Corneal collagen cross-linking improves long-term VA in treating keratoconus, ectasia

J Cataract Refract Surg. 2011;37(1):149-160.

Issue: February 10, 2011

Corneal collagen cross-linking markedly improved visual acuity in patients with keratoconus or corneal ectasia, a study found.

"Corneal collagen cross-linking is a promising new treatment for keratoconus and corneal ectasia," the study authors said. "Cross-linking is thought to biomechanically strengthen the corneal stroma and, consequently, slow the progression of keratoconus and ectasia. In many cases, moreover, [corneal collagen cross-linking] improves the patient's visual, refractive, and topographic outcomes with few reported complications."

The prospective, randomized clinical trial included 71 eyes of 58 patients who underwent standard corneal collagen cross-linking with ultraviolet and riboflavin 0.1%; 49 eyes had keratoconus and 22 eyes had post-LASIK corneal ectasia. A control group of 41 eyes underwent sham treatment with riboflavin 0.1% alone. A fellow-eye control group comprised 30 fellow eyes of patients who did not undergo bilateral cross-linking.

Patients were followed for up to 12 months postoperatively.

Results showed no significant differences between the treatment group and sham control group in changes from baseline to 3-month uncorrected distance visual acuity, corrected distance visual acuity, maximum keratometry value and average keratometry value.

At 1 year, the treatment group had statistically significantly better outcomes in all measures than the fellow-eye control group.

Uncorrected distance visual acuity and corrected distance visual acuity improved significantly from baseline to 12 months (P = .04 and P < .001, respectively). The keratoconus and ectasia subgroups had significant improvement in corrected distance visual acuity (P < .001 and P = .02).

Topographic measurements improved more in keratoconus patients than in those with ectasia.

This is one of the very few independent prospective randomized controlled clinical trials that have been published on collagen cross-linking. This topic has taken relevance in podium presentations worldwide, and has also been addressed in some scientific papers in the peer review literature. However, few articles deal with really scientific randomized controlled clinical trials. The authors confirm previous opinions about collagen cross-linking. It is clear that this technique offers an advantage in the treatment of keratoconus or corneal ectasia, which is manifest with time. The authors rightly describe the normal evolution of the collagen cross-linking patient, with worsening of the visual condition at the beginning and late improvement after 3 months, with a progressive positive evolution that may last even 1 year postoperatively. The authors also confirm the unpredictability of the outcomes and provide an important insight into what is to be expected from the actual way in which collagen cross-linking is performed nowadays. The surgeons using collagen cross-linking for their keratoconus patients should be aware that any refractive action to be decided on these patients should be taken even after 1 year following collagen cross-linking. This not only affects corneal excimer laser procedures but also intraocular phakic lenses or other intraocular procedures such as cataract. Predictability based on corneal variability is indeed affected. These authors also make an important contribution highlighting the variability of the outcome, an important question about issues such as topographic guided excimer laser procedures associated to or following collagen cross-linking. With this basic variability of the outcome, very little should be expected from the topographic guidance that can be obtained preoperatively as there is no relation between the postoperative outcomes with the preop. The authors have to be congratulated for this important input into the knowledge of collagen cross-linking from this independent well-performed study.

– Jorge L. Alió, MD, PhD
OSN Europe Edition Board Member
Disclosure: No products or companies are mentioned that would require financial disclosure.