Transepithelial Versus Epithelium-off Corneal Cross-Linking for the Treatment of Progressive Keratoconus: A Randomized Controlled Trial

Abstract

The recently published study by Soeters and associates 1 Soeters N. Wisse R.P. Godefrooij D.A. Imhof S.M. Tahzib N.G. Transepithelial versus epithelium-off corneal cross-linking for the treatment of progressive keratoconus: a randomized controlled trial. Am J Ophthalmol. 2015; 159: 821-828 Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar compared the clinical effects of transepithelial corneal cross-linking (CXL) with epithelium-off (epi-off) CXL in progressive keratoconus prospectively. This issue has recently been studied intensively by researchers, and this present study provides a valuable contribution to the literature that transepithelial CXL was not recommended because of continued keratoconus progression after 1 year. There are 2 topics involving the controversial aspects of transepithelial CXL treatment. One of them is the formulation of transepithelial riboflavin solutions. It was shown that the presence of dextran in transepithelial solution reduced the passage through the epithelium. 2 Wollensak G. Iomdina E. Biomechanical and histological changes after corneal crosslinking with and without epithelial debridement. J Cataract Refract Surg. 2009; 35: 540-546 Abstract Full Text Full Text PDF PubMed Scopus (228) Google Scholar However, Soeters and associates used Ricrolin TE, which consists of sodium EDTA 0.01%–TRIS 15% and dextran T500-riboflavin 0.1%. The second topic is the dosage of total ultraviolet-A (UVA) energy. It is well documented that corneal epithelium and Bowman layer decreases the passage of UVA and it was determined that the amount of blockage was approximately 20%–30%. 3 Podskochy A. Protective role of corneal epithelium against ultraviolet radiation damage. Acta Ophthalmol Scand. 2004; 82: 714-717 Crossref PubMed Scopus (84) Google Scholar So, the total dose of UVA energy should increase and a 7.2 J/cm2 dose is reasonable for transepithelial CXL. However, Soeters and associates used 5.4 J/cm2 total UVA energy. These 2 controversial topics may be associated with the failure of transepithelial CXL treatment in this present study. Additionally, the study entitled “Epithelial on or Epithelial off Corneal Collagen Cross-Linking: Bilateral Comparison Study” used dextran-free TE riboflavin solutions and 7.2 J/cm2 total UVA energy and showed that both techniques were able to stop progression at the end of 14.1 months (Yuksel E, et al. Epithelial on or epithelial off corneal collagen cross-linking: bilateral comparison study. 19th ESCRS Winter Meeting, Istanbul, Turkey; February 20–22, 2015.) Transepithelial Versus Epithelium-off Corneal Cross-linking for the Treatment of Progressive Keratoconus: A Randomized Controlled TrialAmerican Journal of OphthalmologyVol. 159Issue 5PreviewTo compare the clinical effects and safety of transepithelial corneal cross-linking (CXL) to epithelium-off (epi-off) CXL in progressive keratoconus. Full-Text PDF ReplyAmerican Journal of OphthalmologyVol. 160Issue 2PreviewWe would like to thank the authors for their comment on our recently published randomized transepithelial corneal cross-linking (CXL) study,1 and for their suggestions for failure of the transepithelial CXL technique. Full-Text PDF