Treatment effect of posterior scleral reinforcement on controlling myopia progression: A systematic review and meta-analysis

Methodological quality of the review: Medium confidence

Author: Chih-An Chen, Pao-Yen Lin, Pei-Chang Wu

Region: USA, China

Sector: Myopia

Subsector: Myopia treatment

Equity focus: No

Study population: All ages

Type of programme: Clinical based

Review type: Other review

Quantitative synthesis method: Systematic review and meta-analysis

Qualitative synthesis method: Not applicable

Background: Pathologic myopia is one of the major causes of blindness worldwide. It is an important and sight-threatening disease that causes scleral thinning, axial elongation, localised posterior scleral ectasia, and eventually many severe complications, such as retinal detachment, myopic choroidal neovascularisation, macular schisis, and macular hole and macular degeneration. For controlling myopia progression, posterior scleral reinforcement (PSR) surgery was first described by Shevelev in 1930, and was modified as the Snyder-Thompson method in 1972, which is the most commonly performed operation currently. To date, the therapeutic benefits of PSR remain controversial, due to a lack of controlled studies investigating the effectiveness. To the best of our knowledge, no systematic review study confirmed or quantitatively defined the treatment effect of PSR operation.

Objectives: The objective of this review was to explore the treatment effect and complications of posterior scleral reinforcement in the treatment of myopia.

Main findings: A total of 11 articles met the criteria for inclusion in this meta-analysis. The operation methods were single wide strip (n=9) and X-type PSR (n=2). Among these studies, six were self-control studies using the fellow eye as controls, and five studies compared PSR versus a control group without PSR treatment. On estimating the treatment effect, the mean differences of myopia progression and axial length changes between surgery and control groups were 0.41 diopters per year (95% CI 0.21 to 0.61; P<.001) and -0.17 mm per year (95% CI -0.22 to -0.11; P<.001). Subgroup analysis showed significant treatment effects of the single wide strip operation. Single-arm meta-analysis showed less annual axial elongation in children’s subgroups. These results were robust by sensitivity analysis. The incidence of some major complications in the operation group were significantly greater (5.8% vs 2.7% for myopic degeneration; 2.3% vs 1.6% for macular hemorrhage; 0.8% vs 0 for retinal detachment).

Authors note that posterior scleral reinforcement may be an effective surgery on controlling myopia progression by slowing both refraction and axial length change. However, frequent surgical complications should be considered. Further well-designed studies are needed to determine the long-term safety and efficacy.

Methodology: Inclusion criteria consisted of: 1) comparison study, including randomised clinical trials (RCT), cohorts, or non-RCT design studies; 2) the participants had myopia without retinoschisis, macular hole or retinal detachment; 3) studies that estimate the effect of PSR operation on controlling myopia progression; 4) the studies reported outcomes of spherical equivalent refraction (SER) or axial length (AXL). This meta-analysis was conducted in accordance with PRISMA guidelines. The search was performed on PubMed, Embase and Ovid, for studies published from the date of inception to 24 July 2019. We searched for the references of included studies. The search terms we used were in the supporting information, including myopia, scleral buckle, posterior sclera reinforce, scleroplasty, Snyder Thompson, and buckle reinforce. Both reviewers independently extracted data from the included articles for the author, publication year, study design, country, patient ages, sample size, intervention and control methods, follow-up duration, outcomes (change in SER and AXL) and corresponding 95% confidence interval (CI) and/or standard deviation (SD), and number of adverse effects. For postoperative complications analysis, studies with defined specific complication items were included. Studies in English were included. For the included studies, the methodological quality was appraised using the Newcastle-Ottawa Scale (NOS) for cohort studies. The Cochrane Risk of Bias tool was applied for RCTs. Disagreements over quality assessment were resolved by discussion or adjudicated by a third author (P.Y.L.). Statistical analyses for two-arm and single-arm meta-analyses were performed using Review Manager version 5.3 (Cochrane Collaboration) and Comprehesive Meta-Analysis Software version 3.0. In two-arm meta-analysis comparing PSR and control groups, for outcomes in all included studies, myopia progression and axial elongation, defined as change-from-baseline SER and AXL, the weighted mean difference (MD) between cases and controls, corresponding 95% CIs and standard errors were calculated and presented in forest plots. In single-arm meta-analysis, outcomes of the change-from-baseline SER and AXL were obtained from PSR groups, and the corresponding 95% CI were calculated. The effect size (ES) was calculated using the Hedges’ g to estimate the treatment effect for each outcome. Heterogeneity was assessed using I². We evaluated the pooled data for meta-analysis with a random-effects model. Statistical significance was set at a two-sided P<.05.

Applicability/external validity: The authors highlighted some limitations to be considered for external use of the findings: the number of studies included in this meta-analysis was limited. Some studies failed to report sufficient SD data for calculation, thus we imputed missing data by estimating the covariance (Cov) and correlation coefficient (r) reported by other studies in this meta-analysis. The ages and stages of children and corresponding different axial elongation rate may have important influences on the treatment effect. It was difficult to assess the complication rate.

Geographic focus: This review was conducted in high income countries – China and USA – with the majority of studies coming from China.

Summary of quality assessment:

Overall, there is medium confidence in the conclusions about the effects of this study. Authors did not conduct a thorough search of the literature to ensure that all relevant studies were identified and included in the review.