What is Keratoconus?
Keratoconus is a non-inflammatory eye condition in which the typically round-vaulted cornea progressively thins and weakens, causing the development of a conical swelling resulting in a visual abnormality of the cornea. This can lead to significant visual impairment.
Keratoconus usually first appears in people who are in their late teens or early thirties and may progress for 10-20 years, then slow down or stabilize. Each eye can be affected differently. In the early stages of keratoconus, people may experience:
- Slight blurring of vision.
- Distortion of vision.
- Increased sensitivity to light.
The cornea is responsible for focusing most of the light that enters the eye. Therefore, corneal abnormalities, such as keratoconus, can have a significant impact on the way a person views the world, making difficult simple tasks (eg driving a car or reading) difficult.
- It can lead to significant vision loss and
- It can lead to corneal transplantation in severe cases
What is “Cross-Linking”(C3R/CXL corneal junction)?
Cross-linking is a minimally invasive procedure that combines the use of UV-A light and riboflavin eye drops to add stiffness to corneas that have been weakened by disease or refractive surgery. It is the standard treatment worldwide for keratoconus and corneal extension after refractive surgery.
- Creates new collagen bonds in the cornea, causing control of corneal curvature
- It results in the shortening & thickening of the corneal collagen fibrils
- Leads to hardening of the cornea and stabilization to prevent the development of keratoconus
Riboflavin (vitamin B12) is important for the body’s growth, production of red blood cells and helps release energy from carbohydrates. Food sources include dairy products, eggs, green leafy vegetables, lean meats, legumes and nuts. Breads and cereals are often fortified with riboflavin.
Under the conditions used for corneal collagen cross-linking, riboflavin 5-phosphate, vitamin B2, acts as a light enhancer that allows the cross-reaction.
Ultraviolet A (UV-A)
UVA is one of the three types of invisible light rays emitted by the sun (along with ultraviolet B and ultraviolet C) and is the weakest of the three.
An ultraviolet light source is applied to irradiate the cornea after it has been impregnated with riboflavin photo-enhancement solution.
This crosslinking process hardens the cornea by increasing the number of molecular bonds or crosslinkings in the collagen.
How exactly is the corneal cross linking technique performed?
The treatment is performed under local anesthesia (with drops of anesthetic on the cornea).
- remove (or not) partially the corneal epithelium (and instill vitamin B12 drops
- then the eye is irradiated with ultraviolet UV-A, during which riboflavin B12 is still instilled
- usually at the end an antibiotic ointment or drops are applied as well as a protective contact lens, in order to avoid injury at night, until the cornea is completely restored.
It is the only treatment with extremely high success.
It aims at the real cause of the keratoconus, in order to stop the progressive thinning of the cornea.
This maximizes the chance of corneal transplantation (keratoplasty).
Patients will continue to use glasses or contact lenses
In some cases, excimer laser treatment and use can be done
Where does Cross-Linking apply?
In patients over 14 years of age who have been diagnosed with progressive keratoconus or have corneal extent after refractive surgery.