The effect of low dose of ketamine on intraocular pressure in patients undergoing cataract surgery

Background: Cataract surgery is one of the most common surgeries in the world, especially in elderly patients, and often performed topically with sedative agents. Ketamine is one of the most commonly used agents and the effect of different doses on intraocular pressure is in dispute. The present study investigates the effect of a low dose of ketamine on intraocular pressure in patients undergoing cataract surgery. Methods: This case-control study was performed in Farabi Hospital, Tehran University of Medical Sciences from January 2020 to February 2020. In this study 92 patients undergoing cataract surgery were randomly divided into two groups of 46 patients. Patients' intraocular pressure and blood pressure were measured at baseline, and then all patients received 1 mg midazolam and 1 μg/kg fentanyl before initiation of the study. In the case group, 0.15 mg/kg ketamine was injected intravenously. Intraocular pressure and blood pressure of all subjects were measured three minutes after injection of sedation. Also, postoperative pain, need for opioids and, postoperative nausea and vomiting were compared between the two groups. Results: There was no significant difference in age, sex and weight between the two groups. Mean intraocular pressure in both groups was not significantly different at baseline. The trend of changes in intraocular pressure was lower in both groups after sedation and there was no statistically significant difference between the two groups. After sedation injection, the mean arterial blood pressure changes in the control group were decreasing while in the case group showed an increasing trend and this difference was statistically significant. Five patients in the control group and one in the case group complained of moderate to severe pain postoperatively. There was no significant difference between the two groups regarding nausea and vomiting and the need for postoperative opioids. Conclusion: Low-dose ketamine administration had no significant effect on intraocular pressure and did not cause side effects of ketamine such as nausea, vomiting and hallucinations and it may improve the hemodynamic stability of patients if they are injected with sedative medications.