Transepithelial Corneal Collagen Cross-Linking in Keratoconus

Abstract

A limited but favorable effect of transepithelial CXL was noted on keratoconic eyes, without complications. The effect appears to be less pronounced than described in the literature after CXL with de-epithelialization.

New clinical pathways for keratoconus

“…32 Two prospective, paired-eye studies in humans have documented small, but significant improvements in CDVA over fellow untreated eyes at 12 and 18 months, respectively, with a trend towards deterioration in topographic and acuity measures in non-treated control eyes. 33,34 Improvements in corneal curvature (B2D mean reduction in Kmax) were similar to those seen after epithelium-off CXL. Statistically significant improvements in CDVA were also observed in an uncontrolled prospective study, 35 though the authors recorded conflicting keratometric results depending on the imaging device used (progression by Scheimpflug, no change by Placido disc).…”

“…[37][38][39] These risk factors for disease progression are often present at presentation, and may be compounded if further disease progression is allowed to occur. Based on this, the proven efficacy of CXL, 14,18,19,21,22 the higher risk of CXL-related visual loss aged 435 years, 22 and the relative safety of transepithelial treatment, 33,34 we believe that there is a rational argument for transepithelial CXL at presentation for patients r35 years of age with keratometric stage II disease (Figures 2 and 3). 9 For patients over 35 years without other risk factors, the risk of progression is lower (and CXL-related complications higher), so no intervention is required at presentation.…”

Effect of corneal epithelium on ultraviolet-A and riboflavin absorption

“…Moreover, the epithelium may block UV rays (27)(28)(29) . Despite this recommendation, some ophthalmologists have adopted the "epi-on" technique, with intact epithelium (13,14) . This technique, also called transepithelial CXL, attempts to minimize possible complications due to epithelial debridement such as corneal ulcer, infections, haze as well as photophobia, prolonged recovery time and pain.…”

“…In a clinical study, Leccisotti et al (14) found a limited but favorable effect of transepithelial CXL in keratoconus eyes. They reported that this effect appeared to be less pronounced than described in the literature after CXL with de-epithelialization.…”

“…However, removal of the epithelium can increase the risks of corneal infections, ulcers, haze, scarring and infiltrates, beyond longer recovery time, discomfort and postoperative pain experienced by patients (9)(10)(11)(12) . Recently, slight modifications of this technique were proposed to overcome the potential disadvantages of epithelium removal: one approach advocates the use of multiple applications of topical anesthetic eye drops to loosen the tight junctions of the corneal epithelial cells, thus facilitating riboflavin penetration through an intact epithelium (13,14) . Others per-form a grid-like pattern de-epithelialization instead of complete epithelial removal, attempting to hasten postoperative healing (15) .…”