The effect of betaxolol and timolol on postoperative intraocular pressure.

Postoperative intraocular pressure (IOP) elevation is a well documented phenomenon after cataract surgery. Many pharmacological agents have been used to prevent this complication. We conducted a randomized double-blind, placebo-controlled study to evaluate the effect of topical betaxolol and timolol on postoperative IOP after extracapsular cataract extraction and intraocular lens implantation. One hundred and twenty patients were randomly divided into three groups. At the end of the operation, the patients were given one drop of 0.5% betaxolol, 0.5% timolol or placebo solution into the lower cul-de-sac of the operated eye. IOP was measured preoperatively and five and twenty-four h postoperatively. There was a significant rise in IOP in the placebo and betaxolol groups but not in the timolol group five h postoperatively. IOP was significantly higher in all groups twenty-four h after the operation than preoperatively. Betaxolol did not have any significant effect on the postoperative IOP, but timolol was effective in preventing the early IOP rise. The differences in the antagonist effects of these drugs and the possible role of beta 2-receptors in mediating the aqueous humour flow are discussed.