Angioarchitecture of the human choroid.

The angioarchitecture of the human choroid was studied by corrosion vascular casts and scanning electron microscopy. The relationship of the large choroidal arteries and veins, medium-sized arteries and veins, precapillary arterioles and postcapillary venules, and the choriocapillaris is described. At the posterior pole, a lobular arrangement of the choriocapillaris is seen. At the equatorial area, the capillaries run a more direct course, joining the precapillary arterioles to the capillary venules in a spindle-shaped segment of the choroidal vasculature. At the periphery, the choroidal arterioles and venules take a parallel course, with the choriocapillaris joining the adjacent arterioles and venules at a right angle and appearing in a ladder pattern. The regional variation of the angioarchitecture of the human choroid provides supporting evidence for the unique regional characteristics of choroidal blood flow.