Vortex vein congestion in the monkey eye: A possible animal model of pachychoroid

Purpose To create vortex vein congestion in the monkey eye as a possible pachychoroid model. Methods We ligated superotemporal and inferotemporal vortex veins at the surface of the sclera in monkey eyes. Optical coherence tomography (OCT) and indocyanine green angiography (ICGA) were performed before and 2, 7, and 28 days after the vortex vein ligations to investigate changes in vortex vein morphology and alterations in choroidal blood flow. Results Before the vortex vein ligations, en face OCT and ICGA images showed well organized vortex veins as well as horizontal and vertical watershed zones. Two days after the vortex vein ligations, dilatation of the superotemporal and inferotemporal vortex veins as well as intervortex venous anastomoses were seen on en face OCT and ICGA images. B-mode OCT images showed choroidal thickening associated with dilatation of the outer choroidal vessels. Moreover, video ICGA revealed choriocapillaris filling delay and pulsatile flow in the dilated vortex veins. At 7 and 28 days after we ligated the vortex veins, these findings were reduced, except for the intervortex venous anastomoses. Conclusions We created a monkey model of vortex vein congestion by ligating two vortex veins. This animal model demonstrated pachychoroid-related findings, indicating that vortex vein congestion is involved in the pathogenesis of pachychoroid. However, remodeling of the choroidal drainage route via intervortex venous anastomosis appeared to compensate for the vortex vein congestion created in this model.