Effects of carbachol and acetylcholine on intraocular pressure after cataract extraction.

We compared the effect of carbachol and acetylcholine on intraocular pressure 24 hours after extracapsular cataract extraction. All agents were administered intracamerally at the time of surgery. Sixty patients scheduled for routine extracapsular cataract extraction and intraocular lens implantation were randomly assigned into one of three treatment groups: (1) carbachol, (2) acetylcholine, or (3) 0.5% balanced salt solution (placebo). Baseline intraocular pressures were determined the day before surgery, and postoperative pressures were measured approximately 24 hours after surgery. The group intraocular pressures averaged over preoperative and postoperative values were 21.06 mm Hg in the acetylcholine group, 19.36 mm Hg in the control group, and 17.30 mm Hg in the carbachol group. The average difference between preoperative and postoperative intraocular pressure measurements for the three groups were 7.33 mm Hg for the acetylcholine group, 8.73 mm Hg for the control group, and 2.20 mm Hg for the carbachol group. Only carbachol was significantly different from placebo on statistical subsequent testing. Carbachol is suggested as the agent of choice both for achieving intrasurgical miosis and prophylaxis of increasing intraocular pressure after cataract surgery.