Argon laser iridotomy on primary angle closure or pupillary block glaucoma.

Scanning and transmission electron microscopy were performed on peripheral iridectomy specimens from seven patients with failed pulsed argon laser iridotomies. Four to seven hours after the laser, severe edema, coagulation necrosis, focal vascular occlusion, and hemorrhage were present. Five days after the laser, cell detritus and collapsed cell processes were noted. Forty-two days after the laser, the anterior iris surface appeared considerably thinned and irregular. Eight and one-half months after the laser, the burn site displayed a dense matted appearance. Two years after the laser, the anterior iris showed a depression with pigment dispersion, irregular stroma, and disruption of the dilator muscle. The lack of inflammation could be due to the use of pulsed argon laser heat delivered at very short intervals, with deep penetration and minimal heat dispersion, since the beam is highly collimated.