Effect of Implanted Capsular Tension Ring on Postoperative Refractive Shift: A Systematic Review and Meta-Analysis.

Background: The capsular tension ring is a novel assistant tool for cataract surgery; however, controversy exists in its co-implantation. The potential for hyperopic or myopic shift resulting from the co-implantation of the capsular tension ring and intraocular lens remains unclear. This study aimed to determine the postoperative refractive prediction error and the direction of refractive shift in cataract patients who underwent capsular tension ring co-implantation.
Methods: We conducted a systematic review and meta-analysis,searching electronic databases for studies of individuals diagnosed with cataracts receiving surgery with or without capsular tension ring implantation. Systematic searches were performed based on five databases: PubMed, Cochrane Library, Web of Science, Medline, and China National Knowledge Infrastructure. The primary outcome was the mean arithmetic refractive prediction error. Secondary outcomes were mean absolute refractive prediction error and the number of eyes within a certain refractive prediction error range. We applied a fixed-effectsmodel to pool effect sizes across trials using weighted mean differences (WMD) and risk ratios (RR) with their 95% confidence intervals (95% CI). Statistical heterogeneity scores were assessed with the I ² statistic.
Results: A total of 407 affected eyes were included in eight independent clinical studies. Meta-analysis suggested significant differences both in short-term (≤1 month) co-implantation (WMD = 0.16, p  < .001, 95% CI: -0.13 ~ 0.19) and long-term (≥3 months) co-implantation between the capsular tension ring co-implantation group and the control group (WMD = 0.19, p  < .001, 95% CI: 0.15 ~ 0.23). However, no significant difference was observed in the high myopia subgroup whether capsular tension ring co-implantation (WMD = 0.03, p  = .083, 95% CI: -0.27 ~ 0.34). Heterogeneity was not found among the studies.
Conclusion: Compared to simple intraocular lens implantation, capsular tension ring co-implantation is more susceptible to developing hyperopic shifts in non-myopic cataract patients, probably related to anterior chamber depth. It requires careful consideration by clinicians when determining the target diopter preoperatively. However, interpretation is limited, because there is a lack of studies available for analysis. There still needs to be additional studies to expand the evidence base.