Methodological quality of the review: Low confidence

Author: Ye Z, Li Z, He S.

Region: Hungary, Germany, Tasmania, Italy, Denmark, China.

Sector: Cataract surgery

Sub-sector: Risk factor

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:

Conventional phacoemulsification cataract surgery (CPCS) is the most common surgical treatment for cataract. CPCS is generally effective for cataract but may cause a few complications, such as elevated intraocular pressure and macular edema, probably due to the heat generated by ultrasound during the procedure. Femtosecond laser-assisted cataract surgery (FLACS), a new technology that was firstly introduced in 2008, has shown promising treatment outcomes. To date, many studies have attempted to compare the outcome and complications of FLACS and CPCS. Some studies have shown better visual acuity recovery and lower endothelial cell loss after FLACS when compared with CPCS, whereas others have detected no significant difference between the two technologies.

Objectives:

Compare the outcomes and postoperative complications between femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS)

Main findings:

A total of 10 trials were included in the analysis, including eight from European countries, one from China, and one from Tasmania. Authors note generation of the randomization sequence was adequate in four trials. Blinding design was described in none of the enrolled studies. One study had a high risk of selective reporting because the author did not report all the outcome data that were described in the protocol.

Authors report that refractive outcomes (MD = −0.21, 95% Confidence Interval (CI): −0.39~0.03, P = 0 02) were significantly improved after FLACS. Although corneal endothelial cell loss was not significantly reduced after FLACS, there was a trend towards lower corneal endothelial cell loss (mean difference (MD) = 197.82, 95% confidence interval (CI): 2.66~392.97, P = 0 05) after FLACS. Authors reported no significant difference in uncorrected distance visual acuity (UDVA) (MD = −0.01, 95% CI: −0.13~0.10, P = 0 80) or corrected distance visual acuity (CDVA) (MD = −0.03, 95% CI: 0.07~0.00, P = 0 09) between the two surgeries. Findings also showed that elevated intraocular pressure and macular edema were most commonly developed complications after cataract surgery, and the incidence of these complications associated with the two surgeries was similar.

Methodology: 

Studies meeting the following criteria were included in the meta-analysis: (1) studies designed as prospective studies; (2) cataract patients were divided into FLACS and CPCS groups; (3) at least one of the following outcomes was reported: corneal endothelial cell counts, central corneal thickness, UDVA, CDVA, and refractive outcomes. Only the study with the longest follow-up time was included if the data was used in several studies. In addition, non-original studies, including reviews, letters, and comments, were excluded.

PubMed, Embase, and Cochrane library, were systematically searched to identify eligible studies until September 2015. The search key words were used including “femtosecond” AND “phaco OR phacoemulsification OR phakoemulsification” AND “cataract.”

Two authors independently extracted data according to a predefined information sheet. The Cochrane risk assessments tool was used to evaluate the quality of studies, including random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other biases.

The pooled weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated to evaluate the differences between the two techniques. The potential heterogeneity across studies was evaluated by Cochran’s Q and I² statistics. The random effect model was used in case of significant heterogeneity. Otherwise, the fixed effect model was used. Sensitivity analysis was performed through omitting one study each time to evaluate the stability of the meta-analysis.

Applicability/external validity:

Authors report that this study provided evidence supporting higher treatment efficacy of FLACS based on refractive stability and corneal endothelial cell protection. However, further studies are needed to validate their findings.

Geographic focus:

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

Summary of quality assessment:

Overall low confidence was attributed in the conclusions about the effects of this study, as important limitations were identified. Although authors used appropriate methods to analyse findings of included studies, it is not clear from the review if authors used appropriate methods to screen studies for inclusion and authors did not conduct a thorough search of the literature to avoid publication bias.