Collagen crosslinking (CXL) appears to reduce corneal thickness in patients with bullous keratopathy (BK), at least in the initial four weeks after surgery, researchers from Hong Kong suggest. However, their study also found patients who underwent CXL had no greater improvements in pain, corneal clarity or vision compared with the control group, and the short-term benefits of the procedure were unlikely to outweigh its potential risk of recurrent epithelial defect.

The study enrolled 42 patients with BK, of which 26 were randomized to receive CXL, and 16 were placed in the placebo group that received the same riboflavin solution, but underwent a sham debridement and UV light treatment. The patients were assessed at baseline and up to 12 months after treatment.

The central corneal thickness in the CXL group was reduced by 37.6μm and 63.8μm at two and four weeks, respectively, which was significantly higher than the control group. However, there was no statistical difference in central corneal thickness reduction between the two groups at 12 weeks and during later follow-ups. While the CXL group reported lower pain scores throughout the one-year follow-up, the same was true of the control group, suggesting a placebo effect, the researchers note.

Of note: CXL was associated with more recurrent epithelial defect (12%), and two of the three subjects with epithelial defect required amniotic membrane transplant.

“Considering its side effects of recurrent epithelial defect, which might require further treatment, including amniotic membrane transplant, CXL might not be warranted as a treatment alternative in patients with BK,” the researchers wrote in their paper.

Choy BNK, Ng ALK, Zhu MM, et al. Randomized control trial on the effectiveness of collagen cross-linking on bullous keratopathy. Cornea. July 1, 2020. [Epub ahead of print].