Efficacy of Capsular Tension Ring Implantation in the Treatment of High Myopia Cataracts: Meta-Analysis

Author: Li X, Zeng W, Tan Q, Lan C, Liao X.

Geographical coverage: Not reported

Sector: Cataracts extraction

Sub‑sector: Intraocular lens

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis: Meta‑analysis

Qualitative synthesis: Not applicable

Background:

During cataract surgery, capsular tension rings (CTRs) provide structural support to the lens capsule and help to tabiliza intra‑ocular lens (IOL) placement. CTRs were first used clinically in the 1990s and are increasingly deployed in cases of high‑myopia cataract, where weak zonular fibres, thin posterior capsules and loose lens structures make surgery more difficult. These anatomical challenges increase the risk of complications such as rupture of the posterior capsule, zonular dialysis and postoperative problems including posterior capsular opacification (PCO), capsular contraction syndrome (CCS) and retinal detachment (RD). CTRs offer mechanical tabilization that reduces IOL decentration, posterior capsule folds and the incidence of such complications. Although multiple clinical studies have investigated the use of CTRs in high‑myopia cataracts, their results remain inconsistent. A comprehensive evaluation is therefore needed to assess whether CTRs improve surgical safety and visual outcomes.

Objective:

To evaluate the effectiveness of phacoemulsification cataract extraction with intra‑ocular lens and capsular tension ring implantation in patients with high‑myopia cataracts.

Main findings:

The review included eight studies comprising 1 200 eyes. Six were randomised controlled trials, one was a non‑randomised controlled trial and one was a cohort study. All the included studies were deemed high‑quality clinical research.

The meta‑analysis found no statistically significant differences in best‑corrected visual acuity (BCVA) between the experimental and control groups at one week, one month and three months post‑operatively (P > 0.05). However, BCVA in the experimental group was significantly higher at six months post‑operatively (mean difference 0.12, 95 % confidence interval [CI] 0.08–0.16, P < 0.00001). The incidences of PCO, CCS and RD were lower in the experimental group, with statistically significant differences (odds ratio [OR] 0.45, 95 % CI 0.30–0.68, P < 0.00001; OR 0.35, 95 % CI 0.20–0.60, P < 0.00001; OR 0.25, 95 % CI 0.15–0.40, P < 0.00001 respectively).

Methodology:

Searches were conducted in several databases, including PubMed, Embase, the Cochrane Library and the Chinese databases CNKI, Wanfang Data and the VIP database, up to December 2020. Studies published in English or Chinese involving patients with pre‑operative myopia of −6.00 D or axial length ≥ 26.0 mm were eligible. The review compared phacoemulsification surgery with combined IOL and CTR implantation against phacoemulsification with IOL implantation alone. Reference lists of included studies and previously published articles were also scanned for additional relevant publications.

Two researchers independently extracted data and resolved discrepancies through discussion with a third researcher. The quality of the randomised controlled trials was assessed using the Cochrane Handbook quality assessment tool, and the quality of the non‑randomised studies using the Newcastle–Ottawa scale. Findings were synthesised using fixed‑ or random‑effects meta‑analysis. Heterogeneity was assessed using the chi‑squared test and I² statistics, and publication bias was examined using a funnel plot and Egger’s asymmetry test. Sensitivity and subgroup analyses were undertaken to explore possible sources of heterogeneity.

Applicability and external validity:

The review did not explicitly discuss the applicability or external validity of its findings. It acknowledged a risk of bias due to the inclusion of non‑randomised studies and noted that the included studies did not consider capsule‑bag complex dislocation because of limited follow‑up. The authors also highlighted that patient age was omitted as a variable, which may influence outcomes, and called for future high‑quality studies with stricter designs to reduce bias and strengthen evidence‑based recommendations.

Geographical focus:

The review applied no geographical limits but did not report on the geographical distribution of the included studies.

Summary of quality assessment:

Overall, confidence in the conclusions is low. The searches were comprehensive; inclusion and exclusion criteria were clearly defined; and two reviewers independently extracted data and assessed study quality using established tools, resolving disagreements through discussion or consultation with a third reviewer. Characteristics of included studies were well documented, meta-analyses were appropriately performed, and heterogeneity was addressed. However, the search was limited to articles published in English and Chinese. The review did not provide a list of excluded studies or specify the number of reviewers involved in screening.