Melatonin Provides Anxiolysis, Enhances Analgesia, Decreases Intraocular Pressure, and Promotes Better Operating Conditions During Cataract Surgery Under Topical Anesthesia Salah A. Ismail, MBBch, MSc, MD Hany A. Mowafi, MBBch, MSc, MD 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 premedi- cation 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) com- pared with the control group, 0, 0 –32.5 vs 47.5, 30 – 65 g, 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 under- going cataract surgery under topical anesthesia provided anxiolytic effects, en- hanced analgesia, and decreased IOP resulting in good operating conditions. (Anesth Analg 2009;108:1146 –51) Phacoemulsification cataract surgery is commonly performed under topical anesthesia. Topical anesthe- sia is a noninvasive and simple modality that is free from vision interruption, ecchymosis, and other injec- tion complications. 1 Painless cataract surgery under topical anesthesia without systemic analgesia and/or sedation is possible and desirable. However, some patients may express pain and discomfort during iris manipulation, irrigation aspiration, and lens implan- tation. 1 Differences in pain sensitivity among indi- viduals or increased intraocular manipulations can also cause pain. Surgical pain causes patient anxiety and agitation with undesirable effects. 2 In such cases, systemic analgesia and/or sedation might be required to relieve patient discomfort and increase a patient’s tolerance to surgery. The commonly used analgesic and sedative drugs have drawbacks and limitations, such as respiratory depression, disorientation, exces- sive sedation, or excitation. A premedicant that re- duces analgesic requirements would be of value. Melatonin is a hormone secreted by the pineal gland. Several studies reported that melatonin has analgesic potential in addition to anxiolytic and sedative effects without disturbances of the cognitive and psychomotor skills, and thus improves the quality of recovery. 3– 6 In addition, it has been shown in previous experimental and human studies that melatonin reduces intraocular pressure (IOP). 7,8 These beneficial effects may be valu- able when melatonin is used as a premedicant for cataract surgery. Our primary hypothesis was that mel- atonin premedication would decrease pain and anxiety scores and reduce the need for analgesic medication during cataract surgery under topical analgesia. Second- ary objectives include evaluation of its effect on IOP and hemodynamics. The aim of this study was to evaluate the effects of melatonin premedication in patients under- going elective phacoemulsification cataract surgery during topical anesthesia along with the incidence of adverse effects. From the Department of Anesthesiology, Faculty of Medicine, King Faisal University, Saudi Arabia. Accepted for publication September 17, 2008. Address correspondence and reprint requests to Dr. Hany A. Mowafi, Department of Anesthesiology, King Fahd University Hospital, PO Box 40081, Al-Khobar 31952, Saudi Arabia. Address e-mail to hany_mowafi@hotmail.com. Copyright © 2009 International Anesthesia Research Society DOI: 10.1213/ane.0b013e3181907ebe Vol. 108, No. 4, April 2009 1146