Histologic studies of angle structures after laser iridotomy in primates.

Each of nine eyes of five cynomolgus monkeys had argon laser peripheral iridotomies performed to investigate the histologic effects on the trabecular meshwork. The laser technique was the same as is used in human eyes. With laser iridotomy, particulate debris was released into the anterior chamber and rapidly accumulated in the angle. The densest initial deposit was in the inferior juxtacanalicular trabecular meshwork. Histologically, pigment was located both extracellularly and within giant vacuoles of the endothelium and Schlemm's canal and intracellularly within trabecular endothelial cells. This finding indicates that this pigment is removed from the anterior chamber both by bulk aqueous flow and by phagocytosis. One year after iridotomy, only a slightly increased pigmentation of the angle was still present. No permanent ultrastructural damage to the angle was detected.