Standard versus accelerated riboflavin-ultraviolet corneal collagen crosslinking: Resistance against enzymatic digestion.

PURPOSE: To examine the effect of standard and accelerated corneal collagen crosslinking (CXL) on corneal enzymatic resistance.

SETTING

School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom.

DESIGN

Experimental study.

METHODS

Sixty-six enucleated porcine eyes (with corneal epithelium removed) were assigned to 6 groups. Group 1 remained untreated, group 2 received dextran eyedrops, and groups 3 to 6 received riboflavin/dextran eyedrops. Group 4 had standard CXL (3 mW/cm(2) ultraviolet-A for 30 minutes), whereas groups 5 and 6 received accelerated CXL (9 mW/cm(2) for 10 minutes and 18 mW/cm(2) for 5 minutes, respectively). Trephined central 8.0 mm buttons from each cornea underwent pepsin digestion. Corneal diameter was measured daily, and the dry weight of 5 samples from each group was recorded after 12 days of digestion.

RESULTS

All CXL groups (4 to 6) took longer to digest and had a greater dry weight at 12 days (P < .0001) than the nonirradiated groups (1 to 3) (P < .0001). The time taken for complete digestion to occur did not differ between the standard and accelerated CXL groups, but the dry weights at 12 days showed significant differences between treatments: standard CXL 3 mW > accelerated CXL 9 mW > accelerated CXL 18 mW (P < .0001).

CONCLUSIONS

Standard and accelerated CXL both increased corneal enzymatic resistance; however, the amount of CXL might be less when accelerated CXL is used. The precise amount of CXL needed to prevent disease progression is not yet known.

FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.