Use of argon laser energy to produce iridotomies

Laser iridotomy with the c-w argon laser and the pulsed argon laser has been performed in some 300 eyes, 215 of which are included in the present investigation. Using techniques described in this study, a laser iridotomy was made successfully in 95% of cases. However, in a series of 77 consecutively treated eyes that were followed at regular intervals for up to four years, 34% required retreatment. In no case did an iridotomy close if it remained patent for 6 weeks. The optimum results were obtained using a contact lens and a 50-mu or 100-mu laser spot with energy levels of 0.5 to 2.0 w for 0.2 sec. Larger spots and higher powers, even when combined with shorter pulses, were either less effective or produced superficial corneal burns. The ease with which an iridotomy could be made was partly dependent on iris color and thickness, corneal tolerance and deturgescence. However, success will, in large measure, depend on the technician's proficiency and experience. A test of patency was the visibility of lens capsule through the iridotomy. Even so, a mistaken estimation of patency could result if there were posterior synechiae around the margin of the iridotomy or if one failed to recognize the presence of a barely-visible fibrous membrane bridging the hole. Complications that occurred with laser iridotomy included corneal epithelial and endothelial burns, lens opacity behind the iris defect, and retinal burn. The lens opacity was found to be caused by localized fragmentation of lens fibers and atrophy of the lens epithelium. Iris angiography performed 6 to 36 months after laser iridotomy in human eyes failed to reveal any disturbance in vascular permeability and the blood-aqueous barrier. Laser iridotomy was considered the procedure of choice in monocular patients and for treating the fellow eye in persons who suffered a complicated peripheral iridectomy by surgery in one eye. The laser played an important role, not only in treatment, but also in diagnosis of chronic angle-closure and combined-mechanism glaucoma.