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Penetrating keratoplasty (PK) is a surgical procedure in which the diseased or damaged corneal tissue of a patient is removed and replaced with healthy corneal tissue from a deceased donor. The cornea is the clear tissue on the front of the eye that allows light to pass through to the back of the eye. If the cornea becomes cloudy or scarred, vision may be impaired.
Several diseases can damage the cornea and leave the patient with blurred vision. Keratoconus is a disease in which the cornea becomes thin and develops an irregular cone shape. The eye doctor, or ophthalmologist, may try to restore the patient’s vision with contact lenses or eyeglasses. If those options don’t help the patient, the eye doctor may decide to perform the penetrating keratoplasty surgery.
Herpes simplex virus can infect the cornea and cause scarring and impaired vision. As the patient’s immune cells invade the cornea to fight off the virus, the cornea may become cloudy. Antiviral eye drops may be used to treat the virus and corticosteroid eye drops may be used to inhibit immune cells from entering the cornea. If the cornea is damaged, the patient may need to have a penetrating keratoplasty to replace the cornea.
Penetrating keratoplasty, also known as a corneal transplant, is usually done on an out-patient basis. The patient will be given either a general anesthetic, or a sedative along with a local anesthetic. During the procedure, the patient’s eye will be held open with a clamp. The ophthalmologist will then use a surgical tool called a trephine to cut a circle in the cornea. Damaged tissue is removed and replaced by a cornea harvested from an organ donor.
The round piece of donor cornea is sutured into place in the recipient’s eye. Corneas harvested from organ donors are stored at an eye bank and are carefully evaluated to make sure the tissue is clear. The organ donors are also screened for hepatitis and HIV to ensure that those diseases are not passed on to the recipient.
After the penetrating keratoplasty surgery, the patient will need to wear an eye patch for a few days to avoid any damage to the new cornea. The eye doctor will also prescribe antibiotic eye drops to prevent any infection. Corticosteroid eye drops may be needed to prevent any immune cells from entering the new tissue.
Stitches in the cornea are easily removed in the eye doctor’s office and may be removed up to one year after the surgery. The patient’s vision should improve gradually over several months. Complications such as pain or blurred vision should be reported to the ophthalmologist immediately to prevent rejection or damage to the new cornea.