Effect of intracameral carbachol on intraocular pressure after cataract extraction.

Thirty-two patients were randomly assigned to a treatment or a control group to determine the dose-response and duration of action of intracameral carbachol on immediate postoperative intraocular pressure after extracapsular cataract extraction using a viscoelastic substance. Patients in the treatment group received 0.5, 0.25, or 0.1 ml of 0.01% intracameral carbachol. Patients in the control group received 0.1 or 0.5 ml of balanced salt solution. Intraocular pressures of all patients were measured preoperatively and at three, six, 12, 24, and 48 hours postoperatively. The control group as a whole showed a 9.5-mm Hg intraocular pressure rise at three hours, a 10.0-mm Hg rise at six hours, a 9.0-mm Hg rise at 12 hours, and a 7.2-mm Hg rise at 24 hours postoperatively. The group treated with 0.5 ml of carbachol maintained stable intraocular pressures through the 48-hour measurement period. The groups treated with 0.25 and 0.1 ml of carbachol maintained stable intraocular pressures through 24 hours postoperatively. The differences in intraocular pressure were statistically significant for all treated groups through the 24-hour measurement.