Morphological and functional effects of Na2EDTA on the outflow routes for aqueous humor in monkeys

The chelating agent Na2EDTA was perfused through the anterior chambers of monkeys eyes in an attempt to find a concentration that would cause a rise in outflow facility without harming the cornea or anterior uvea. Na2EDTA (0.5 mM) proved effective in increasing the facility within 60 min. There were marked effects on the tissue at the iridocorneal chamber angle with loss of cell processes from the trabecular cells, ballooning of the juxtacanalicular region and the inner wall of Schlemm's canal into the canal and ruptures of the inner wall of Schlemm's canal. After 60 min of perfusion there were mild vascular changes in the ciliary muscle and the iris and more pronounced stasis and leukocyte extravasation at the base of the ciliary processes and in the pars plana region. The corneal endothelium tended to swell but only after prolonged perfusion. After interruption of the perfusion there was rapid reduction in outflow facility, that seemed to be due to occlusion of the ruptures in Schlemm's canal by thrombocytes.