A cornea transplant is a surgical procedure in which part or a patient’s entire cornea is removed and replaced with donor material from a cadaver, usually obtained through an eye bank or an organ and tissue bank. The cornea transplant is one of the most widely performed transplant surgeries in the world, and also one of the oldest, with documented successful cases dating to the early 1900s. This procedure is generally recommended when a patient has severe corneal damage, vision problems, or inflammation of the cornea which cannot be resolved.
In a basic cornea transplant, a “button” of material is removed from the patient's cornea and replaced with a corresponding button taken from a cadaver. The donor cornea is then stitched in place. It is also possible to perform partial transplants which only involve the upper layers of the cornea, or a procedure known as a deep lamellar transplant, in which one of the lower layers of the cornea is removed through a slit along the side of the cornea, leaving the upper layers of the patient's cornea intact.
This procedure is performed by an ophthalmologist, and can be done under general anaesthesia or with a local anaesthetic and sedation. The healing process is quite prolonged, usually taking a year or more. In the early stages of healing, the patient needs to wear eye protection to avoid physical trauma, and take steroids to resist rejection. Vision is typically very blurry at first, gradually resolving over time, and the stitches can be removed in three to 18 months, depending on how well the patient heals. Transplant rejection can occur in as many as 18% of cases.
Many people who have received a cornea transplant develop astigmatism, which needs to be corrected to allow the patient to see clearly. The patient may wear glasses to address the issue, and it is also possible to wear specially designed contacts to address the astigmatism. However, fitting contacts can be challenging after transplant, and this may not be an option for all patients, so patients should be prepared to wear glasses after a cornea transplant.
Also known as penetrating keratoplasty or corneal grafting, a cornea transplant can make a huge improvement in a patient's quality of life. Candidates for transplant will be given a thorough eye exam and educated about the potential risks and aftercare involved with a cornea transplant. If a patient is a good candidate, he or she will be put on a waiting list, and when a donor cornea becomes available, the surgery can be scheduled.
Descemet's stripping endothelial keratoplasty (DSEK) is another type of corneal transplant surgery. A surgeon uses specialised instruments to enter the eye through a tiny incision in the cornea. The back section of the cornea, which is called Descemet's membrane, is stripped away and replaced by a piece of healthy graft tissue.
DSEK does not require stitches, and therefore results in far fewer astigmatism problems afterwards. There are fewer follow up exams after the surgery, and patients generally recover vision much faster. Some believe that DSEK transplants results in fewer transplant rejections than with more conventional transplants.
Lamellar keratoplasty (LK) is a type of corneal transplant surgery that involves removing and replacing only the diseased or scarred outer layers of corneal tissue and replacing them with a new "flap" of donor tissue. The procedure is more challenging to perform than a PK surgery, but the risk of tissue rejection and infection are less. If stitches are required, they can usually be removed within a few weeks and visual recovery can be very rapid. LK surgery is only suitable for conditions involving the very outermost layers of the cornea.
Epikeratophakia is a rarely used type of corneal transplant surgery that involves suturing the donor cornea tissue directly onto the surface of the existing cornea. Only the extremely thin cell layer on the outside of the patient's cornea is removed. The procedure can be reversed, and there is no permanent damage to the patient's cornea. This surgery is not widely used because the use of contact lenses can generally achieve the same results.