What is Corneal Collagen Cross Linking?
Corneal cross linking is a new, minimally invasive surgical procedure used to strengthen the cornea. The aim of cross linking is to slow down or stop the progression of corneal thinning caused by diseases such as keratoconus or other forms of corneal ecstasia. This is done by using riboflavin (Vitamin B2) eye drops and UVA light on the cornea which work together to make collagen bonds in the cornea stronger. As a result, the cornea increases its strength almost 300% causing it to become stiffer thus, stabilizing the corneal contour.
As for now, cross linking is the only treatment that can stop diseases like keratoconus from getting worse. The procedure is most effective when done in the early stages of the disease, before the cornea has become too misshapen and vision has been compromised. Therefore, it is vital that teenagers and young adults with increasing astigmatism and short sightedness be screened for keratoconus. Early keratoconus can be detected with corneal topography and if present, treatment with collagen cross-linking can be initiated to halt progression of the disease and vision loss.
The procedure is fairly simple and begins with your doctor giving you eye drops to numb the eye. In most cases, the surface cells (epithelium) of the cornea is removed to aid riboflavin absorption. This is followed by application of riboflavin eye drops onto the cornea for 30 mins before UVA light is shone onto the eye for another 30mins (along with continued riboflavin eye drops). At the end of the procedure, a soft CL (bandage Contact lens) is placed onto the cornea and the patient is given eye drops to use at home.
After the procedure, your eyes might feel, gritty, dry or painful. This is common as the surface cells take a few days to heal. You can speed healing by using the eye drops given to you by your doctor. This reduces the inflammation and lubricates the eye. Do not rub your eyes as this may cause further damage. Use sunglasses as your eyes may be sensitive to light and do get enough sleep.
Besides progressive keratoconus, crosslinking is also useful in other forms of corneal thinning. This includes pellucid marginal degeneration and iatrogenic keratectasia after refractive surgery. It has also been used successfully in some cases of corneal infections not responding to conventional therapy.
Corneal cross linking is associated with a low rate of complication. However, as with any other surgical procedure, there are risks involved with cross linking. Because collagen cross linking includes the removal of the corneal epithelium (the cornea’s surface cells), the procedure may result in epithelial haze and delayed epithelial healing. Other risks may include an infection of the cornea, herpetic keratitis, corneal scarring and blurred vision. Your doctor will discuss the risks and benefits with you in more detail prior to surgery.
Following the procedure, your doctor will give you medication to hasten re-epitheliazation, reduce pain and reduce the risk of infection. You may notice fluctuations in your vision however, this will stabilise. Once the cornea surface has healed you will be able to go back to your spectacles or contact lenses. Although the main aim of corneal cross linking is to prevent progression, some patients may experience an improvement in vision. We generally recommend patients wait 2-3 months after treatment if they plan to make new spectacles in order to ensure a stable refraction