A neodymium-YAG endolaser

We used a CW-YAG endolaser to photocoagulate the fundus of the rabbit and monkey. We varied the power settings, exposure durations, and probe-retina distances to establish the parameters for threshold and bursting (choroidal hemorrhage) lesions. We found that the amount of energy needed to create a retinal lesion increased proportionally with the distance between the probe and the retina. To produce a choroidal hemorrhage at a given distance required at least four times the power required for a threshold coagulative lesion at the same distance. We also found that we could achieve a strong choroidal reaction without hemorrhage by using the coagulative threshold parameters of power and distance with an increased exposure time. Photocoagulation of the retina using the CW-YAG depended on the presence of melanin.