Comparison of Epithelium-Off Versus Transepithelial Corneal Collagen Cross-Linking for Keratoconus: A Systematic Review and Meta-Analysis

source extracted confidence: high 2026-04-09
#collagen #cornea #corneal-pachymetry #corneal-topography #cross-linking-reagents

Comparison of Epithelium-Off Versus Transepithelial Corneal Collagen Cross-Linking for Keratoconus: A Systematic Review and Meta-Analysis

Wen et al., 2018 | Cornea | Meta Analysis

Citation

Wen Daizong, Song Benhao, ... Huang Jinhai. Comparison of Epithelium-Off Versus Transepithelial Corneal Collagen Cross-Linking for Keratoconus: A Systematic Review and Meta-Analysis. Cornea. 2018-Aug;37(8):1018-1024. doi:10.1097/ICO.0000000000001632

Abstract

PURPOSE: To systematically compare standard epithelium-off corneal collagen cross-linking (SCXL) and transepithelial corneal collagen cross-linking (TECXL) for treating keratoconus. METHODS: PubMed, EMBASE, the Cochrane Library, the US trial registry (ClinicalTrials.gov), VIP Database, Wanfang Databse, and China National Knowledge Infrastructure searches up to February 2017 were conducted. Primary outcomes were changes at 1 year in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes at 1 year in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness, endothelial cell density, and the occurrence of adverse events. RESULTS: Eight studies with a total of 455 eyes were included. For primary outcomes, SCXL showed a greater reduction in mean K [standardized mean difference (SMD) 0.28; 95% confidence interval (CI), 0.03-0.53; P = 0.03] compared with TECXL. Subgroup analysis indicated that SCXL had a comparable effect on reducing mean K with TECXL protocols using chemical enhancers (SMD 0.05; 95% CI, -0.36 to 0.45; P = 0.82) but a greater reduction in mean K compared with TECXL with current iontophoretic protocols (SMD 0.43; 95% CI, 0.10-0.75; P = 0.01). For the other outcomes, there were no statistically significant differences. CONCLUSIONS: With the exception of less reduction in mean K with current iontophoretic protocols, analysis of the limited number of comparative studies available seems to demonstrate that SCXL and TECXL have a comparable effect on visual, refractive, pachymetric, and endothelial parameters at 1 year after surgery. Further follow-up is required to determine whether these techniques are comparable in the long-term.

Key Findings

Eight studies with a total of 455 eyes were included. For primary outcomes, SCXL showed a greater reduction in mean K [standardized mean difference (SMD) 0.28; 95% confidence interval (CI), 0.03-0.53; P = 0.03] compared with TECXL. Subgroup analysis indicated that SCXL had a comparable effect on reducing mean K with TECXL protocols using chemical enhancers (SMD 0.05; 95% CI, -0.36 to 0.45; P = 0.82) but a greater reduction in mean K compared with TECXL with current iontophoretic protocols (SMD 0

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Collagen
  • Cornea
  • Corneal Pachymetry
  • Corneal Topography
  • Cross-Linking Reagents
  • Drug Administration Routes
  • Epithelium, Corneal
  • Humans
  • Keratoconus
  • Photochemotherapy
  • Photosensitizing Agents
  • Riboflavin
  • Ultraviolet Rays

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Systematic Review
  • Vertical: collagen

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09