Corneal Transplantation

What is corneal transplantation?

If your cornea is damaged and cannot be healed or repaired, your ophthalmologist may recommend a corneal transplant, also known as corneal grafting or penetrating keratoplasty (PKP). This procedure replaces a diseased cornea with a clear, healthy cornea from a human organ donor.

Human donors are individuals who choose to donate their corneas after death to those in need. All donated corneas are thoroughly tested to ensure they are healthy and safe for use.

There are different types of corneal transplants. In some cases, only the front and middle layers of the cornea are replaced (DSEK). In others, only the inner layer is removed (DMEK). Sometimes, the entire cornea needs to be replaced (penetrating keratoplasty, or PKP).

What is penetrating keratoplasty (PKP)?

Penetrating keratoplasty (PKP) is the most common, traditional form of corneal transplantation. PKP is a full-thickness corneal transplant. It was first developed over 100 years ago. Although over 100,000 PKP procedures are performed worldwide each year, some estimates report that there may be 10 million people affected by various disorders that would benefit from corneal transplantation.

In the United States, the cost is usually covered in whole or in part by Medicare and health insurance. Reimbursement depends on your individual healthcare provider.

Why do you need a cornea transplant?

A corneal transplant is done for a variety of conditions that lead to poor vision. These include Fuchs’ corneal dystrophy, bullous keratopathy, herpes keratitis, and sometimes ocular trauma. They are also sometimes used to relieve pain in a damaged or diseased eye, or to treat emergencies such as severe infection or damage. Indications for corneal transplantation include the following:

Optical: To improve visual acuity by replacing the opaque host tissue with clear, healthy donor tissue. The most common indication in this category is pseudophakic bullous keratopathy, followed by keratoconus, corneal degeneration, keratoglobus and dystrophy, as well as scarring due to keratitis and trauma.
Tectonic/reconstructive: To preserve corneal anatomy and integrity in patients with stromal thinning and descemetoceles, or to reconstruct the anatomy of the eye, e.g., after corneal perforation.
Therapeutic: To remove inflamed corneal tissue unresponsive to treatment by antibiotics or anti-virals.
Cosmetic: To improve the appearance of patients with corneal scars that have given a whitish or opaque hue to the cornea.

How is a corneal transplant done?

On the day of the surgery, you will arrive at the outpatient surgery center, where the procedure will be performed.

You will undergo a brief physical examination by the surgical team and then be taken to the operating room. In the operating room, you will lie down on an operating table and either be given general anesthesia or local anesthesia and a sedative.
With anesthesia induced, the surgical team prepares the eye to be operated on and drapes the face around the eye. An eyelid speculum is placed to keep the eyelids open, and a lubricant is applied to the eye to prevent drying. A metal ring is then stitched to the sclera, providing a base for a trephine.
A trephine is then placed over the cornea and is used by the surgeon to cut the host cornea. The trephine is then removed, and the surgeon cuts a circular graft (a “button”) from the donor cornea. Once this is done, the surgeon returns to the eye and removes the host cornea.
The donor cornea is then brought into the surgical field and maneuvered into place with forceps. Once in place, the surgeon will fasten the cornea to the eye. The surgeon finishes up by reforming the anterior chamber with a sterile solution injected by a cannula, then testing that it’s watertight by placing a dye on the wound exterior.
With the metal ring removed and antibiotic eyedrops placed, the eye is patched, and you will be taken to a recovery area while the effects of the anesthesia wear off. You may go home following this and see the doctor the following day for your first post-operative appointment.

How safe is cornea transplant?

Cornea transplant is a relatively safe procedure, with about a 90% success rate, and the rate of rejection is only about 8%. Rejection episodes can often be controlled with topical steroid drops.

Graft failure can occur at any time after corneal transplantation, even years or decades later. The causes can vary, though it is usually due to a new injury or illness. Treatment can be either medical or surgical, depending on the individual case.

Occasionally, there are problems with sutures, which can loosen, lead to infections, or cause astigmatism. The astigmatism after traditional corneal transplant surgery can be significant enough that eyeglasses alone may not provide adequate vision. These patients may ultimately require contact lenses or additional surgery to reduce or eliminate the astigmatism.

Because the wound is full-thickness and 360 degrees, the corneal transplant wound is not as strong as a normal wound. It is at risk of rupturing or breaking open from a mild or incidental blow to the eye, even several years after the surgery.

While the cornea is avascular, there is still a potential for some blood loss, usually from suturing the metal ring to the sclera. Any blood loss is typically less than a teaspoon, or less than two cc.

There is also a risk of infection. Since the cornea lacks blood vessels (it derives its nutrients from the aqueous humor), it heals much more slowly than a cut on the skin. While the wound is healing, it might become infected by various microorganisms. This risk is minimized by antibiotic prophylaxis (using antibiotic eyedrops, even when no infection exists).

How successful is a cornea transplant?

When the primary purpose of a cornea transplant is to improve visual acuity, the prognosis depends on whether the rest of the eye is healthy. If it is, then it should be possible to recover normal vision.

While your eyesight should gradually improve a few weeks after a corneal graft, complete visual recovery could take six months to a year. After your cornea transplant has fully healed, it’s possible to undergo LASIK eye surgery to improve your vision.

Do corneal transplants last for life?

Some corneas do last a lifetime, but some need to be replaced. This could be due to transplant rejection, which can occur even 20 years later. And depending on the age and health of the donor tissue, the transplanted cells may fail over time.

Also see partial-thickness corneal transplantation: DSEK and DMEK.

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