Choroidal structures in polypoidal choroidal vasculopathy, neovascular age-related maculopathy, and healthy eyes determined by binarization of swept source optical coherence tomographic images

Purpose To evaluate quantitatively the choroidal vascularity in polypoidal choroidal vasculopathy (PCV) and neovascular age-related macular degeneration (AMD) patients compared to healthy controls. Methods All eyes underwent swept source optical coherence tomography (OCT), and choroidal images were binarized into blood vessels lumen and stroma. The choroidal vascular index (CVI) was defined as the ratio of luminal area (LA) over total choroidal area of the subfoveal region with a width of 1500 mu m. Results The study included 73 patients with neovascular AMD or PCV with mean +/- standard deviation (SD) age of 71.8 +/- 9.3 years, which was older than the mean age of 65.1 +/- 10.8 years of 72 healthy eyes from control group (p < 0.01). The 44 PCV eyes had significantly higher mean SFCT of 214.23 +/- 95.21 mu m than neovascular AMD eyes (172.74 +/- 96.48 mu m, p = 0.03) and greater luminal area (0.23 +/- 0.09 mm(2) vs. 0.19 +/- 0.08 mm(2), p = 0.05). After adjusting for age, axial length, and gender in multivariate regression analysis, the SFCT of PCV and neovascular AMD eyes were not significantly different from healthy eyes (195.55 +/- 93.11 mu m), but the CVI of both PCV (64.94 +/- 5.43%, p = 0.01) and neovascular AMD (62.54 +/- 5.57%, p = < 0.01) were significantly lower than control (68.53 +/- 5.91%). Conclusion Despite physiological changes of choroidal vasculature due to aging, the choroidal morphology is different in PCV, neovascular AMD and healthy eyes, which has implication on disease pathogenesis.