FDA trial data positive for corneal collagen crosslinking

San Francisco-An interim analysis of data from an ongoing U.S. clinical trial shows corneal collagen crosslinking using riboflavin and ultraviolet A (UVA) light has promising efficacy and safety for the treatment of progressive keratoconus and postLASIK ectasia, said R. Doyle Stulting, MD, PhD, professor of ophthalmology, Emory University, Atlanta.

"By inducing covalent bonds between collagen molecules, corneal collagen crosslinking appears to halt the progression of these ectatic corneal diseases, decrease corneal curvature and thickness, and increase corneal rigidity," Dr. Stulting said. "As a pleasant but unexpected surprise, we also are seeing that the effect on corneal curvature appears to increase between 3 and 6 months, and data from international studies having follow-up to 5 years suggest it may last indefinitely. Now, we look forward to the final study results that [it is hoped] will lead to FDA approval of this treatment in the United States."

The U.S. clinical trial has a block-randomized design in which one eligible eye of enrolled patients is assigned to undergo riboflavin/UVA crosslinking or sham treatment. Control eyes and untreated fellow eyes can receive the crosslinking treatment at 3 months. Follow-up is planned to 1 year.

The main outcome measures include change in keratometry and best spectacle-corrected visual acuity. So far, 457 eyes have been treated with riboflavin/UVA collagen crosslinking, he said. Whether eyes are divided into subgroups based on diagnosis or pooled, the data show corneal curvature (Kmax and average central K) increases at 1 month after the active procedure but decreases at 3 months and is reduced further at 6 months.

In contrast, corneal curvature continues to increase in control eyes over time, Dr. Stulting said.

Only a few complications have been recorded. These include four infiltrates (0.8%), four cases of delayed re-epithelialization, and one case of uveitis, which was deemed by the investigator to be of uncertain relationship to the treatment.