In this prospective randomized and double blind clinical study, involving 80 patients with ages from 30 to 86 years old, ASA I and II, both genders. The patients were randomly divided into 4 groups of 20 patients, and then were administered in control sub-Tenon's group 5 mL of 2% lidocaine with 1 mL of 0.9% sodium chloride solution; in sub-Tenon's group clonidine, 5 mL of 2% lidocaine associated with 1 µg/kg of clonidine diluted in 1 mL 0.9% sodium chloride solution. In the peribulbar anesthesia, the control group with 6 mL of 2% lidocaine and 1 mL of 0.9% sodium chloride solution, and peribulbar group clonidine, 6 mL of 2% lidocaine associated with 1 µg/kg of clonidine diluted in 1 mL 0.9% sodium chloride solution. Were evaluated the systemic hemodynamic variables; IOP and OPA measurements according the dynamic contour tonometer (DCT) and calculation of OPP, prior to the blockade (M0), and one (M1), five (5) and ten minutes (M10) after the injection of the anesthetic solutions. Complications related to the sub-Tenon's and peribulbar anesthesia were recorded.