Corneal Collagen Crosslinking
Keratoconus is a non-inflammatory deformation of the cornea associated with thinning and biochemical weakening. Corneal ectasia is a similar disease which results in deformation of the cornea after refractive surgery such as LASIK or PRK. The incidence of keratoconus is about one in every 2000 cases and hundreds of cases of corneal ectasia were reported in the medical literature.
In keratoconus, the corneal surface bulges forward into a cone like shape. This results in irregular astigmatism, progressive near-sightedness, and scarring of the central cornea. To see clearly, patients often require rigid gas permeable contact lenses. However in more advanced cases, contact lens fitting may not be possible. Keratoconus tends to progress between the ages of 20-50, after which it tends to stabilize.
Keratoconus is the second most frequent indication for corneal transplantation. Full thickness corneal transplantation is needed in 10-20% of cases. Treatments for keratoconus and corneal ectasia include intrastromal corneal ring implants, conductive keratoplasty, and corneal collagen crosslinking. In the past, crosslinking was only available to patients in Europe and Canada, forcing American patients to travel abroad or participate in clinical trials in the United States to be treated. Corneal collagen crosslinking was finally approved by the FDA in the United States earlier this year for treatment of progressive keratoconus and corneal ectasia after refractive surgery.
The treatment begins by removal of the corneal epithelium, which is the outermost layer of the cornea. Riboflavin, which is vitamin B2, is applied to the corneal surface, followed by UV light. The combination of riboflavin and UV light results in formation of reactive oxygen species, which in turn create additional covalent bonds between corneal collagen molecules. Additional bonds result in biomechanical stiffening of the cornea. Crosslinking decreases keratoconus progression, decreases the steepness of the cone, and improves uncorrected and best corrected visual acuity in some cases. Crosslinking can also delay or prevent corneal transplantation. If you would like to learn more about these new technologies, please call (800) 708-8800 to schedule a consult.