Undergoing the Corneal Transplant– Types of Transplant and procedure
Many donors pledge their eyes during their lifetime itself but in case if this has not been done, then the cornea can be taken after family consent also. The cornea is extracted from a brain-dead donor, and there is a 24-hour window after the donor’s death when the cornea can be procured and safely stored in a conducive environment. Corneoscleral tissue or Cornea can be stored for up to 14 days after the procurement, thereafter it will expire and will have to be discarded. This fact makes corneal transplantation different from other organ transplants, in which procurement is awfully restricted due to insufficient time and availability of a receiver.
The surgery takes one to two hours with another one or two hours to be spent in the recovery room. Eye drops and a sedative are administered to the patient for relaxing. Depending upon certain factors including age, medical condition, and the eye disease either local or general anesthesia is given to the patient. Anesthesia is injected around the eye in order to prevent pain and also to keep the eye muscles from moving. The eye is held open with a lid speculum or by another method during surgery.
- Penetrating Keratoplasty – PK (Replacing the entire cornea)
A microscope is used during the surgery. The surgeon uses a trephine – a cutting instrument and removes a small, round disc of tissue from the center of the eye. The corresponding disc taken from a donor's eye to fit is placed and sewn with an ultra-fine thread. The thread is removed once the eye heals completely.
- Deep Anterior Lamellar Keratoplasty – DALK
This is a combination of several techniques where diseased layers of the cornea are selectively replaced, and the healthy layers are left in their places. DALK is performed on corneas which have the anterior or the superficial part diseased or damaged with the deeper layers being healthy. So, only the front part of the cornea is removed, and the endothelial cells are not replaced. This reduces the risk of rejection, and fewer steroid drops may be required after surgery. Another advantage of DALK is that the eye is less prone to injury since it is allowed to retain some of its structural strength.
- Endothelial Keratoplasty – EK
If only the deep layers – the corneal endothelium of the cornea are diseased and the superficial layers are healthy, then endothelial keratoplasty is performed leaving the superficial layers intact. The surgery does not need any sutures and hence, recovery time is less with less induced astigmatism.