Intranasal Dexmedetomidine for Adult Patients Undergoing Phacoemulsification Cataract Surgery

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. \-