Riboflavin dosing intervals do not impact CXL outcomes

This prospective, randomized trial compared the effectiveness of 2 riboflavin dosing intervals for corneal crosslinking (CXL).

Study design

The single-center study enrolled 510 patients with progressive keratoconus or ectasia after refractive surgery. Each patient underwent standard epithelial-off CXL in 1 eye, with either 2-minute (n=257) or 5-minute (n=253) riboflavin dosing intervals.

In some cases, fellow eyes (n=207) were also treated with 5-minute dosing intervals, and considered in the safety analysis.

Outcomes

Six months after treatment, both groups had equivalent improvements in maximum keratometry, CDVA and UDVA. Of the 635 study and fellow eyes, 134 (21%) gained and 32 (5%) lost 2 or more lines of CDVA.

Complications were uncommon and included sterile infiltrates (n=3), delayed epithelial healing with dendrites (n=1) and recurrent epithelial defects (n=3). Three eyes required re-treatment.

Limitations

The chief limitation of this study was its short follow-up of 6 months.

Clinical significance

There was no difference in safety or outcomes between 2-minute and 5-minute riboflavin dosing intervals during standard CXL.

This finding was contrary to the study authors' hypothesis that increased frequency of dosing of isotonic riboflavin solution might result in decreased absorption of incident ultraviolet A light (due to the solution's viscous nature), which might have affected outcomes or safety.