Effect of clonidine on intraocular pressure following cataract surgery: a systematic review and meta-analysis

Background: Clonidine might be beneficial to the patients undergoing cataract surgery. However, the results remained controversial. We conducted a systematic review and meta-analysis to explore the effect of clonidine on intraocular pressure of patients undergoing cataract surgery. Methods: PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases were systematically searched. Randomized controlled trials (RCTs) assessing the effect of clonidine versus placebo on cataract surgery were included. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. The primary outcome was intraocular pressure. Meta-analysis was performed using random-effect model. Results: Four RCTs involving 210 patients were included in the meta-analysis. Overall, compared with control intervention, clonidine intervention was found to significantly reduce intraocular pressure (Std. mean difference =-0.84; 95% CI=-1.18 to -0.49; P<0.00001) and improve Ramsay Scale (Std. mean difference = 1.44; 95% CI=0.12 to 2.77; P=0.03), but showed no impact on heart rate (Std. mean difference =-0.38; 95% CI=-0.82 to 0.77; P=0.09) and arrhythmia (RR=0.32; 95% CI=0.03 to 3.84; P=0.37). Conclusions: Compared to control intervention, clonidine intervention was found to significantly reduce intraocular pressure and improve sedation, but showed no influence on heart rate and arrhythmia in patients undergoing cataract surgery.