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Updated: Nov 11, 2025
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Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis
Published on: November 12, 2015
20.1K
Transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus
Sueko M Ng1, Mark Ren2, Kristina B Lindsley3
1Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, CO, USA.
The Cochrane Database of Systematic Reviews
|March 25, 2021
Summary
Transepithelial corneal collagen crosslinking (CXL) shows similar effectiveness to standard epithelium-off CXL for progressive keratoconus. Further research is needed to determine long-term benefits and optimal treatment protocols.
Area of Science:
- Ophthalmology
- Corneal Science
- Vision Research
Background:
- Keratoconus, a common corneal dystrophy, causes vision loss due to corneal thinning and scarring.
- Corneal collagen crosslinking (CXL) is the only treatment to slow keratoconus progression.
- Transepithelial CXL (teCXL) is an alternative to standard epithelium-off CXL, potentially offering faster healing and less discomfort.
Purpose of the Study:
- To compare the short- and long-term effectiveness and safety of transepithelial CXL versus epithelium-off CXL for progressive keratoconus.
Main Methods:
- Systematic review and meta-analysis of randomized controlled trials (RCTs).
- Searched multiple databases (CENTRAL, MEDLINE, Embase, PubMed, LILACS, ClinicalTrials.gov, ICTRP) up to January 2020.
- Included 13 RCTs with 723 eyes comparing teCXL with epithelium-off CXL in progressive keratoconus patients.
Main Results:
- No significant difference in maximum keratometry (Kmax) between teCXL and epithelium-off CXL at 12 months or later (very low certainty evidence).
- Evidence is uncertain regarding the effect on keratoconus stabilization and visual acuity outcomes.
- Epithelium-off CXL showed a slight increase in corneal haze/scarring compared to teCXL (moderate certainty evidence).
Conclusions:
- Due to imprecision and reporting inconsistencies, it remains unknown if teCXL offers an advantage over epithelium-off CXL for keratoconus progression or visual outcomes.
- Future trials should prioritize arrest of keratoconus progression as the primary outcome and standardize assessment methods.
- Longer follow-up periods and standardized care protocols are needed to reliably compare CXL methods.
