Corneal crosslinking (CXL) is still a novel procedure with different versions under investigation. In general, the procedure has two major types: epithelium-on and epithelium-off. But even within those categories schisms exist. Researchers from New Zealand recently published a study comparing the corneal densitometry changes after three styles of accelerated CXL: transepithelial pulsed (t-ACXL), epithelium-off continuous (c-ACXL) and epithelium-off pulsed (p-ACXL).

They found that c-ACXL induced more corneal haze than either p-ACXL or t-ACXL in the early postoperative period, but these differences resolved in approximately six months. For each procedure, the team reviewed 40 eyes. They evaluated the corneal tomography, densitometry and visual acuity of all 120 eyes preoperatively and at one, three, six, 12 and 24 months postoperatively.

The subjects’ total densitometry didn’t significantly change after t-ACXL and p-ACXL but did increase significantly after c-ACXL at one and three months, returning to baseline levels at the six-month visit, the investigators noted. These eyes remained stable for the remainder of the study follow-up. Within that same group, patients with steeper preoperative keratometry readings experienced a higher degree of CXL-induced corneal haze at one month. At one month, the mean change in densitometry of the t-ACXL group was significantly lower than the p-ACXL and c-ACXL groups. They reported no statistical difference in mean densitometry change between the three groups from six to 24 months.

Ziaei M, Gokul A, Vellara H, et al. Prospective two year study of changes in corneal density following transepithelial pulsed, epithelium-off continuous and epithelium-off pulsed, corneal crosslinking for keratoconus. Contact Lens & Anterior Eye. March 21, 2020. [Epub ahead of print].