficits in choriocapillaris flow can be observed surrounding choroidal neovascular lesions. The development of choroidal neovascularization in these regions of choriocapillaris flow impairment may provide insights into the pathophysiology of these lesions.