Keratoconus management greatly improved, but questions remain

Joseph Colin

For many years, the only possible options for keratoconus patients were spectacles in mild cases, contact lenses as soon as the vision was unsatisfactory with glasses, and penetrating keratoplasty for contact lens-intolerant patients or those with low vision despite contact lens tolerance.

Recently, new treatment options have dramatically changed the management of patients with corneal ectasia. CXL was discussed in detail by experts at the Eurokeratoconus Congress held in Bordeaux, France, in September 2011.

Implantation of intracorneal rings has allowed patients with contact lens intolerance to improve their vision by reshaping the cornea, which in many cases prevents the need for a corneal graft.

Penetrating keratoplasty has been replaced in most cases by deep anterior lamellar keratoplasty, preserving the healthy endothelial cells of the patient.

A major advance has been the development of corneal cross-linking (CXL), a technology that is able, at least with current follow-up, to inhibit the progression of keratoconus in almost 95% of cases and improve vision by corneal flattening.

The standard CXL procedure includes a central de-epithelialization of the cornea, a 30-minute soaking of the stroma with riboflavin drops and a 30-minute 3 mW UVA irradiation to obtain the stromal cross-linking. The possibility of performing corneal CXL without removal of the epithelium has been a hot topic of discussion lately. After initial skepticism, it seems that most of the keratoconus specialists today are moving toward this therapeutic modality.

The advantages of epi-on CXL are obvious because of the absence of post-treatment pain, which is much appreciated by patients, especially children, and a decreased risk of complications, including epithelial healing issues, infectious keratitis and corneal scar formation.

Major approaches

Two major approaches to CXL are currently used. One approach involves making the epithelium permeable by using different physical or chemical agents to open the tight junctions of the epithelium. A wide variety of compounds and combinations of compounds are being tried, and it is not yet clear which works best.

The second approach involves changing the pharmacologic properties of riboflavin to allow the penetration of the active drug through the epithelium or using a specific strategy such as iontophoresis.

There is a need for follow-up with additional future research.

Some preliminary studies have shown that epi-on CXL can halt the progression of keratoconus compared with fellow eyes with no treatment. The main question that has to be answered concerns the comparative efficacy of epi-on techniques and standard epi-off procedures. Confocal microscopy analysis has demonstrated that CXL is much more superficial when using the epi-on technique. If prospective studies can achieve results that are just as good as the original protocol epi-off CXL, it will obviously be our first choice for progressive keratoconus treatment.

Another new approach for CXL is the possibility of using a shorter treatment time with higher energy, such as 10 minutes, 10 mW, or 3 minutes, 30 mW. The efficacy and safety of this new regimen will have to be compared with standard CXL.

It seems logical to treat children with progressive astigmatism with CXL as soon as keratoconus is diagnosed to stop the disease before it advances to a severe grade, when it is much more difficult to manage.

And why not have the dream of suppressing clinical keratoconus with an early CXL treatment as soon as the ectasia occurs?

Unanswered questions

Unanswered questions remain.

How many years will CXL be efficient in keratoconus-treated patients? Which is the best treatment, epi-on or epi-off? Is fast, high-energy CXL as efficient as longer, low-energy CXL?

Is CXL combined with LASIK or PRK effective and safe in patients with suspect corneas? Is CXL indicated for progressive keratoconus only or for all keratoconus? Will CXL be reimbursed by insurance?

Finally, which is the best sequence for combining CXL and intracorneal rings?

• Joseph Colin, MD, can be reached at Hôpital Pellegrin, Place Amélie Raba-Lèon, 33076 Bordeaux, France; +33-5-56795608; fax: +33-5-56795909; email: joseph.colin@chu-bordeaux.fr.
• Disclosure: Dr. Colin is a consultant for Addition Technology.