What is a cornea?
The cornea at the front of the eye is the clear outer surface. This protects the eyes from infections, ultraviolet light and other particles. Working with the eye lens, the cornea focuses light which enters the eye so that vision can be clear.
The cornea is formed of three main layers of tissue, with additional two layers which are thin between these layers.
What is cornea transplant surgery?
A corneal transplant is a medical procedure to substitute a donor’s cornea with tissue. This procedure is known as Keratoplasty.
Why is it needed?
For restoration of vision in patients with damaged cornea, corneal transplant is carried out. A corneal transplant may also relieve pain or other signs and symptoms related to corneal disease.
A variety of problems with a cornea transplant can be treated including:
Preparation before surgery?
Prior to the surgery, the patient will undergo:
- Getting a donor cornea
Deceased persons are the major source of cornea. The waiting period for getting a donor cornea is less in comparison to getting other organs. This is due to the fact that many persons voluntarily give their consent for eye donation posthumous.
Corneas can not be used by donors with various disorders, such as other diseases in the central nervous system, allergies, and previous eye surgery or eye problems, or by people who have died from an unexplained cause.
Procedure to transplant a full thickness cornea
The patient sedates under local anesthesia which numbs the eyes. The patient will be awake but will not have the feeling of any pain.
Penetrating keratoplasty: The complete diseased cornea is cut and a small button-sized disk of corneal tissue is removed. This is accomplished by the use of trephine (cookie cutter). Then the donor cornea is cut exactly to the size of the diseased tissue and placed in the opening. Fine suturing (stitching) is done to keep it in place. Suture removal is done at follow-up.
Keratoprosthesis (artificial) is inserted in some patients who are not eligible for transplant from a donor.
Procedures to transplant a portion
A full-thickness transplant isn’t necessarily the most effective treatment for some forms of problems. Those types of procedures are:
- This technique extracts diseased tissue, including the endothelium, from the back corneal layers along with the Descemet membrane. In majority, only one-third of damage is replaced by donor tissue. A newer type of procedure known as Descemet membrane endothelial keratoplasty uses a much thinner layer of donor tissue, which makes this process more challenging.
- The severity of the damage to the organ defines which form of anterior lamellar keratoplasty treatment will be done. Only the front layers are replaced in superficial anterior lamellar keratoplasty , leaving the healthy endothelium intact. In deep anterior lamellar transplant, an incision is made of the eyeball to allow the front and middle layers to be removed.
After the Procedure
The patient is sent home on the same day of the surgery and is given an eye patch to keep on for nearly 4 days. Antibiotic eye drops and other medications will be prescribed to prevent injection and graft rejection. The patient is given advice about follow-up.
Cornea transplant is a reasonably safe operation. Nevertheless, it carries a small chance of severe complications, like:
In a few instances, the body’s immune system can erroneously attack the donor cornea. This condition is called graft rejection, which may require medical treatment and in case of complete failure, another transplant. Rejection has been reported in nearly 10 percent cases of transplant surgery.
Majority of the patients can expect partial restoration of vision after the surgery. This restoration depends on the patient’s clinical condition and the reason for which this surgery was performed.
The possibility of graft rejection and infection lingers on for years, so the patient needs to have a regular follow-up with the surgeon as per the schedule.
The patient’s vision improves over a long period of time, which is very poor at the initial stages of surgery, but gradually shows improvement. The vision stabilizes once the outer layer of the cornea is healed completely. After checking for the vision, the patient may be prescribed spectacles for vision correction. And in case of unevenness of cornea also called astigmatism, the surgeon may correct this by tightening some sutures and releasing some of them.
When to contact your doctor
Generally the sutures are removed on the follow-up visit, but some sutures may remain in place for a long period of time or some sutures may not at all be removed.
Immediately contact the transplant surgeon, if you notice:
Special instructions for patients
The patient is explained about the need to take care during moving in and around the house and prevent the fall. Bathroom safety is of utmost importance. Western types of toilets are more preferable. In the case of Indian toilets, raised seats can be used. Care should be taken so that the patient does not slip inside the bathroom.