Most of the ophthalmic procedures are performed under local anesthesia as the patient is often elderly and with diseases. This may increase the risk of morbidity and mortality under general anesthesia. Different eye blocks have been practiced with great success. Moreover, it is associated with less hemodynamic instability, less respiratory depression, better postoperative pain relief, and less nausea and vomiting than general anesthesia. It is also associated with a reduction in stress response, maintained oxygen saturation and cardiovascular stability, in addition to the production of good akinesia and anesthesia alleviating occulo-medullary reflexes, all make local anesthesia more superior and safe technique.

Peribulbar anesthesia is widely practiced now as a safe local block for cataract eye surgeries. However, the limited duration of these blocks was shown to be the main problem encountered intra-operatively. Therefore, additional top-up doses are usually needed to continue the operation. Many kinds of research tried to introduce solutions in order to prolong the duration of the local anesthetics used. Many researchers tried different volumes, doses and adjuvant to local anesthetics, and studied their effects There are many studies that evaluated the effect of baricity of local anesthetic on the potency of motor block and the duration of motor and sensory blockade.

However, no properly designed randomized, controlled studies have evaluated the feasibility and reliability of baricity local anesthetic agents used for the peribulbar block.

Aim of the work prospective, randomized study was conducted to evaluate the effects of the baricitized bupivacaine used for the peribulbar block in patients undergoing posterior segment surgeries.

Inclusion Criteria:

• Patients with American Society of Anesthesiology (ASA) I or II.
• 30-80 years old
• Patients scheduled for elective unilateral posterior segment surgeries.

Exclusion Criteria:

• Patient's refusal.
• orbital deformity
• axial length( >28 mm )
• increased intraocular pressure, or if they were blind in the contralateral eye, international normalized ratio (INR) > 1.5
• allergy to local anesthetics, mentally retarded patients