Methodological quality of the review: Low confidence

Author: Wang J, Su F, Wang Y, Chen Y, Chen Q, Li F.

Region: Not reported

Sector: Biomedical

Subsector: Treatment

Equity focus: Not stated

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:
In this modern developing society, the total number of people undergoing eye surgery is gradually increasing. Agarwal’s et al. recent study based on current and effective features of femtosecond laser-assisted cataract surgery (FLACS) showed that surgeons might now be more confident and patients might be more satisfied with FLACS, however, a few studies showed that this surgery was not a better option when compared to the manual phacoemulsification in terms of outcomes and complications.

Objectives:
To compare the complications which were associated with femtosecond laser-assisted cataract surgery (FLACS) versus the conventional phacoemulsification surgery (CPE).

Main findings:
Authors included eight prospective studies (randomised and non-randomised) in this review, including 7,156 participants. Of these, 3,554 were assigned to the FLACS group and 3,602 were assigned to the CPE group.

The risks for incomplete capsulotomy, anterior capsulotomy tag and anterior capsular tear were significantly higher with FLACS (RR: 22.42, 95% CI: 4.53–110.82; P=0.0001), (RR:33.07, 95% CI: 6.53–167.56; P=0.0001) and (RR: 4.74, 95% CI: 2.59–8.68; P=0.00001), respectively. The risks for macular/corneal edema (RR: 2.05, 95% CI: 1.18–3.55; P=0.01) and elevated intra-ocular pressure (RR: 3.24, 95% CI:1.55–6.78; P=0.002) were also significantly higher with FLACS. However, the risks for impaired Descemet’s membrane (RR: 0.95, 95% CI: 0.61–1.47; P=0.80), zonular dialysis (RR: 0.40, 95% CI: 0.06–2.72; P=0.35), vitreous loss (RR: 0.09, 95% CI: 0.01–1.63; P=0.10) and posterior capsular tear (RR: 1.45, 95% CI: 0.23–9.16; P=0.69) were not significantly different.

Based on the statistical analyses, authors conclude that FLACS did not improve intra/post-operative complications in comparison to CPE. Further larger studies should confirm this hypothesis.

Methodology:
Commonly used search databases, specifically MEDLINE, Cochrane Central, Embase, and ClinicalTrials.gov, were carefully searched for English publications comparing FLACS versus CPE. Reference lists of several relevant publications were also carefully reviewed.

Studies were included if they compared the complications (intra/peri/post-operative) associated with FLACS versus CPE. Primary outcome measured in this study included incomplete capsulotomy, anterior capsulotomy tag, anterior capsule tear, posterior capsule tear, Descemet’s membrane impairment, zonular dialysis, vitreous loss, macular or corneal edema and elevated intra-ocular pressure.

Data extraction of included studies were conducted by six reviewers independently. Methodological quality of studies was assessed using the Newcastle-Ottawa Scale (NOS).

Statistical analysis was conducted using RevMan software. Risk ratios (RRs) with 95% confidence intervals (CIs) were used to represent the data following statistical analysis. During this analysis, heterogeneity was assessed first of all by the Q statistic test, whereby a subgroup analytical result with a P value less or equal to 0.05 was considered as statistically significant and a result with a P value greater than 0.05 was considered statistically insignificant. In addition, heterogeneity was also assessed by the I² test. A fixed statistical effect model was used if the I² value was less than 50% or else, a random statistical effect model was used. Sensitivity analysis was also carried out following the statistical. In addition, publication bias was assessed through visual observation of the funnel plots.

Applicability/external validity:
In this current analysis, authors compared the intra and postoperative complications which were associated with FLACS versus CPE. The results showed no improvement in complications with the former.

Geographic focus:
Geographic focus of studies included in the review which were not reported.

Summary of quality assessment:
Low confidence was attributed to the conclusions about the effects of this study, as important limitations were identified. Literature searches were not comprehensive enough to ensure that all relevant studies were identified, therefore impacting on the validity of findings. It is not clear if methods used to screen studies for inclusion were rigorous in ensuring that bias was avoided. In addition, the review does not make it clear which evidence is subject to low risk of bias in assessing causality.