AIM: To compare the effect of sub-Tenon anesthesia 3 mL and 5 mL lidocaine on intraocular pressure(IOP), analgesia and akinesia. Sub-Tenon's anaesthesia is a common regional technique for cataract surgery by phacoemulsification. As a volume-based block, IOP optimization along with analgesia and akinesia is a concern for successful surgical course.

METHODS: After obtaining ethics approval and informed consent of patients, 70 patients were randomly enrolled to the study to receive sub-Tenon's block with either 3 mL(Group I)or 5 mL(Group II)lidocaine. IOP was measured before the block. IOP, analgesia and akinesia were evaluated at 10min after the block. Complications such as chemosis and subconjunctival hemorrhage were also noted.

RESULTS: Two patients were excluded from the study due to the patients' request for sedation during block administration. Patients' characteristics such as age, weight, height, axial length, American Society of Anesthesiology(ASA)physical status were comparable in-group before and after block measurement and between groups. Akinesia and analgesia were significantly better in Group II in comparison to Group I. “No eye movement” was obtained in 13 patients(38.2%)in Group II whereas none of the patients had “no eye movement” in Group I. Eighteen(56.3%)patients had “no pain” and 14(43.7%)patients had “mild pain” in Group I whereas “No pain” in 28 patients(82.4%)and “mild pain” in 6 patients(17.6%)was observed in Group II. On the other hand, IOP revealed no statistically significant alteration in both groups before and 10min after the block(P<0.05). Complications were comparable between groups.

CONCLUSION: Sub-Tenon's anaesthesia either with 3 or 5 mL lidocaine had no effects on IOP; on the other hand, analgesia and akinesia were preferably better in patients who received 5 mL lidocaine for the block during cataract surgery by phacoemulsification.