Comparison of efficacy between coaxial microincision and standard-incision phacoemulsification in patients with age-related cataracts: a meta-analysis

Methodological quality of the review: Medium confidence

Author: Wang L, Xiao X, Zhao L, Zhang Y, Wang J, Zhou A, Wang J, Wu Q.

Region: China, Turkey and Japan

Sector: Age-related cataract

Sub-sector: Incisions

Type of cataract: Age-related cataract

Equity focus: None specified

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:

The choice of surgical incision plays a crucial role in the efficacy of surgery, as the incision damages the surrounding tissues and affects the surgical approach. The size of microincisional phacoemulsification surgery (MICS) incisions ranges from 1.8 mm to 2.2mm, whereas standard-incision phacoemulsification surgery (SICS) incisions range from 2.8 mm to 3.2mm. Research results on the comparative efficacy of MICS and SICS in patients with age-related cataracts are inconsistent, while some scholars suggest that MICS can effectively reduce surgically induced astigmatism (SIA) in both the short term and the long term compared with SICS, other studies indicate no significant difference between MICS and SICS.

Research objectives:

Examine the advantages and disadvantages by comparing the efficacy of MICS and SICS.

Main findings:

In total, authors included 11 randomized controlled trials (RCTs) in the meta-analysis. These included a total of 550 eyes in the MICS arms and 548 eyes in the SICS arms. Nine included studies were conducted in China and one each was conducted in Japan and Turkey. In terms of quality assessment, authors note that sequence generation was appropriate in five studies. One study was assessed a high risk on sequence generation as the random allocation was carried out according to registration order. Allocation concealment was described in three studies, but it was unclear in the other studies. The outcomes involved in this meta-analysis were objective, which contributed to the low risk of bias associated with blinding of participants and personnel and blinding of outcome assessments. The outcomes data were complete in two studies, and other studies were unclear. Two studies avoided selective reporting, and others were unclear.

No statistically significant differences were observed in elapsed phaco time (EPT) (Z = 1.29, P > 0.05), central corneal thickness (CCT) (1 day: Z = 1.37, P > 0.05; 7 days: Z = 0.75, P > 0.05; 30 days: Z = 0.38, P > 0.05; 90 days: Z = 0.29, P > 0.05), endothelial cell count (ECC) (7 days: Z = 1.13, P > 0.05; 30 days: Z = 1.42, P > 0.05) or ECC Loss % (7 days: Z = 0.24, P > 0.05; 30 days: Z = 0.06, P > 0.05; 90 days: Z = 0.10, P > 0.05) between MICS and SICS. However, statistically significant differences were found in average ultrasonic energy (AVE) (Z = 4.19, P < 0.0001) and SIA (1 day: Z = 10.33, P < 0.00001; 7 days: Z = 10.71, P < 0.00001; 30 days: Z = 10.95, P < 0.00001; 90 days: Z = 2.21,- P < 0.01) between MICS and SICS. Authors reported that publication bias had no influence on the credibility of their findings.

Based on these findings authors conclude that compared with SICS, MICS can reduce short-term and long-term SIA, but it does not differ in safety outcomes or in the time required for surgery.

Methodology

Authors included RCTs of patients with age-related cataract. Interventions included MICS versus SICS, studies with no difference in the surgical process between both incisions, apart from the difference in incision size. Outcome measures included surgically induced astigmatism (SIA). Secondary outcome measures included effective phacoemulsification time (EPT) and the average ultrasonic energy (AVE), central corneal thickness (CCT), endothelial cell count (ECC), and incidence of intraoperative and postoperative complications.

Authors searched the Cochrane Library (Wiley Online Library, 1999), PubMed, Medline, National Knowledge Infrastructure (CNKI), and VIP electronic databases. The databases were searched in October 2015 and an update was finished at January 2016 without restricting the publication status, year, language, or methodology. As part of the search strategy, authors also reviewed references of included studies. Screening of studies were conducted by two reviewers independently. The Cochrane risk and bias assessment tool was used to assess quality of included trials, which was conducted by two reviewers.

Applicability/external validity

Authors note that this study is representative, as it involves studies conducted in several regions, and outcomes of SIA, EPT, AVE, CCT, ECC, ECC Loss %, intraoperative complications, and postoperative complications were selected to evaluate the effects of surgery. All selected outcomes are objective, and the risk of bias was low for all outcomes.

Geographic focus

Authors did not specifically discuss findings applicability to low- and middle-income countries.

Quality assessment

Medium confidence was attributed in the conclusions about the effects of this study. Overall, authors used appropriate methods to analyse findings, screen studies for inclusion assess methodological quality of included studies. However, it is not clear if authors used reliable methods to extract data of included studies. Authors appropriately address limitations of the review.