Choroidoretinal vascular anastomoses.

Three cases of choroidoretinal anastomosis had unusual etiologic and hemodynamic features. In two cases the anastomoses, one caused by ocular histoplasmosis and one by diabetic maculopathy, shunted retinal venous drainage into the choroid. In the third case, the congenital arterial choroidoretinal anastomosis should probably be termed retinochoroidal arteriovenous anastomosis. Prospective photographic and fluorangiographic studies of these patients suggest that our understanding of many basic features of retinal-choroidal circulatory hemodynamics is incomplete.