A Cochrane review included 7 studies with a total of 617 subjects with 742 eyes operated. Five studies used unpaired data, with a single eye operated on; two studies used paired data with both eyes operated on. Three unpaired studies showed that sub-Tenon anaesthesia provided better intra-operative pain relief than topical anaesthesia (pooled WMD 1.28, 95% CI 0.83 to 1.72). 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). Surgical satisfaction was rated excellent in 86% of operations in the sub-Tenon group versus 67% in the topical group. Patient satisfaction with sub-Tenon anaesthesia was better than topical with median scores of 2.77 (inter quartile range (IQR) 2.45 to 3) versus 2.04 (IQR 1.54 to 2.5) (P = 0.008) on the Iowa Satisfaction with Anaesthesia Scale. Sub-Tenon anaesthesia caused slightly more pain during adminstration, 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%).
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment).