Topical anaesthesia versus regional anaesthesia for cataract surgery: A meta-analysis of randomized control trials

Methodological quality of the review: Medium confidence

Author: Zhao L, Zhu H, Zhao P, Wu Q, Hu Y.

Region: Korea, Hungary, India, China, Europe and United States of America (USA).

Sector: Cataract surgery, anaesthesia

Sub-sector: Topical anaesthesia, regional anaesthesia.

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis methods: Not applicable

Background

Anaesthetic techniques used for cataract surgery include retrobulbar anaesthesia (RBA), peribulbar anaesthesia (PBA) and Topical Anaesthesia (TA). In studies that compare these different types of intervention in relation to Phacoemulsification (Phaco), conclusions about the outcomes, benefits and differences between the types of intervention are inconsistent.

Research objectives

To examine possible differences in the clinical outcomes of topical anaesthesia (TA) and regional anaesthesia including retrobulbar anaesthesia (RBA) and peribulbar anaesthesia (PBA) in Phaco.

Main findings

Fifteen randomized control trials were included in the review that compared TA and RBA/PBA in Phaco. Studies included were conducted in India, China, Korea, Europe and the USA.

The incidence of intraoperative pain was reported in 12 studies and data synthesis showed that there was an overall trend of more pain perceived by the patients receiving TA. Eight studies reported postoperative pain and dichotomized data showed that patients receiving TA perceived statistically significantly more pain. Five studies looked at inadvertent intraoperative eye movement, which was shown to occur more frequently in the TA group than RBA or PBA groups.

Six studies reported on intraoperative difficulties which showed no statistically significant differences between the two groups TA and RBA/PBA. Authors noted that due to the poor definitions of intraoperative difficulties in studies and heterogeneity of these six studies, these results should be interpreted with caution. Eight trials recorded the necessity to administer supplementary anaesthesia (regional injection) during Phaco and showed that the use of topical anaesthesia resulted in a significant trend for an increased need for supplementary anaesthesia. Authors noted that due to poor definitions and heterogeneity of the criteria for pain score management and the need for supplemental anaesthetic injection, these studies should be met with caution.

The authors concluded that topical anaesthesia did not achieve the same level of intraoperative pain relief as RBA/PBA, although it did achieve the same surgical outcomes. There is no statistically significant difference in intraoperative difficulties between the two groups. Topical anaesthesia, although less effective for pain relief, did reduce injection-related complications and alleviated patients’ fear of injection. They also noted that future research would be needed to investigate the risks posed by intraoperative eye movement and postoperative blinking related to topical anaesthesia; and more RCTs were needed to investigate the relationship between systemic sedation and regional anaesthesia in phacoemulsification.

Methodology

Authors included RCTs that compared TA and RBA/PBA in Phaco. Primary outcome measures included (1) measures of pain during and after the surgery, (2) measures of intraoperative difficulties and inadvertent eye movement (3) need for additional anaesthesia during surgery and (4) patient preference.

Authors conducted a review of the literature using PUBMED, EMBASE and the Cochrane Controlled Trails Register Databases for publications up to July 2010. There was no language restriction on the publication. Authors also manually searched the bibliographies of all potentially relevant articles for additional studies. Two authors independently searched the databases, appraised the quality and extracted data of selected studies; however, it was not clear if the two authors independently screened the abstracts and titles of searched articles for inclusion.

Authors conducted a meta-analysis and results showing significant heterogeneity were subject to a random effects model. Data from studies which were presented as continuous outcome data were converted into dichotomous data by dividing into two groups and were assessed on an intention-to-treat basis. A P-value of less than 0.05 was considered statistically significant.

Applicability/external validity

The authors did not discuss how generalizable the results were.

Geographic focus

The review did not specifically focus on low- and middle-income countries or discuss how the results are applicable to this setting.  The review included studies conducted in India, China, Korea, Europe and the USA.

Quality assessment

Authors conducted a search of databases including PUBMED, EMBASE and Cochrane Controlled Trials Register for publications up to July 2010. Nevertheless, it was noted that the review itself was not published until 2012. Although language bias was avoided within the review, selection bias was not. It was not clear whether authors/experts were contacted for further information/data as part of the search strategy.

Overall, the method used to select studies, analyse findings and appraise included studies were appropriately conducted and clearly reported by the authors. It should be noted that authors transformed continuous outcome data into dichotomous outcome data for some outcome measures – deciding on a cut-point may have been  arbitrary and information may have been lost when transforming data. Nevertheless, authors did note that due to the poor definitions of intraoperative difficulties and pain score management, some of these results should be interpreted with caution. Thus, medium confidence in the conclusions about the effects was attributed to this review.