What is Corneal Collagen Crosslinking?
Corneal Collagen Cross-Linking
Corneal collagen crosslinking is a photo-chemical procedure to make your cornea stiffer by bonding the collagen fibers with riboflavin and ultraviolet light, suggested by Switzerland professor Theo Seiler, MD.
Cross-linkage theory of aging
Tissues in the body especially collagen develop cross-links at the cellular level as the tissue ages, this cross-linkages cause the tissue to become less elastic and interfere with normal function 1
Basically with corneal collagen cross-linking you are making your cornea older.
The stability of a keratoconus cornea may be increased by photo-oxidative collagen crosslinking with riboflavin and ultraviolet light.
This is supposed to stop the progression of the keratoconus by improving its resistance to proteolytic enzyme damage.
The procedure is performed as an outpatient treatment.
Riboflavin is vitamin B2, is non-toxic, widely available and safe in 400mg daily doses, it has the function of absorbing ultraviolet radiation and producing reactive oxygen species.
Epi-off crosslinking
The epi-off (FDA approved) procedure is after topical anesthesia to remove the epithelium of the cornea, around 9mm(the front layer that is a diffusion barrier to the B2), and then during about 30 minutes and every 5 minutes, add Riboflavin drops 0.1% over the stroma (the layer below the epithelium), while the cornea is radiated with a 370nm wavelength UV-light lamp.
This stiffens the cornea, flattens the cone, decrease its thickness and improves its resistance against degrading enzymes.
after the procedure, an antibiotic ointment is applied and analgesics prescribed, the process is completed by reepithelization of the corneal epithelium that takes between four to six months after the surgery.
Epi-on crosslinking
The epi-on procedure avoids the removing of the epithelium and removes most of the complications like infections, slow healing a haze that results from the more aggressive epi-off procedure.
This uses substances that increase epithelium permeability looking to improve riboflavin penetration in the stroma.
It is still in debate if is better to remove the epithelium or not before the UV-light irradiation.
Biography:
Keratoconus surgery and Crosslinking. Roberto Pinelli MD, Antonio Leccisotti MD Ph.D., 2009 Jaypee Brothers Medical Publishers.
1 Fasting and Eating for Health, Joel Fuhrman, MD. p65.