Clinical efficacy of modified phacoemulsification in the treatment of high myopia with cataract: a systematic review and meta-analysis

Authors: Qi J, Yuan J, Zhou Y, Guo R, Zhang Y, Dai Q, Liu Y

Geographical coverage: Not reported

Sector: Biomedical

Sub-sector: Treatment

Equity focus: None

Study population: Patients who met the diagnostic criteria for high myopia with cataract and who had either received modified phacoemulsification (treatment group) or traditional phacoemulsification (control group).

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background: Phacoemulsification is an effective and less risky treatment for high myopia with cataract compared to conventional extracapsular or intracapsular cataract extraction. However, the incidence of pseudophakic retinal detachment (PPRD) within 10 years is a concern, with a risk about 10 times that of rhegmatogenous retinal detachment in the general population. Factors contributing to this risk include intraoperative vitreous loss, increasing axial length, and age. Modified phacoemulsification aims to enhance the efficacy of the original procedure and mitigate its adverse effects. While some clinical reports suggest its safety and efficacy in treating high myopia with cataract, there is no consensus, and its effectiveness and safety require comprehensive evaluation.

Objectives: To evaluate the clinical effect of modified phacoemulsification in the treatment of high myopia with cataract.

Main findings:

In summary, the review determined that modified phacoemulsification is safer and more effective in treating high myopia with cataract compared to the traditional method.

The meta-analysis included 12 articles and found that modified phacoemulsification was superior to traditional methods in treating high myopia with cataract. This superiority was evident in lower postoperative complication rates, better visual acuity recovery one month post-surgery, and higher corneal endothelial cell counts at one and three months post-surgery. Despite both methods being effective, modified phacoemulsification showed greater benefits in reducing corneal endothelial cell damage, decreasing postoperative complications, and improving patient prognosis. The results suggest a high clinical value for modified phacoemulsification.

Review authors found a small possibility of publication bias in the included articles. The results of sensitivity analysis showed that the pooled effect size was still of statistical significance, and there were no significant changes in the direction of forest plots before and after removal.

The meta-analysis showed that modified phacoemulsification could effectively improve the corneal endothelial cell count of patients at different stages, reduce postoperative complications, and improve visual acuity. Collectively, this surgical method is safe and effective, and is worthy of clinical application.

Due to the limitation of the number and quality of included studies, the above conclusions still need to be verified via more high-quality studies.

Methodology:

The review included patients diagnosed with high myopia and cataract. The control group underwent traditional phacoemulsification, involving lens nucleus fragmentation, suction of fragments, and a 5.5 mm lamellar scleral incision for rigid intraocular lens implantation. The treatment group underwent modified phacoemulsification, which involved a 3.00 mm corneal incision, circular capsulorhexis, nucleus chopping with adjusted ultrasonic phacoemulsifier settings, and intraocular lens implantation after cortex aspiration. Outcome measures included postoperative complication rate, visual acuity recovery rate one month post-surgery, and corneal endothelial cell count at pre-surgery, one month post-surgery, and three months post-surgery. The review only included randomised controlled trials. Exclusion criteria were studies with unavailable data or original text, poor quality or duplicate literature, and non-cataract related literature, case reports, systematic reviews, and animal experiments.

Authors searched PubMed, Web of Science, EMBASE, China National Knowledge Infrastructure (CNKI), and Wanfang for relevant English and Chinese studies published from January 2010 to May 2021. The search terms used were: “modified phacoemulsification” and “high myopia” and “cataract”.

Literature screening was completed by two investigators independently according to screening criteria. During data extraction, disagreements between the two investigators were resolved by referring to the original literature and subsequent discussion with each other.

The software Review Manager 5.3 was utilised for statistical analysis, and dichotomous variables were compared using weighted mean difference (WMD) and OR, respectively. Assessment of heterogeneity was completed using the Q test and I² statistic. In the case of significant heterogeneity (I² >50%), the random-effects model was adopted; otherwise, the fixed-effects model was employed. Sensitivity analysis and publication bias assessment were also performed in this study using Stata.

Applicability/external validity: Authors indicate that quality of randomised controlled trails included generates a need for further high-quality studies (although little information is provided about quality concerns in practice).

Geographic focus:

The authors did not limit their search geographically, but they did not provide information on the countries of origin of the included studies. However, considering the inclusion of Chinese studies, it is probable that many were published in China.

Summary of quality assessment:

The methodologies used to select, include, and critically evaluate studies had certain limitations. Although two researchers conducted the key stages, there were no efforts to incorporate unpublished materials, scrutinise the reference lists of the included articles, or include publications outside of those in Chinese or English. While there is a brief mention of the risk of bias in the included studies, no comprehensive information is provided on this aspect. The data analysis approach was generally solid, but the authors did not account for the implications of including studies of varying quality and did not address the issue of unit of analysis errors related to randomised controlled trails. Due to these reasons, we attributed low confidence to the review’s findings