Corneal cross linking is used to treat a condition called Keratoconus.
Keratoconus is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than the more normal gradual curve. Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light all often reported by the person.
It is estimated that eventually 21% of the keratoconus patients require surgical intervention to restore corneal anatomy and eyesight.
How does Corneal Cross Linking work ?
C3R – Corneal Crosslinking (collagen) with Riboflavin has been proven to strengthen the weak corneal structure by increasing collagen crosslinking, which are the natural “anchors” within the cornea. These anchors are responsible for preventing the cornea from bulging out and becoming steep and irregular, a consequence of advanced Keratoconus.
This procedure is best done in early stages of keratoconus where there is documented progression of keratoconus.
How the corneal cross linking done ?
The C3R treatment is performed in just 30 minutes. During the treatment, riboflavin eye drops are applied to the cornea, which is then activated by ultraviolet light or UV light.
Cross linking is done in the operation theater of an eye hospital with all necessary aseptic precautions, however it is not really an eye surgery.
The cornea which is the front transparent structure of the eye is first anaesthetized by using numbing eye drops. The front most surface of the cornea (epithelium) is disrupted by scraping the cornea and removing this superficial layer. Then Riboflavin-Vitamin B2 drops are placed in the eye every few minutes. After this the UV light is directed toward the cornea. This light is directed on the cornea for about 30 minutes. The yellow pigment of the Riboflavin absorbs the Ultraviolet light, increases the amount of collagen cross-linking in the cornea and strengthens the cornea. Once this 30 minute procedure is completed, a soft bandage contact lens will be placed in the eye and antibiotics will be instilled. The bandage contact lens is inserted because as mentioned earlier the front most layer of the cornea is peeled off. A cornea without this front layer can be painful a few hours after this procedure. However, with the bandage contact lens in place the pain becomes almost nil. The contact lens will be removed in one or two days.
The cornea increases in rigidity soon after the procedure, although the process of cross linking continues on for a period of a few days afterwards. The effect on corneal shape takes longer but flattening does not occur in all eyes that have had treatment. A satisfactory result will be arresting the progress of keratoconus.
C3R causes the collagen fibrils to thicken, stiffen, and crosslink & reattach to each other, making the cornea stronger and more stable & halting the progression of the disease
Ultraviolet light used in this procedure is not harmful to the eye in measured doses. Ultraviolet C light (in sunlight) is potentially harmful. The Light emitting diodes used in the C3R device is of a wavelength that is not harmful. Furthermore, light emission is carefully measured and calibrated prior to each treatment. There is also a self diagnostic check on the device which prevents use in case of a malfunction. There have been concerns about toxicity to the retina (at the back of the eye) however the Riboflavin pigment in the cornea and front of the eye absorbs the Ultraviolet light and in effect stops the light from being transmitted to the retina.
Advantages Of Cross Linking
- No follow up sittings required
- No need for admission
- Stops the progress and causes regression of disease
- Does not need eye donation as in corneal transplant
- No major precautions
- No injections or stitches
- No incisions as in Intacs or Corneal ring segments
- Quick recovery with short follow up
What does cross linking not do
What happens if corneal collagen cross linking with riboflavin is not done in time ?
Frequently Asked Questions
The procedure per se does not really have any risks. Patient selection is very important and this procedure cannot be done in very thin cornea. Sometimes we instill distilled water to thicken the cornea prior to using the ultraviolet light.
Sometimes patients may complain of a slight haze post the procedure and this too gradually subsides.
The procedure per se is not painful. Patients may experience itching and irriation and watering post the procedure for a few days. We expect patients to instill certain eye drop post the procedure.