The cornea is a window of transparent tissue at the front of the eyeball. It allows light to pass into the eye and provides focus so that images can be seen. Various diseases or injury can make the cornea either cloudy or out of shape. This prevents the normal passage of light and affects vision.
The cornea consists of 5 layers, 2 outer thin ones (epithelium and Bowman’s), a thick central one (stroma), and 2 thin inner ones (endothelium and Descent’s layer). A number of different corneal transplants (keratoplasty) are available depending on the specific diagnosis. These include:
- All layers of the central cornea are replaced. This is used to treat corneas that are scarred or have an abnormal shape.
-Endothelial Keratoplasty (DSAEK and DMEK) - treating conditions where the inner endothelial layer of the cornea is not functioning. The transplant is folded up and injected into the eye before being unfolded and held in place by an air bubble.
-Deep anterior lamellar keratoplasty (DALK) - the central epithelium, Bowman’s and stroma are replaced leaving the patient’s endothelium and Descemet’s layers untouched. This dramatically reduces the risk of rejection seen with a penetrating keratoplasty.
Penetrating and deep anterior lamellar transplants take 1-1.5 hours and can be done under general or local anaesthesia. Usually 16 stitches are required to hold the transplant in place. The stitches are removed between 9 and 18 months after the surgery. Patients normally need glasses or a contact lenses to achieve the best possible vision after the stitches are removed. With endothelial keratoplasty the surgery is quicker, taking 45 minutes, and normally performed under local anaesthesia. Typically only 1-2 stitches are used which are removed after about 6 weeks.
After the operation
Patients having penetrating and deep anterior lamellar keratoplasty are normally reviewed after the operation and then at 1 week. Endothelial keratoplasty patients typically have to lie on their backs for an hour after the surgery. This allows the air bubble to push the graft into place. Patients are checked after the hour and then again the following day. Early checks are crucial to check that the graft is sitting in the correct position.
Am I suitable?
The type of transplant that a patient needs depends on the condition affecting the eye.
- Keratoconus-Penetrating or deep anterior keratoplasty
- Fuchs’ endothelial dystrophy-DMEK
- Pseudophakic bullous keratoplasty-DMEK
- Previous failed penetrating keratoplasty-DSAEK/DMEK
- Corneal scar/trauma-Penetrating keratoplasty
|3rd or higher number regraft||0-50|
|4 quadrants of blood vessels||0-50|
|Inflammation at time of surgery||0-50|
|Severe ocular surface disease||0-50|
|Grafts greater than 10mm||0-50|