Comparative Effect of Local Anesthesia with Lidocaine 2% Versus Topical Anesthesia on Cognitive Function in Ophthalmic Surgery

Background: Multiple clinical trials targeted the assessment of cognitive function following local versus general anesthesia in patients undergoing ophthalmic surgery, but no previous clinical trials have focused on the effect of topical anesthesia on cognitive function.

Objectives: This study aimed to compare the effect of local anesthesia with lidocaine 2% versus topical anesthesia with Oxybuprocaine (benoxinate hydrochloride 0.4%) on cognitive function in patients undergoing elective cataract surgery.

Methods: This is a prospective randomized clinical trial carried out on 60 patients undergoing elective cataract surgery by phacoemulsification. Thirty patients received local anesthesia with lidocaine 2% and thirty patients received topical anesthesia with Oxybuprocaine (benoxinate hydrochloride 0.4%). Patients' satisfaction was assessed postoperatively using the Iowa satisfaction with anesthesia scale (ISAS). Cognitive assessment for all patients was done preoperatively and 1 week postoperatively using paired-associate learning test (PALT) and category verbal fluency (VF) test (animal category).

Results: There was no statistically significant difference between local and topical anesthesia groups in the mean of responses to the 11 statements of ISAS (P = 0.071). Regarding cognitive assessment, there was a statistically significant postoperative decline in the local anesthesia group in both PALT scores (P = 0.005) and VF scores (P = 0.01). In the topical anesthesia group, there was no statistically significant difference between pre- and postoperative PALT scores (P = 0.326) or VF scores (P = 0.199).

Conclusions: Postoperative cognitive dysfunction following elective cataract surgeries under local anesthesia can be attributed to the effect of local anesthesia rather than the effect of surgery.