PK or Penetrating Keratoplasty is a full thickness corneal transplant. This type of corneal transplant is performed when both the front and back layers of the cornea are abnormal. This technique is best for conditions that involve clouding throughout the entire cornea or for conditions such as keratoconus where the cornea's shape is severely distorted. Advantages of this type of transplant include replacement of all layers of the cornea, a long successful track record, and a fairly straightforward surgery. Disadvantages include a relatively long visual recovery period, a large corneal incision with many sutures and a possible high degree of astigmatism post-operatively. Corneal transplantation is performed using local or general anesthesia in the operating room.
In this surgery, all five layers of the central 8-9 mm of the normally 12 mm diameter cornea are removed using an instrument that looks like a miniature round “cookie cutter” called a trephine. The diseased cornea is replaced with a clear donor cornea cut with a trephine of the same or similar size. The new donor cornea is held into place by numerous sutures…most times 16-24 fine nylon sutures that are 1/4 the size of a strand of hair. This outpatient procedure generally takes between 30 and 60 minutes to perform but healing can take up to a year with very gradual recovery of best vision. Since an incision is made through the entire cornea, the strength of the eye is compromised and the eye is more vulnerable to trauma or injury.
What to Expect on Your Surgery Day
On your surgery day, you may eat a light meal six hours before your arrival time, if you choose. Take your medications as prescribed by your medical doctor. The outpatient surgery is performed at a state-of-the-art Ophthalmic Ambulatory Surgery Center. The actual surgery takes 30 to 60 minutes, but plan on being at the center for a couple of hours. Surgery is usually done under local anesthetic. While lying flat on a surgery bed, you will be given sedation medication and your eye will be completely numbed by a local block. A sterile drape is placed over your face including both eyes. During surgery, you will be unable to move, blink, or see very much out of your eye (faint shadows or dim light may be seen). You will be awake but relaxed throughout the procedure. If you have any discomfort, please inform Dr. Cavanaugh or the Anesthetist.
Post-op Care of Your Transplant
In the first few days, you may feel a foreign body sensation (a scratchy feeling) in the eye from the incision and tiny sutures. Discomfort should go away in one to two weeks. In most cases, stitches are removed only if the doctor feels it is necessary to control healing. Your vision will be blurry after surgery due to swelling and astigmatism in the new cornea and may last several months while the cornea heals. Astigmatism occurs when the cornea is not perfectly round or spherical and can be caused by the stitches or asymmetrical healing. As the eye heals and sutures are removed, the cornea will be more round and clear with an associated gradual improvement in vision. The doctor will not recommend new glasses until he believes there is sufficient healing. Best vision generally takes three to six months but can take one year or more.
During the healing process, you will return to see the doctor frequently. Do not be concerned with visit frequency as transplants require close monitoring. At each visit, you will be given progress updates, medication and treatment instructions. The doctor and staff answer any questions or concerns you may have and schedule your next appointment.
Risks of Transplant Surgery
Just as there may be risks and hazards in continuing your present condition without treatment, there are also risks and hazards related to the performance of your surgery. Your physician will review the particular risks relating to your health and the condition of your eye. The complete list of surgical risks is beyond the scope of this website and can be found in the Corneal Transplant consent form you will receive prior to surgery. Some of the potential risks of a corneal transplant include, but are not limited to the following:
- Hemorrhage or bleeding
- Problems with healing
- Anesthesia complications
- Complications of surgery in general
- Risks associated with any eye surgery: Glaucoma, Cataract Formation, Retinal Detachment
- Corneal transplant rejection
- Displacement of donor disc
- Recurrence of pre-existing disease
- Induction of astigmatism
Click here to read the differences between a full thickness and DSAEK corneal transplant.