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

Davison M, Padroni S, Bunce C, Rüschen H

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Summary

Sub-Tenon's anaesthesia versus topical anaesthesia for pain control and better operating conditions for cataract surgery

Cataract is the commonest cause of blindness worldwide; it is usually due to the normal ageing process. Cataract is the loss of the natural transparency of the lens of the eye. A cataract is treated by surgery to remove the lens and replace it with an artificial one. Cataract surgery is usually performed under local anaesthetic. There is debate as to which form provides better pain relief and operating conditions for the surgery.

Topical anaesthesia is performed by placing drops or gel of local anaesthetics on the surface of the eye. During the operation this may be supplemented by using a blunt needle to inject local anaesthetic to the front part of the eye through the operation incision (intracameral). Sub-Tenon anaesthesia is performed by first numbing the surface of the eye with local anaesthetic drops. The patient is then asked to look up and out. The membrane lining the front of the eye is held with blunt tweezers and a small nick is made in it with curved blunt-ended scissors. A small blunt sub-Tenon cannula is passed through this hole, round towards the back of the eye and alongside the globe to inject local anaesthetic in the sub-Tenon space.

This review was based on seven studies involving 617 patients.

The review showed that sub-Tenon anaesthesia provided better pain relief than topical anaesthesia during an operation for cataract surgery. The administration of topical anaesthesia was slightly less painful than sub-Tenon. Surgeons and patients both preferred sub-Tenon anaesthesia and there were more serious complications with topical than for sub-Tenon anaesthesia, although sub-Tenon anaesthesia tended to cause more minor, aesthetic problems. There was no report of any life threatening complications in any of the studies. Five of the seven studies used weak clinical methods.

This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2010 Issue 1, Copyright © 2010 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).
This record should be cited as: Davison M, Padroni S, Bunce C, Rüschen H. Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery. Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD006291. DOI: 10.1002/14651858.CD006291.pub2.

This version first published online: July 18. 2007

Abstract

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 (The 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.

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