Corneal Collagen Cross-Linking
Did you know? The technique of cross linking was first identified by skin specialists who discovered that collagen cross linking could be used to strengthen sagging skin. This concept was then utilized by eye doctors in ’93 in Germany. Whoever said piggybacking was bad?
Corneal Collagen Cross Linking (CXL or C3R) is a technique that aims to strengthen the chemical bonds in your cornea (the transparent front surface of your eye) by the application of riboflavin (a type of Vitamin B2) followed by treatment with Ultraviolet A light.
1. Epithelium Off: Here, the thin layer covering the surface of your eye is removed. This helps the riboflavin to penetrate faster.
2. Epithelium On: Also called trans epithelial corneal cross linking, the corneal epithelial surface is left intact. This requires a longer riboflavin loading time.
When is the Corneal Collagen Cross Linking surgery performed? (Indications)
The aim of this technique is to stop the progression of irregular changes in the shape of your cornea which is known as ectasia. These changes may be thinning or increase in curvature of the cornea.
• Keratoconus (a degenerative condition in which the cornea becomes thin and conical in shape)
• Corneal weakness (ectasia) after LASIK
• Pellucid Marginal Degeneration (a degenerative condition of the cornea in which there is thinning of the cornea)
• Corneal Ulcers (a sore on the surface of your cornea)
This technique has also been used in combination with other procedures like intracorneal ring segment implantation (called Intacs) and limited topography guided photoablation (where lasers are used to destroy tissues).
• Thin corneas (Less than 400 microns with conventional C3R)
• Previous infection with Herpes Virus (as it may get reactivated)
• Simultaneous Infections
• Severe scarring or opacities in the cornea
• Autoimmune diseases (diseases where your own immune system attacks your cells)
• History of poor healing of wound
• Severe diseases involving the eye surface like dry eyes
Studies have found that 99% of patients will achieve improvement or remain stable as regards the corneal shape after CXL.
Corneal Cross Linking is not a cure for keratoconus. It just aims to slow or stop the progress of the disease.
After the procedure, you will be required to continue wearing spectacles or lenses.
Before the procedure, your doctor will measure the thickness of your cornea and assess your visual acuity. A mapping of your cornea called corneal topography may also be done.
The corneal collagen cross linking lasts for 15 - 20 minutes using newer techniques.
You are first given anesthetic drops. A lid speculum is used to hold your eyelids in place.
If you are undergoing epithelial-off cross linking, you will be placed in a reclining position to remove the epithelial layer. Riboflavin drops will then be given at intervals of 1-5 minutes until the riboflavin can be seen in your eye’s anterior chamber.
If it is an epithelial-on cross linking, you are put in a reclining posture and the riboflavin drops are placed.
After the adequate time has passed, your surgeon will determine whether enough riboflavin is there. Then, the corneal thickness is checked.
This is followed by application of UV light.
Then, a bandage contact lens may be placed. Anti-inflammatory and Antibiotic drops will be prescribed to you.
Temporary swelling of a layer of the cornea
Infection of the cornea
Inflammation of the cornea (called diffuse lamellar keratitis)
Temporary or permanent haze