Randomized double-blind clinical trial comparing topical and sub-Tenon's anaesthesia in routine cataract surgery

Background. Several local anaesthetic techniques are availablefor cataract surgery. Recently, topical anaesthesia has gainedin popularity. A randomized trial was designed to compare patientdiscomfort and intraoperative complications following routinecataract surgery under topical or sub-Tenon's anaesthesia. Methods. A randomized double-blinded placebo-controlled clinicaltrial of 210 patients assigned to either a sub-Tenon's group(sub-Tenon's anaesthesia with placebo topical balanced saltsolution, n=140) or a topical anaesthesia group (topical anaesthesiawith placebo sub-Tenon's injection of balanced salt solution,n=70) was carried out. All patients underwent phacoemulsificationwith intraocular lens implantation. Patients in the sub-Tenon'sgroup received a single injection (3 ml) of a combination oflidocaine 2% (2 ml) and bupivacaine 0.75% (1 ml), and four dosesof topical placebo (balanced salt solution). Patients in thetopical anaesthesia group received four doses of topical proxymethocaine0.5% and a placebo sub-Tenon's injection (3 ml) of balancedsalt solution. No intracameral injection of local anaestheticwas given. A 10-point visual analogue pain scale was used preoperativelyand for postoperative pain assessment immediately after theoperation and 30 min postoperatively. The intraoperative complicationsin the two groups were recorded. Results. The mean pain score immediately after surgery was 2.42(SD 2.2) in the sub-Tenon's group and 3.44 (2.3) in the topicalanaesthesia group (P=0.0043). The mean pain score 30 min aftersurgery was 1.24 (1.7) in the sub-Tenon's group and 2.25 (2.2)in the topical anaesthesia group (P=0.0009). Conclusions. Patients undergoing cataract surgery under topicalanaesthesia experience more postoperative discomfort than patientsreceiving sub-Tenon's anaesthesia. Surgery-related complicationswere similar in both groups.