A cornea transplant (keratoplasty) is a surgical procedure to replace part of your cornea with corneal tissue from a donor. Your cornea is the transparent, dome-shaped surface of your eye that accounts for a large part of your eye's focusing power.
A cornea transplant can restore vision, reduce pain and improve the appearance of a damaged or diseased cornea.
Most cornea transplant procedures are successful. But cornea transplant carries a small risk of complications, such as rejection of the donor cornea.
Why it's done
A cornea transplant is most often used to restore vision to a person who has a damaged cornea. A cornea transplant may also relieve pain or other signs and symptoms associated with diseases of the cornea.
A number of conditions can be treated with a cornea transplant, including:
- A cornea that bulges outward (keratoconus)
- Fuchs' dystrophy
- Thinning of the cornea
- Cornea scarring, caused by infection or injury
- Clouding of the cornea
- Swelling of the cornea
- Corneal ulcers, including those caused by infection
- Complications caused by previous eye surgery
Cornea transplant is a relatively safe procedure. Still, it does carry a small risk of serious complications, such as:
- Eye infection
- Increased risk of clouding of the eye's lens (cataract)
- Pressure increase within the eyeball (glaucoma)
- Problems with the stitches used to secure the donor cornea
- Rejection of the donor cornea
- Swelling of the cornea
Signs and symptoms of cornea rejection
In some cases, your body's immune system may mistakenly attack the donor cornea. This is called rejection, and it may require medical treatment or another cornea transplant.
Make an appointment with your eye doctor if you notice any signs and symptoms of rejection, such as:
- Loss of vision
- Sensitivity to light
Rejection occurs in about 10 percent of cornea transplants.
How you prepare
Before cornea transplant surgery, you will undergo:
- A thorough eye exam. Your eye doctor looks for conditions that may cause complications after surgery.
- Measurements of your eye. Your eye doctor determines what size donor cornea you need.
- A review of all medications and supplements you're taking. You may need to stop taking certain medications or supplements before or after your cornea transplant.
- Treatment for other eye problems. Unrelated eye problems, such as infection or inflammation, may reduce your chances of a successful cornea transplant. Your eye doctor will work to treat those problems before your surgery.
Your doctor will discuss what to expect during the procedure and explain the risks of the procedure.
Finding a donor cornea
Most corneas used in cornea transplants come from deceased donors. Unlike with organs such as livers and kidneys, people needing cornea transplants generally will not need to endure long waits. That's because many people specifically request that their corneas be available for donation after they die, unless they have had certain conditions, so more corneas are available for transplantation.
Corneas may not be used from donors who had several conditions, such as certain central nervous system conditions, infections, and prior eye surgery or eye conditions, or from people who died from an unknown cause.
What you can expect
During the procedure
On the day of your cornea transplant, you'll be given a sedative to help you relax and a local anesthetic to numb your eye. You won't be asleep during the surgery, but you shouldn't feel any pain.
During the most common type of cornea transplant (penetrating keratoplasty), your surgeon cuts through the entire thickness of the abnormal or diseased cornea to remove a small button-sized disk of corneal tissue. An instrument that acts like a cookie cutter (trephine) is used to make this precise circular cut.
The donor cornea, cut to fit, is placed in the opening. Your surgeon then uses a fine thread to stitch the new cornea into place. The stitches may be removed at a later visit when you see your eye doctor.
In some cases, if people aren't eligible for a cornea transplant from a donor cornea, doctors may insert an artificial cornea (keratoprosthesis).
Procedures to transplant a portion of the cornea
With some types of cornea problems, a full-thickness cornea transplant isn't always the most appropriate treatment. Other types of transplants may be used that remove only certain layers of cornea tissue, or only tissue affected by disease. These types of procedures include:
Endothelial keratoplasty (EK). This procedure removes diseased tissue from the back corneal layers, including the endothelium, along with the Descemet membrane, a thin layer of tissue that protects the endothelium from injury and infection. Donor tissue is carefully implanted to replace the removed tissue.
There are two types of endothelial keratoplasty. The most common type, called Descemet stripping endothelial keratoplasty (DSEK), uses donor tissue to replace about one-third of the cornea. A newer type of procedure, called Descemet membrane endothelial keratoplasty (DMEK), uses a much thinner layer of donor tissue. Because the tissue used in DMEK is extremely thin and fragile, this procedure is more challenging than DSEK, and not as commonly used.
Anterior lamellar keratoplasty (ALK). This procedure removes diseased tissue from the front corneal layers, including the epithelium and the stroma, but leaves the back endothelial layer in place.
The depth of cornea damage determines the type of ALK procedure that's right for you. Superficial anterior lamellar keratoplasty (SALK) replaces only the front layers of your cornea, leaving the healthy endothelium intact. A deep anterior lamellar transplant (DALK) procedure is used when cornea damage extends deeper into the stroma.
In DALK, a small incision is made in the side of your eyeball to allow for removal of your cornea's front and middle layers without damaging the back layers. Healthy tissue from a donor is then attached (grafted) to replace the removed portion.
After the procedure
Once your cornea transplant is completed, you can expect to:
- Receive several medications. Eyedrops and, sometimes, oral medications immediately after cornea transplant and during recovery will help control infection, swelling and pain.
- Wear an eye patch. An eye patch may protect your eye as it heals after your surgery.
- Protect your eye from injury. Plan to take it easy after your cornea transplant, and slowly work your way up to your normal activities, including exercise. For the rest of your life, you'll need to take extra precautions to avoid harming your eye.
- Return for frequent follow-up exams. Expect frequent eye exams in which your doctor looks for complications in the first year after surgery.
Most people who receive a cornea transplant will have their vision at least partially restored. What you can expect after your cornea transplant depends on the reason for your surgery and your health.
Your risk of complications and cornea rejection continues for years after your cornea transplant. For this reason, expect to see your eye doctor annually. Cornea rejection can often be managed with medications.
Vision correction after surgery
Your vision may initially be worse than before your surgery as your eye adjusts to the new cornea. It may take several months for your vision to improve.
Once the outer layer of your cornea has healed — several weeks to several months after surgery — your eye doctor will work to make adjustments that can improve your vision, such as:
- Correcting unevenness in your cornea (astigmatism). The stitches that hold the donor cornea in place on your eye may cause dips and bumps in your cornea, making your vision blurry in spots. Your doctor may correct some of this by releasing some stitches and tightening others.
- Correcting vision problems. Refractive errors, such as nearsightedness and farsightedness, can be corrected with glasses, contact lenses or, in some cases, laser eye surgery.