Dexmedetomidine in Topical Versus Peribulbar Anesthesia for Cataract Surgery

Inclusion Criteria: * American Society of Anesthesiologists (ASA) physical status classification I or II who scheduled for eye surgery Exclusion Criteria: * Patients who are younger than 18 years * The usual contraindications for regional anesthesia such as patients refusing LA * Clotting abnormalities * Impaired mental status * Allergy to any of the study medications * patients had the severe cardiac disease * chronic obstructive lung disease and a history of sleep apnea * contraindications to the use of dexmedetomidine * history or significant cardiovascular disease risk factors * significant coronary artery disease or any known genetic predisposition * history of any kind of drug allergy * drug abuse * psychological or other emotional problems * special diet or lifestyle * clinically significant abnormal findings in physical examination * electrocardiographic (ECG) or laboratory screening * known systemic disease requiring the use of anticoagulants.