The investigators designed this study to examine whether the intranasal dexmedetomidine, as a preoperative drug, could improve the satisfaction of adult patients undergoing phacoemulsification cataract surgery.

This is a prospective, double-blind, randomized controlled study. Patients over 65 years old were selected for phacoemulsification combined with intraocular lens implantation under topical anesthesia. Participants were randomly divided into two groups: dextrometropine group and placebo group, and were masked until the end of this study. Approximately 45 - 60 minutes before surface anesthesia, patients in the dextrometropine group were given dextrometropine (1.0μg.kg-1), patients in the placebo group were given the same amount of saline. The primary end point of this study is the patient satisfaction. Patient satisfaction was assessed using a 3-point satisfaction score on a scale. Anxiety of perioperative patients was assessed using a 4-point anxiety score on a scale. Secondary endpoints include blood pressure, heart rate, blood oxygen saturation, operation time, operative complications and adverse drug reactions.

Inclusion Criteria: Cataract patients over 65 years scheduled for elective phacoemulsification and intraocular lens implantation in Department of Ophthalmology, Guangzhou First People's Hospital will be recruited in this study. Recruited patients shall own normal intelligence and understanding capability and their best corrected visual acuity more than 0.1 in either eye.

Exclusion Criteria: 1) a known allergy or hypersensitivity to dextrometropine or other anesthetics; 2) a previous history of heart disease; 3) a heart rate (HR) <45 beats per minute (bpm); 4) a second- or third-degree atrioventricular block; 5) patients on antihypertensive drugs, such as α-methyldopa, clonidine, or other α2-adrenergic agonists; 6) asthma; 7) sleep apnea syndrome; 8) organ dysfunction; 9) patients with mental illness; and 10) the long-term use of sedatives and analgesics.

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