Methodological quality of the review: Medium confidence

Author: Guay J, Sales K

Region: Not reported

Sector: Cataract surgery

Sub-sector: Anaesthesia

Type of cataract: Age-related cataract

Equity focus: None specified

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:

Local anaesthesia for cataract surgery can be provided by sub-Tenon’s or topical anaesthesia. Topical anaesthesia is provided by placing local anaesthetic drops or gel of local anaesthetics on the surface of the eye. Sub-Tenon’s anaesthesia is provided by first numbing the surface of the eye with local anaesthetic drops, holding the tissue lining (conjunctiva and Tenon’s capsule) in front of the eye with blunt tweezers and making a small nick in it using curved blunt-ended scissors. Both techniques offer possible advantages. This review, which originally was published in 2007 and was updated in 2014, was undertaken to compare these two anaesthetic techniques.

Research objectives:

The objectives were to compare the effectiveness of topical anaesthesia (with or without intracameral local anaesthetic) versus sub- Tenon’s anaesthesia in providing pain relief during cataract surgery. Authors reviewed pain during administration of anaesthesia, postoperative pain, surgical satisfaction with operating conditions and patient satisfaction with pain relief provided, and looked at associated complications.

Main findings:

Authors included a total of eight studies in this updated version, but could only retain in the analysis seven studies on 742 operated eyes of 617 participants. Two cross-over trials included 125 participants, and five parallel trials included 492 participants. The mean age of participants varied from 71.5 years to 83.5 years. The female proportion of participants varied from 54% to 76%. Compared with sub-Tenon’s anaesthesia, topical anaesthesia (with or without intracameral injection) for cataract surgery increases intraoperative pain but decreases postoperative pain at 24 hours. The amplitude of the effect (equivalent to 1.1 on a score from 0 to 10 for intraoperative pain, and to 0.2 on the same scale for postoperative pain at 24 hours), although statistically significant, was probably too small to be of clinical relevance. The quality of the evidence was rated as high for intraoperative pain and moderate for pain at 24 hours. Authors did find differences in pain during administration of local anaesthetic (low level of evidence), and indications that surgeon satisfaction (low level of evidence) and participant satisfaction (moderate level of evidence) were less with topical anaesthesia. Authors note that there was not enough evidence to say that one technique would result in a higher or lower incidence of intraoperative complications compared with the other.

Authors concluded that both topical anaesthesia and sub-Tenon’s anaesthesia are accepted and safe methods of providing anaesthesia for cataract surgery. An acceptable degree of intraoperative discomfort has to be expected with either of these techniques. Randomized controlled trials on the effects of various strategies to prevent intraoperative pain during cataract surgery could prove useful.

Methodology:

Inclusion criteria for this review consisted of randomized control trials (RCTs) comparing topical anaesthesia with or without intracameral injection versus sub-Tenon’s anaesthesia. Authors only included studies performed on adult participants, who underwent operation in one or both eyes. Review authors include studies which compared sub-Tenon’s anaesthesia versus topical anaesthesia (eye drops or gel) with or without intracameral injection. Primary outcome measure included pain during surgery. Secondary outcomes included: 1) pain during administration of local anaesthetic; 2) postoperative pain at 30 minutes and at 24 hours; 3) Surgical satisfaction with operating conditions; 4) patient satisfaction with analgesia provided; and 5) complications that occurred as defined by study authors.

Authors conducted a search on Medline, CENTRAL and EMBASE. In addition, authors searched reference lists of identified studies and searched a range of websites to identify trials in progress. No restrictions were applied in terms of language and date. Authors reviewed the titles and abstracts identified by the searches and assessed full-text copies of potentially relevant studies and extracted data of included studies.

Authors extracted data of included studies and data were entered into RevMan. To assess trial quality, authors used the Cochrane tool.

To analyze the data authors conducted a meta-analysis and assessed heterogeneity before pooling results, using the I2 statistic. Authors also explored more specific comparisons with significant heterogeneity and explored heterogeneity by using Eggers’ regression intercept.

Applicability/external validity:

Authors note that results of the meta-analysis suggest that both techniques can be used for cataract surgery. However, authors report that on the basis of three included studies where the difference in intraoperative pain in favour of sub-tenon’s technique is too small to be of clinical relevance. They also emphasize that the review does include enough participants to exclude differences of intraoperative complications between the anesthetic techniques.

Geographic focus:

Authors did not report results specific to low- and middle-income countries.

Quality assessment:

Overall, there is medium confidence in the conclusions about the effects of this study. Authors conducted appropriate methods to analyze findings from this review and appropriately conducted analysis of included studies. However, it’s not clear if authors conducted screening of studies for inclusion and data extraction appropriately avoiding risk of bias.