Transepithelial cross-linking may be less efficient in treating progressive keratoconus

Issue: September 25, 2012

Transepithelial collagen cross-linking stabilized progressive keratoconus less effectively than standard cross-linking, a study found.

Perspective from George O. Waring IV, MD

The prospective cohort study included 53 eyes of 38 patients with progressive keratoconus; mean patient age was 24.02 years.

Corrected distance visual acuity, manifest sphere, cylinder, keratometric values and simulated keratometry measurements were evaluated at baseline, at 1, 3 and 6 months after treatment, and at subsequent 6-month intervals.

Placido disk topography and Scheimpflug tomography were used to assess keratometry values and corneal pachymetry.

Proparacaine 0.5% preserved with benzalkonium chloride 0.005% was instilled before riboflavin and ultraviolet-A light were applied.

Study results showed that maximum keratometry, simulated keratometry and refractive power remained stable 18 months after treatment. Only corrected distance visual acuity improved significantly at 6 and 12 months.

The inferior-superior value increased significantly at all follow-up points. Scheimpflug imaging showed a significant increase in maximum keratometry value and an appreciable decrease in pachymetry at the thinnest point of the cornea at all time points.

“The different result regarding the change in maximum [keratometry] values between Placido-based topography and elevation-based topography in our study is an unexpected finding,” the authors said.

No cases of corneal haze or other complications were reported.

Perspective

George O. Waring IV, MD

This study evaluating transepithelial collagen cross-linking for the treatment of keratoconus is an important and needed contribution to the literature. Although not a comparative trial, it helps characterize the potential benefits and more importantly, limitations of transepithelial riboflavin delivery with benzalkonium chloride (0.005%). Given these results showing progression of keratoconus with the studied transepithelial technique, we are likely to observe two things: improvements in transepithelial delivery methods and patient selection decision criteria for the standard epi-off technique and transepithelial delivery of riboflavin for collagen cross-linking.

George O. Waring IV, MD

Director of Refractive Surgery, Assistant Professor of Ophthalmology; Storm Eye Institute, Medical University of South Carolina; Medical Director, Magill Vision Center, Charleston, S.C.

Disclosures: Waring is chairman of the scientific advisory board and a consultant to Topcon collagen cross-linking technologies.

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Source:

J Cataract Refract Surg. 2012;38(6):1000-1005.