Synthesis of the literature on the effectiveness of regional anaesthesia for cataract surgery

Methodological quality of the review: Medium confidence

Author: Friedman DS, Bass EB, Lubomski LH, Fleisher LA, Kempen JH, Magaziner J, Sprintz M, Robinson K, Schein OD.

Region: Details not provided

Sector: Cataract surgery

Sub-sector: Anaesthesia, regional anaesthesia.

Type of cataract: Age-related cataract

Equity focus: None Specified

Review type: Effectiveness review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not Applicable

Background

Local anaesthetic for cataract surgery is either administered through an injection or through the use of topical drops. Authors note that there is so far no consensus on what anaesthesia treatment is most effective for cataract surgery, especially in terms of intraoperative pain. Therefore the type of anaesthesia administered is down to surgeon preference.

Research objectives

‘To synthesize the findings of the randomized trials of regional anaesthesia management strategies for cataract surgery and determine the effectiveness of different forms of regional anaesthesia.’

Main findings

The systematic review included 82 randomized controlled trials (RCTs) assessing the effectiveness of different forms of anaesthesia. The review did not detail from which countries the trials originate. Authors reported the following results:

Current methods to administer anaesthesia provided adequate pain control although variation in effectiveness between the different types of anaesthesia existed. There was robust evidence taken from seven studies indicating that retrobulbar and peribulbar blocks provide equivalent akinesia pain control. There was good evidence that sub-Tenon’s blocks were at least as effective as retrobulbar and peribulbar blocks in pain control were also less painful on administration. There was good evidence that retrobulbar block provides better pain control than topical anaesthesia and fair evidence that peribulbar block provides better pain control than topical anaesthesia, although topical anaesthesia is less painful on administration.

In terms of study design, authors noted that the review concentrated largely on intraoperative pain control to determine the effectiveness of different types of anaesthesia but recognized that intraoperative pain control is not the only factor that should be considered. Other considerations should include patient anxiety, patient preferences for complications or side effects that may differ between anaesthesia options, level of discomfort on administration, need for supplemental intravenous injection and cost.  Authors suggest that future research should investigate these issues and include patient preferences on issues such as anxiety, drowsiness and nausea.

Methodology

The authors included randomized control trials that specifically compared 1) the ability of different block techniques to produce akinesia, 2) the pain perceived by patients during the administration of regional anaesthesia, 3) the level of pain control produced by different regional anaesthesia approaches and 4) the complications associated with different approaches to regional anaesthesia.

The authors conducted a systematic search of literature on PUBMED and CENTRAL as well as a hand search of 10 ophthalmology and anaesthesia related journals (1964-1999). It was noted that a full description of the search strategies was published in a companion article and is available from the Agency for Healthcare, Research and Quality (AHRQ) and posted online. Authors used an evidence grading system from Garbutt et al to measure the strength of evidence of studies included in the review. This system measured adequacy of sample size, consistency of data, and accurate description of the intervention. Two authors independently screened full text articles for eligibility and extracted data of included studies.

Due to the heterogeneity of the included trials in terms of aims, content and design and outcomes measures, it was not possible to conduct a meta-analysis. Instead authors used a grading system in order to grade the strength of the evidence provided.

Applicability/external validity

The authors did not discuss in detail the applicability/external validity of the results. However, in relation to patient-reported pain, although the literature supported the effectiveness of topical anaesthesia, many of these studies were conducted by ‘higher volume cataract surgeons with short operating times’ and therefore results may not be applicable to all surgeons.

Geographic focus

Authors did not provide the geographical location of included studies.

Quality assessment

Authors noted on the review that a full description of the search strategies is published in a companion article which was posted online and available from the Agency for Healthcare, Research and Quality (AHRQ). Unfortunately, this was not available in this assessment (10/11/14). Therefore, it should be noted that quality assessment is based on the information provided in this review only.

This systematic review was based on a partially comprehensive search of the literature, and although it covered relevant databases and reference lists of included studies, authors/experts were not contacted for potentially relevant studies, and articles were restricted to published articles written in English. Authors measured adequacy of sample size, consistency of data, and accurate description of the intervention but in the main review they did not report other risk of bias indicators such as performance, attrition, detection bias etc.

Methods used to analyse the findings were clear and due to the heterogeneity between the included studies, a narrative synthesis was appropriate. Authors recognized that a major limitation to the review in its findings was that most studies included did not report on surgical time, which was problematic when the length of surgery and the effectiveness of anaesthesia as reported by patients are likely to be correlated. Therefore, medium confidence in the conclusions about the effects was attributed to this review. Information regarding the quality of the randomized trials included in the study is crucial to determine the reliability of the results, as well as a full description of the search strategy.