Dataset Information

Corneal collagen cross-linking epithelium-on vs. epithelium-off: a systematic review and meta-analysis.

ABSTRACT:

Background

The purpose of the study was to determine the advantages and disadvantages of epi-on corneal cross-linking (CXL) techniques compared with standard epi-off CXL.

Methods

We searched MEDLINE and EMBASE for randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) and we evaluated the selected papers according to the Cochrane risk of bias tool. We considered, as primary outcomes, average Kmax flattening, changes in uncorrected and corrected distance visual acuity (UDVA and CDVA); as secondary outcomes, we considered changes in pachymetry values and endothelial cell density (ECD). We also investigated adverse events related to the treatments and treatment failure. Meta-analysis was conducted with a fixed or random-effects model using weighted mean difference (MD) with 95% confidence interval (CI) as the effect size.

Results

A total of 15 studies were included and among these 15 trials, 9 were RCTs and 6 were NRSIs, but only 4 studies showed no high risk of bias and were included in this meta-analysis. Our analysis revealed significant postoperative differences in CDVA (MD = 0.07; 95% CI 0.04 to 0.10; P < 0.001), and no significative differences in UDVA, Kmax, central corneal thickness (CCT) and ECD (P > 0.05). Epi-on CXL protocol was found to be significantly less prompt to have risks of delay in epithelial healing (P = 0.035) and persistent stromal haze (P = 0.026).

Conclusion

Epi-on CXL is as effective as epi-off CXL. Except for a higher significant improvement in CDVA with current epi-on protocols, our meta-analysis demonstrates that epi-on and epi-off CXL have comparable effects on visual, topographic, pachymetric, and endothelial parameters. Epi-on CXL has clinical advantages in terms of comfort and avoidance of complications as it reduces the risk of developing delay in epithelial healing and persistent stromal haze.

SUBMITTER: D'Oria F

PROVIDER: S-EPMC8465763 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionCorneal ectasias are progressive, degenerative ocular diseases defined by abnormal structural changes in the cornea, leading to distortion of vision and substantial reduction in quality of life. Corneal collagen cross-linking (CXL) increases the biomechanical rigidity of the cornea and has been shown to halt ectatic processes. The established CXL protocol requires removal of the corneal epithelium. However, some surgeons have proposed transepithelial approaches to enhance patient recovery and minimise adverse events. Whether novel transepithelial approaches are as effective in arresting ectasia as the established epithelium-off protocol remains unclear. This study will systematically review the evidence on transepithelial CXL approaches and compare it to the epithelium-off protocol.Methods and analysisWe will include randomised controlled trials (RCTs) comparing transepithelial and epithelium-off CXL for any corneal ectasia. We will search 16 electronic databases including MEDLINE and Embase, as well as the grey literature. Two reviewers will independently screen search results to identify eligible studies, complete data abstraction and conduct quality assessment. We will assess the quality of individual RCTs using the Cochrane risk of bias assessment tool. Our primary outcome will be the change in maximal keratometry at 12 months after treatment, and we will examine 11 additional outcomes. We will summarise our analyses by measures of association (relative risk or odds ratio) and corresponding 95% confidence intervals (CIs) for dichotomous outcomes and weighted mean differences with 95% CIs for continuous outcomes. Prespecified subgroup analyses will be conducted to explore heterogeneity. The overall quality of evidence will be rated using the Grading of Recommendations Assessment, Development and Evaluation approach.Ethics and disseminationEthics approval is not required for this systematic review as it draws from previously published data. Results of the study will be submitted to a peer-reviewed journal for publication and discussed at conferences and seminars.Prospero registration numberCRD42018102069.