What is Collagen Cross-Linking of the Cornea?
Collagen cross-linking of the cornea is a treatment for keratoconus. It is involves using an ultraviolet light source and a photo sensitizer agent that is applied to the cornea. This strengthens the structure of the cornea. This treatment can also be used for others forms of corneal ectasia.
Method of Action for Cross-Linking
The research for corneal cross-linking was started in Europe at the University of Dresden. In pig and rabbit eyes riboflavin was applied to the corneas and ultraviolet light was used to promote cross-linking in the cornea. The corneas were shown to have increased collagen cross-linking making the corneas stronger and more resistant to degradation.
What is Keratoconus?
Keratoconus is a disease of the cornea where the cornea begins to thin in one area and starts to protrude in that area. This leads to blurred vision due to the irregular changes in the shape of the cornea. As it progresses, the vision becomes more blurred and eventually it cannot be corrected with glasses. People then have to wear different types of contact lenses. It can continue to progress where a person has trouble wearing contacts lenses and may need surgery to correct their vision. Cross-linking is a less invasive treatment for keratoconus.
Who is a Good Candidate for Collagen Cross-Linking?
People who have keratoconus or other forms of cornea ectasia may be candidates for collagen cross-linking. The cornea ectasia should be still progressing with changes in vision and corneal shape. At this time, collagen cross-linking is still under investigation but approval is expected soon. It has been in use in other parts of the world for some time.
Contraindications of Collagen Cross-Linking
Autoimmune and collagen vascular disease
Corneal thickness of less than 400 microns
History of herpes infection
Significant dry eye syndrome
Surgical Procedure for Collagen Cross-Linking
Topical anesthetic eye drops are instilled into the eye. The epithelium is removed in many cases. Riboflavin 0.1% is instilled onto the eye 1-5 minutes for 15- 30 minutes. Once the riboflavin has penetrated the cornea and can be seen inside the anterior chamber of the eye, the patient is placed where the ultraviolet light is very close to the cornea. The light is left on for 30 minutes.
Complications of the Procedure
Swelling of the cornea which is temporary
Temporary or permanent haze of the cornea
Infection or corneal ulcer
Sterile infiltrates in the cornea
Collagen cross-linking holds great promise in the treatment of keratoconus and other corneal ectasia diseases. It is less invasive than current surgical procedures for keratoconus.