What Is a Cornea Transplant?
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.
Dayton Eye Associates cornea specialist, Dr. Denlinger, is a fellowship trained cornea specialist with extensive experience in performing cornea transplants.
What Conditions Does a Corneal Transplant Fix?
A number of conditions can be treated with a cornea transplant, including:
- A cornea that bulges outward (keratoconus)
- 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
Are There Risks With Cornea Surgery?
Cornea transplant is a relatively safe procedure. Still, a cornea transplant does carry a small risk of serious complications, such as:
- Eye infection
- Increased risk of clouding of the eye’s lens (cataracts)
- Pressure increase within the eyeball (glaucoma)
- Problems with the stitches used to secure the donor cornea
- Rejection of the donor cornea (a lifelong risk)
- Swelling of the cornea
Once you have a cornea transplant done it is extremely important to keep your follow-up appointments with your surgeon. Many complications can be treated successfully with early recognition.
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 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
Types of Cornea Transplants
Full Thickness Penetrating Keratoplasty (PKP)
This is considered the “traditional” type of transplant and this technique has been around for decades. During penetrating keratoplasty, your surgeon cuts through the entire thickness of the abnormal or diseased cornea to remove a small button-sized disc 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 tiny stitches to suture the donor cornea into place. The sutures are left in my place for several months to years depending on the patient. Although penetrating keratoplasty isn’t performed as often these days because of new transplant techniques, it is still the best option for many patients.
Descemetls Stripping Endothelial Keratoplasty (DSEK)
This is a more recently developed procedure that involves only replacing the innermost layers of the cornea rather than the whole cornea as in penetrating keratoplasty. In conditions such as Fuchs endothelial dystrophy, the innermost layer called the endothelium is diseased. This results in swelling of the cornea causing decreased vision. Previously to replace the valuable endothelial layer the whole central cornea was replaced by performing a Penetrating Keratoplasty. With innovative techniques, we are now able to replace just the innermost layer.
The procedure involves peeling off the inner two layers of the diseased cornea. A donor cornea is then split or dissected to create a flap of the inner two layers and a small portion of stroma (to provide substance for manipulation). This 3 layer donor is then folded and inserted into the eye. It is then unfolded and lifted up against the patient’s cornea using an air bubble. The air bubble is then left in the eye to hold the donor cornea in position. The air bubble dissolves over a few days and the donor cornea naturally adheres to the patient’s cornea. Sometimes the graft does detach from the host cornea in the early post-operative period and has to be repositioned with a new air bubble.
DSEK has proven to have many advantages over traditional penetrating keratoplasty. These include a more rapid visual recovery (weeks to months as opposed to months or years), less astigmatism, early suture removal, and appear to have less overall complications.
Deep Anterior Lamellar Keratoplasty (DALK)
Deep Anterior Lamellar Keratoplasty (DALK) is a newer method of cornea transplant for anterior corneal disease such as keratoconus, corneal scars and stromal dystrophies. The procedure is similar to penetrating keratoplasty (PKP) but only the anterior layers of the cornea are replaced and the inner most layer of the recipient, the endothelium, is retained. Because the inner layer is retained, the body does not recognize the donor tissue, hence there is less risk of rejection.
The procedure is technically challenging as the endothelial layer is extremely thin and can be easily torn during surgery. If this complication occurs the procedure is converted to a traditional penetrating keratoplasty. In DALK many small sutures are used to hold the transplant in place, just like in traditional penetrating keratoplasty.
A pterygium is a triangular-shaped tissue growth, yellow-white to pinkish in color, usually on the nasal side of the cornea. It may become red, inflamed or advance toward the center of the eye. Some pterygia grow slowly throughout a person’s life, while others stop growing after a certain point. A pterygium can cause a decrease in vision once it grows onto the cornea. A pterygium can also cause chronic irritation and redness.
If a pterygium begins to cause a decrease in vision or constant irritation it may require surgery to remove it. The surgery is usually done as an outpatient with local anesthesia. During the procedure the surgeon will remove the pterygium from the cornea and conjunctiva. Rather than leave a bare defect behind, most surgeons will harvest a patch of conjunctival tissue (conjunctival autograft) from the patient’s own eye and place it into the defect. The autograft is then sutured or glued into place. An autograft dramatically reduces the risk a pterygium will grow back.
Superficial Keratectomy / Epithelial Debridement & Polish
Certain conditions that affect the outer layer of the cornea (recurrent erosion syndrome, map-dot-fingerprint dystrophy, basement membrane dystrophy, Salzmann’s nodules, band keratopathy) may require removal of the epithelium to treat the condition. During this procedure, which can usually be done in the office using just numbing drops, the outer layer of the cornea (the epithelium) is gently removed using a blunt spatula. A diamond burr may then be used to polish the cornea surface. If band keratopathy (calcium deposits) is present, a solution called EDTA may be applied to the cornea surface to dissolve the calcium. A bandage contact lens is then placed in the eye at the conclusion of the procedure. The contact lens aids in comfort and speeds up the healing time.
Finding a Donor Cornea
Rejection occurs in about 20 percent of cornea transplants. Put another way, for every 10 people receiving cornea transplants, two people can expect to experience rejection of the donor cornea. It is not uncommon to keep patients on steroid drops for the rest of their life to lower the risk of rejection. Most corneas used in cornea transplants come from deceased donors. Unlike with other organs, such as livers and kidneys, people needing cornea transplants generally don’t have to endure long waits. That’s because nearly all people can donate their corneas after they die, so more corneas are available for transplant compared with other organs. In addition, unlike other organ transplants, strong immunosuppressive drugs are usually not required to prevent rejection of a cornea transplant. Most often only steroid eye drops are needed to prevent rejection.