Prevention of the immediate intraocular pressure rise following argon laser trabeculoplasty.

A prospective, randomised double-masked study was undertaken to compare the effect of pretreatment with acetazolamide or placebo on the immediate intraocular pressure (IOP) rise following argon laser trabeculoplasty. One hundred eyes (100 patients) underwent 180 degree of laser treatment with a mean of 59 spots of 50 microns size and 800 to 1000 mW power. The IOP was measured during the first three hours after laser treatment, at 24 hours, and at two months. Forty-six patients (92%) in the placebo group had an immediate rise of IOP. The mean rise (SD) for these patients was 8.6 (7.1) mmHg. Fifteen patients (30%) in this group had an IOP rise of greater than 10 mmHg. Nine patients (18%) receiving acetazolamide had an immediate rise of IOP. The mean rise for these patients was 4.3 (3.1) mmHg, and no patient had an increase in IOP of greater than 8 mmHg. Acetazolamide appears to be effective in preventing a critical IOP rise after argon laser trabeculoplasty (p less than 0.0001).