Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery

Background Local anaesthesia for cataract surgery can be provided by either sub-Tenon or topical anaesthesia. Although there is some work suggesting advantages to both techniques, there has been no recent systematic attempt to compare both techniques for all relevant outcomes. Objectives To compare the effectiveness of topical anaesthesia ( with or without the addition of intracameral local anaesthetic) and sub-Tenon's anaesthesia in providing pain relief during cataract surgery. Search strategy We searched the Cochrane Central Register of Controlled Trials ( T h e Cochrane Library, 2006, Issue 2); MEDLINE ( 1990 to July 2006); EMBASE ( 1990 to July 2006) and reference lists of articles. There were no constraints based on language or publication status. Selection criteria We included all randomized or quasi-randomized studies comparing sub-Tenon anaesthesia with topical anaesthesia for cataract surgery. Data collection and analysis Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We also collected adverse effects information from the trials. Main results Seven studies involving 617 patients with 742 eyes operated on were examined. Five studies used unpaired data, with a single eye operated on; two studies used paired data with both eyes operated on. The surgical technique was clear corneal incision in five studies and scleral tunnel in two. The overall quality of the studies was not high, with one study triple blind ( patient, surgeon and assessor blinded to treatment group) and three others single blind. The allocation of concealment and methods of randomization were only described in two studies. Three unpaired studies showed that sub-Tenon anaesthesia provided better intra-operative pain relief than topical anaesthesia ( pooled weighted mean difference ( fixed) 1.28, 95% CI 0.83 to 1.72). The differences in the pain scores are not necessarily clinically significant although statistically significant. The differences are not large in magnitude and are skewed to the low end of the visual analogue scale but the studies are consistent throughout in reporting more pain in the topical anaesthesia group. This was also supported by the one paired study which showed that the mean pain score in the topical group was 1.13 (SD 1.57) compared with 0.57 ( SD 1.28) in the sub-Tenon group ( P < 0.001). Three of the studies used a 10-point visual analogue scale, while one used a novel 5-point scale. Further support was provided by other outcome measures. Sub-Tenon anaesthesia caused more chemosis and sub-conjunctival haemorrhage although this was purely aesthetic. The more serious complication of posterior capsule tear and vitreous loss occurred twice as much in the topical group than with sub-Tenon anaesthesia (4.3% versus 2.1%). Authors' conclusions Sub-Tenon anaesthesia provides better pain relief than topical anaesthesia for cataract surgery.