Keratoconus and surgery for a Corneal Graft
Keratoconus is a disease of the cornea which can result in blurry vision and ghost images. If Keratoconus progresses it can cause a thinning of the cornea if it is not arrested through corneal collagen cross-linking. If the condition progresses unabated then the eventual treatment will be a corneal graft.
If you have Keratoconus then the front transparent surface of your eye thins with the result that your cornea distends and droops into an irregular ‘cone’ shape. This distortion results in your eye being unable to create a single focus point on your retina at the back part of your eye.
These multiple focus points result in blurry vision and sometimes a kind of double, treble or even quadruple images which s called ‘ghosting’.
Between one in five hundred and one in two thousand people are diagnosed with Keratoconus. Initially, some form of contact lens will be sufficient to correct their vision. If the condition continues to progress the vision will become more distorted so that contact lenses are no longer able to cope effectively with the disparity in the corneal shape.
For a small number of people with the condition, the cornea will become so thin, so distorted and maybe too scarred, for contact lenses to work.
Corneal Collagen Cross-linking is a very effective procedure that can stabilise the cornea and prevent progression of the keratoconus. However, some patients seek this treatment too late or are unable to afford it privately. In these cases patients may need to revert to a Corneal transplant.
There are two basic types of Corneal transplant. In this article we will describe the Full Thickness Transplant or Penetrating Keratoplasty. The normal human Cornea is about 0.5 mm thick. Keratoconus causes the cornea to thin. If it thins beyond 0.4mm it becomes difficult to undertake other forms of surgery like Corneal Collagen Cross-linking.
An area of about 7mm in diameter is removed from the cornea and replaced with corneal tissue from a donor eye. The replacement cornea is stitched on using a number of different types of sutures placed around the transplanted cornea tissue.
This operation is usually carried out under a general anaesthetic and sometimes involves an overnight stay in hospital.
After the operation drops have to be administered into your eye for several weeks, or maybe months. These drops normally comprise an antibiotic to ward off any infection and a steroid based drop to help prevent rejection.
Regular check ups are normally carried out in the weeks immediately post operation and, at some point, the surgeon may decide to selectively remove some stitches to help to re-shape your eye.
It can take twelve to eighteen months for the cornea to reach the best shape it can. It is often the case that contact lenses may still be needed to correct your vision.
These transplants are successful in many cases and patients get a significant improvement in uncorrected and corrected vision compared with what they would have had with progressive keratoconus.
Rejection rates are low and can normally be treated with eye drops if they do occur.
It’s best not to opt for a transplant until all other avenues have been exhausted, including corneal collagen cross-linking. You can’t go back after a transplant and the recovery time is significant.
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John Andrews is witness to some of the leading developments in laser eye surgery and Keratoconus treatment through his involvement in Accuvision Laser Eye Care Clinics. He meets with patients from around the world who travel to Accuvision for its leading edge technology, treatments and the outstanding results they are able to safely deliver.
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