Corneal collagen crosslinking indications expanding

New York-Indications for riboflavin ultraviolet crosslinking have been expanding. As such, the technology may be useful for more than just treating keratoconus-by filling a gap in which other surface therapies sometimes cannot be effective.

The indications include stabilizing ectatic corneas, followed by excimer laser ablation or other procedures to improve vision; pre-treating eyes at risk for ectasia to increase the number of candidates for refractive corneal surgery, antimicrobial treatment, stabilizing eyes that have undergone radial keratotomy, treating sterile corneal ulceration, and treating corneal edema.

Eric D. Donnenfeld, MD, in discussing new applications, noted that ultraviolet A has a long history of use for sterilizing drinking water and use with riboflavin to sterilize blood products. Dr. Donnenfeld is a founding partner of Ophthalmic Consultants of Long Island and Connecticut; clinical professor ophthalmology, New York University Medical Center, New York; and a trustee of Dartmouth Medical School.

In addition, melting in corneal ulcers can be halted with crosslinking (2.5 mW/cm²/30 minutes). The crosslinked corneas have increased resistance to enzymatic degradation and melting. Crosslinking may stabilize proteolysis by making collagen less prone to melt by infectious processes and sterilize the infection, he noted.

Possible treatment-related concerns are apoptosis of keratocytes, potential toxicity of the endothelium, limbal cells, and/or goblet cells.

PRK patients may also benefit from UVA crosslinking. Significant improvements in visual acuity have occurred when the technology was combined with topographic PRK after development of post-LASIK ectasia and keratoconus. There is a potential use for UV crosslinking in high-risk PRK (i.e., those with form fruste keratoconus, thin corneas, high myopia, and young patients).

Concerns include the addition of a refractive variable to the procedure due to corneal flattening associated with riboflavin UV crosslinking, Dr. Donnenfeld said.

In addition, patients who have undergone radial keratotomy, have bullous keratopathy, and those with stromal ring implants may benefit from the technology, he noted. In bullous keratopathy, for example, crosslinking improves corneal transparency, corneal thickness, and ocular pain 1 month after treatment, but there is no long-lasting effect in decreasing pain and maintaining corneal transparency in these patients.

This article was adapted from Dr. Donnenfeld’s presentation at the annual meeting of the American Society of Cataract and Refractive Surgery.

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