Background: Regional anesthesia is a preferred technique for ophthalmic surgery. It is safe, inexpensive and provides efficient ocular anesthesia for ophthalmic surgery. It is associated with less hemodynamic instability, less respiratory depression, better postoperative pain relief, and less nausea and vomiting compared to general anesthesia. Among regional blocks, peribulbar block is safer in comparison with retrobulbar block due to a lesser incidence of serious complications such as brain stem anesthesia, globe perforation, and retrobulbar hemorrhage. Objective: The aim of the study was to compare the safety and efficacy of the use of Magnesium sulfate versus that of Dexmedetomidine as an adjuvant to the local anesthetic in peribulbar anesthesiaas for inducing optimal operating conditions for eye surgery in terms of akinesia (as a primary end point), analgesia, incidence of complications, as well as patient and surgeon satisfaction (as secondary end points). Patients and Methods: The present study included 50 patients (females and males) aged 20-80 years. Materials: Anesthetic drugs, Needles size: 25 gauge, Intravenous cannula 22 G, Drugs for premedications: intravenous midazolam (5mg/ml, Mediathetic, Amoun, Egypt) (0.01mg/kg) and Fentanyl Citrate (50µg/ml, Fentanyl- Janssen, Belgium) (25 µg)was administrated 5minutes before the block, Monitors for vital signs registration were done for each of the following: Electrocardiograph (ECG), non-invasive blood pressure (NIBP), heart rate (HR) and oxygen saturation (SpO2), respiratory rate (RR), Anesthetic machine, resuscitation equipment and drugs. Results: The current study was carried on 75 patients divided into Three equal groups: first group (control group), second group (dexmedtomedine group) and third group (magnesium sulphate group). All patients were scheduled for surgery. Conclusion: Addition of 50 mg of magnesium 10% or 15 mic of dexmedetomidine to local anesthetic mixture for peribulbar anesthesia in the operations of phacoemulsification of cataract and intraocular lens implantation accelerated onset of globe anesthesia, akinesia of the globe and the lid, prolonged the duration of globe akinesia, lid akinesia, time to 1st analgesic request, and enhanced the satisfaction of the patients and quality of the operative conditions.