Patients With Keratoconus Benefit From Off-Label Procedure

An Expert Interview With Leejee H. Suh, MD

Troy Brown

February 07, 2012

February 7, 2012 (Miami, Florida) — Corneal crosslinking is a procedure that is being used in other countries but has not yet been approved by the US Food and Drug Administration (FDA) in the United States.

Leejee H. Suh, MD, assistant professor of clinical ophthalmology at the University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, in Miami, Florida, discussed current treatments for keratoconus, including corneal crosslinking, at the Bascom Palmer Eye Institute 50th Anniversary Scientific Meeting in Miami with Medscape Medical News.

Medscape: What is corneal crosslinking and how does it work?

Dr. Suh: Corneal collagen crosslinking has been practiced a lot in Europe and other countries, but it's not FDA-approved in America. It's a combination of a vitamin called riboflavin and UVA light at a very low dose, which is not harmful to the patient or to the other parts of the eye. That combination crosslinks and hardens the cornea. That actually happens with age, but it's used a lot in keratoconus corneas because they're more malleable, they protrude, and they bend, so if you crosslink these corneas early on, it may prevent progression. The focus is on finding patients with early-stage disease and offering them crosslinking to prevent further progression. The model is kind of like glaucoma detection — you prevent further vision loss by identifying patients early and treating them.

Medscape: How is keratoconus diagnosed?

Dr. Suh: It can actually present very early; I've seen patients as young as 11 years of age. They basically present with a change in prescription every few months. We find a lot of the patients when they go for a laser vision correction evaluation. A way to detect it in an earlier subtle manner is to take a picture, a corneal map called topography, that often will show subtle signs. That's how we're identifying a lot of the earlier patients.

Medscape: What steps are being taken in the United States to get this procedure approved by the FDA?

Dr. Suh: There are 2 companies, Avedro and Topcon, that are running trials. Bascom Palmer is working with Avedro to provide the trial at Bascom Palmer, in the hopes of getting enough data that it will ultimately get FDA approval. There are private practitioners performing the procedure using a commercially purchased UVA light source and riboflavin sources; they're performing the procedure on an off-label basis, with the understanding that it's not FDA-approved.

The reason a lot of practitioners are already performing the procedure is that the data are very convincing outside of the United States. Technology may be more advanced outside of the United States, and it takes a while to get FDA approval here.

Medscape: What is transepithelial crosslinking?

Dr. Suh: In the original protocol, in order to get the riboflavin to penetrate the cornea, the epithelium — the outermost layer of the cornea — is removed. But when you do that, it can cause pain for the patient. Also, if patients are not given antibiotic coverage, they can develop infections. To reduce postoperative pain and reduce the risk of infection, there are certain procedures that can loosen the epithelium to allow riboflavin to penetrate through an intact epithelium. That's another method that a lot of groups are looking at, because it allows for penetration of riboflavin and allows for better comfort for the patient. The data are convincing that it's possibly as effective as the epithelium-removal protocol, but that has yet to be determined.

Medscape: Will corneal crosslinking eliminate the need for corneal transplants for keratoconus?

Dr. Suh: That's the ultimate goal. I think if we can find our patients earlier on and we can crosslink them, we can slow down or stop progression, but we still need more prospective studies. We need longer studies to know how long the effect lasts.... The research of the original group that performed crosslinking in Germany has been out for 10 years and it looks convincing. The data overall are convincing enough for physicians to perform the procedure without FDA approval; that's what's going on in the United States right now. It would definitely reduce the need for keratoconus patients to require surgery.

Medscape: What are the risks associated with corneal crosslinking?

Dr. Suh: There have been cases of infection that developed after corneal crosslinking, and sometimes you can get scar tissue formation. It doesn't work for everybody. Those are low risks, but they're possible.

Medscape: How do patients tolerate the procedure?

For contact-lens wearers, when you have the procedure, you can't wear your contact lenses until the site has healed. There's a little bit of downtime, but for the most part, the eyes heal well even if you remove the epithelium. The key thing for patients to know is that this is not to heal your vision. This is not like laser surgery, like LASIK, to improve your uncorrected visual acuity.

The data have shown that it probably halts progression, but it doesn't significantly improve vision. For some patients, it does a little bit, but the goal is not to improve vision; it is to prevent further progression.

Medscape: What unanswered questions do you have about keratoconus?

Dr. Suh: We still don't know what causes keratoconus. We don't know why patients develop keratoconus. There are some genetics associated with this, but it's not clear. We know that eye rubbing is associated with progression, but we really don't know why. The need for research to determine why this is happening is very important. I think combining the treatments that are out there is another important area of research.

Dr. Suh has disclosed no relevant financial relationships.

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