Effect of oral clonidine on acute intraocular pressure rise after cataract extraction under general anaesthesia.

To evaluate the efficacy of preoperative oral clonidine (5 g/kg) in preventing ocular hypertension in the early period after cataract surgery with posterior chamber intraocular lens implantation under general anaesthesia. This was a randomized double-blind clinical trial comprising of 62 eyes in 62 patients with senile cataract without using any viscoelastics. They were randomly assigned into two groups for preoperative oral clonidine (5 g/kg) and placebo. Intraocular pressure (IOP) was measured 6,12 and 24 hours postoperatively. Mean differences of lOPs at 6 and 12 hours after surgery were significantly lower in clonidine group [+0.41 4.55 (p = 0.612), 0.06 3.62 (p = 0.922)] than placebo group [5.77 4.25 (p = < 0.001), 4.70 3.19p < 0.001)] but was more than preoperative intraocular pressures in both. There was no statistically significant difference between the mean IOP 24hours post operatively in the two groups. But compared to preoperative IOP less increase in mean IOP was seen in clonidine group when compared to placebo group. A single dose of oral clonidine (5 g/kg) preoperatively can produce a significant IOP-lowering effect in early period after cataract surgery, specially in the first 12 hours.