Methodological quality of the review: High confidence

Author: Alhassan MB, Kyari F, Ejere HO.

Region: Finland, Canada, United States of America (USA) and India

Sector: Cataract surgery

Sub-sector: Local anaesthesia, peribulbar anaesthesia, retrobulbar anaesthesia.

Type of cataract: Age-related cataract

Equity focus: None specified

Review Type: Effectiveness Review

Quantitative synthesis method: Descriptive narrative of results and meta-analysis

Qualitative synthesis methods: Not applicable

Background

Unless medically contraindicated, cataract surgery is usually performed under local regional anaesthesia. Local anaesthesia involves the blockage of a nerve subserving a given part of the body. It involves infiltration of the area around the nerve with local anaesthetic. The two main approaches in the eye are retrobulbar and peribulbar. There is debate over whether the peribulbar approach provides more effective, safer anaesthesia for cataract surgery than retrobulbar block.

Research objectives

To assess the effects of peribulbar anaesthesia (PB) compared to retrobulbar anaesthesia (RB) on pain scores, ocular akinesia, patient acceptability and ocular and systemic complications.

Main findings

Authors included six randomized control trials (RCTs) in the review, comparing peribulbar anaesthesia and retrobulbar anaesthesia for cataract surgery. Of the studies included, two were conducted in Finland, two in USA, one in Canada and one in India. The authors reported the following findings:

There was no evidence of any difference in pain perception during surgery with either retrobulbar or peribulbar anaesthesia. Both were largely effective. There was no evidence of any difference in complete akinesia or the need for further injections of local anaesthetic. Conjunctival chemosis was more common after peribulbar block (relative risk (RR) 2.11, 95% confidence interval (CI) 1.46 to 3.05) and lid haematoma was more common after retrobulbar block (RR 0.36, 95% CI 0.15 to 0.88).

Retrobulbar haemorrhage was uncommon and occurred only once, in a patient who had a retrobulbar block.

As such, authors concluded that there is no significant difference between peribulbar and retrobulbar anaesthesia in terms of pain perception, effectiveness and akinesia. Moreover, authors note that there is a need to examine methodologies used in research on local anaesthesia, making sure that outcome measures are assessed quantitatively and not qualitatively.

Methodology

The authors conducted a search of literature on various databases including CENTRAL MEDLINE and EMBASE and did not impose date or language restrictions. As part of the search strategy, reference lists were also searched for additional trials, and primary investigators of identified trial were contacted for information on additional trials.

Two authors independently screened the titles and abstracts from the searches and assessed the quality of included studies. Methodological quality was assessed using the Cochrane approach. Thereafter, data was extracted into a form developed specifically for the review by two authors independently.

Authors included RCTs comparing peribulbar anaesthesia and retrobulbar anaesthesia for cataract surgery. Primary outcome measures included: (1) Pain experienced during surgery, (2) Ocular akinesia, and (3) Acceptability of block to patients.

Secondary outcomes included (1) Need for supplemental injection, and (2) Complications of the procedure as reported by the primary investigators, including local and systemic complications.

Authors conducted a descriptive narrative of results as the included studies used varied methods for reporting the outcomes and a sub-group analysis for globe akinesia. Data synthesis included on a summary of statistics, heterogeneity analysis and sensitivity analysis.

Applicability/external validity

The review does not clearly discuss how generalizable the results are and does not illustrate methods to assess applicability.

Geographic focus

The review included studies from both high- and middle-income settings, but with no specific emphasis on research implications for low- to middle-income settings.

Quality assessment

The systematic review was based on a comprehensive search of relevant databases including CENTRAL, MEDLINE, and EMBASE. No date or language restrictions were imposed on the search and reference lists from the included articles were searched. Appropriate methods were used by the reviewers to reduce risk of bias in terms of study selection, data extraction and analysis.

The likelihood of bias within the included studies was addressed and authors noted that the strength of evidence in the review in regards to pain score, akinesia and need for additional injection was low due to the poor methodological quality of the included studies. Therefore, high confidence was attributed in the conclusions about the effects of this review.