What is the mechanism of corneal collagen cross-linking in equine ulcers?

• A. Riboflavin applied topically then targeted UV light to induce collagen cross-links
• B. Antibiotics plus steroids to reduce inflammation
• C. Salt solution application to strengthen the cornea
• D. Laser ablation to remove damaged tissue

Answer: (A)

Corneal collagen cross-linking strengthens the cornea by a light-activated chemical process. Topically apply riboflavin (vitamin B2) to the cornea to saturate the stroma, then expose the area to ultraviolet-A light. This combination activates riboflavin to produce reactive species that create new covalent bonds between collagen fibers and the surrounding matrix, increasing the cornea’s biomechanical stiffness. In equine ulcers, this added rigidity helps resist further melting and tearing, reducing the risk of perforation and slowing enzymatic degradation of the corneal stroma.

The other approaches don’t achieve this structural reinforcement: antibiotics and steroids address infection or inflammation but don’t cross-link collagen; a salt solution lacks a mechanism to strengthen the tissue; laser ablation removes tissue rather than improving the cornea’s structural integrity.