[The segmental characteristic of the human choroidal vessels and its clinical significance].

The segmental vascular supply and anastomosis of human choroidal vessels were studied in 10 subjects (20 eyes) by the corrosion cast technique and scanning electron microscopy. The distribution pattern of the choroidal vessels was characterized by distinct segmental arrangement of large vessels and lobular arrangement of choriocapillaries. Maximal choriocapillary density and caliber were observed in the posterior pole. The mean diameters of the choriocapillaries in the macular, the equatorial, and the peripheral areas were 25.19 + 0.99 microns, 22.42 + 1.07 microns, and 28.1 + 1.29 microns respectively. It was also revealed that interarterial anastomosis existed among large arteries, precapillary arterioles, and even choriocapillaries. Veno-venous anastomotic communications were a general phenomenon. Therefore, the choroidal vessels are not true end-arteries anatomically. Obstructions at different levels of the choroidal arteries show corresponding clinical features. Occlusion in a posterior ciliary artery or a large choroidal artery is known as the triangular syndrome. Choriocapillary obstruction can be caused by many diseases. The relationship between the RPE and the choriocapillaries was discussed.