Chorioretinal vascular anastomoses resulting from photocoagulation in cynomolgus monkeys.

We studied the effects of intense argon laser photocoagulation in cynomolgus monkeys to determine whether or not anastomosis between the choroidal circulation and the major retinal arterioles could be produced. Chorioretinal vascular anastomosis occurred in nine of 19 sites in which photocoagulation was intense enough to occlude a major retinal arteriole and create disruption between the choroidal and retinal vasculatures. Anastomosis was seen by fluorescein angiography during the healing phase after treatment--none occurred earlier than seven weeks after photocoagulation. As a result of the anastomosis, previously nonperfused retinal blood vessels became reperfused (with choroidal blood). This model suggests future applicability in reperfusing segments of retinal arterioles or venules that have been obstructed by naturally occurring pathologic processes. The remaining ten treated sites showed no anastomosis, even through histologic studies showed that photocoagulation produced chorioretinal disruption and hemorrhage. None of the eyes developed neovascularization.