Background: Melatonin has anxiolytic and potential analgesic effects. In this study, we assessed the effects of melatonin premedication on pain, anxiety, intraocular pressure (IOP), and operative conditions during cataract surgery under topical analgesia.
Methods: Forty patients undergoing cataract surgery under topical anesthesia were randomly assigned into two groups (20 patients each) to receive either melatonin 10 mg tablet (melatonin group) or placebo tablet (control group) as oral premedication 90 min before surgery. Anxiety scores, verbal pain scores, heart rate, mean arterial blood pressure, and IOP were recorded. In addition, the surgeon was asked to rate operating conditions.
Results: Melatonin significantly reduced the anxiety scores (median, interquartile range) from 5, 3.5-6 to 3, 2-3 after premedication and to 3, 2-3.5 during surgery (P = 0.04 and P = 0.005 compared with the placebo group, respectively). Perioperative verbal pain scores were significantly lower in the melatonin group with less intraoperative fentanyl requirement (median, interquartile range) compared with the control group, 0, 0-32.5 vs 47.5, 30-65 microg, respectively, P = 0.007. Melatonin also decreased IOP (mean +/- sd) significantly from 17.9 +/- 0.9 to 14.2 +/- 1.0 mm Hg after premedication and to 13.8 +/- 1.1 mm Hg during surgery (P < 0.001). It also provided better quality of operative conditions.
Conclusion: We concluded that oral melatonin premedication for patients undergoing cataract surgery under topical anesthesia provided anxiolytic effects, enhanced analgesia, and decreased IOP resulting in good operating conditions.