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.