Keratoconus (KC) patients who undergo transepithelial, or “epi-on,” corneal collagen crosslinking (CXL) may have haze issues in the months following treatment, but this should resolve within a year of the procedure, a study in Cornea reports.

The researchers found that after epi-on CXL, corneal haze increased slightly at one month, plateaued between months one and three and returned to baseline between three and 12 months.

“Transepithelial corneal crosslinking appears to be effective in decreasing maximum K and uncorrected vision in KC, but perhaps less robust than standard CXL,” researcher Peter S. Hersh, MD, says. “Corneal haze associated with the CXL is substantially less using the transepithelial technique. How this relates to procedure efficacy remains unclear.”

Dr. Hersh and his team enrolled 59 eyes of 43 keratoconus patients who underwent epi-on CXL and then were randomized into two groups. Group one received intraoperative riboflavin 0.1% every minute and group two received riboflavin 0.1% every two minutes during ultraviolet exposure. Scheimpflug densitometry was measured preoperatively and at one, three, six and 12 months. The researchers also correlated densitometry measurements with visual acuity, pachymetry and topography results.

Baseline pre-op corneal densitometry was 20.45±2.79, which increased at one month (22.58±3.79). However, no significant change was observed between months one and three (22.64±3.83), and a significant improvement was noted between months three and 12 (21.59±3.39 and 20.80±3.27, respectively).

No difference was found between preoperative densitometry measurements and those taken at one year. Additionally, there was no marked difference between the one-minute and two-minute subgroups.

The study also found that corneal densitometry readings at three months and one year didn’t appear to correlate with uncorrected distance visual acuity, corrected distance visual acuity, or maximum keratometry one year after CXL.

J Lai M, Greenstein SA, Gelles JD, Hersh PS. Corneal haze after transepithelial collagen cross-linking for keratoconus: a Scheimpflug densitometry analysis. Cornea. April 8, 2020. [Epub ahead of print].