What is a Corneal transplant?

Introduction
History
The Donor TissueThe Donor
Indications for Surgery
Preparing for Surgery
The Operation
After Surgery
Risks and Complications
Frequent Questions

Introduction
The cornea is the clear dome-shaped "window" in the front of the eye. Behind this clear window lies the iris, or colored portion of the eye. The cornea serves two purposes:
1: It forms the front part of the eye's outer wall or shell and focus images on the retina at the back of the eye.
2: With its curved shape, the cornea acts like a camera lens to transmit light and focus images on the retina at the back of the eye.

Following disease or injury, the cornea may become weakened, cloudy, or irregular in shape. If medicines are ineffective, in some cases the damaged cornea can be replaced with a healthy cornea from a deceased person. This replacement procedure is called "corneal Transplant" or "penetrating keratoplasty."

This home page describes corneal transplant surgery. The information is designed to accompany but not replace the discussions before and after surgery. If you have further questions, please ask your doctor. It is important that you take as much time as you need to understand your condition and possible treatments.

History
Although attempts at corneal transplantation were made 100 years ago, the first consistent success was achieved by Dr. Castroviejo and Dr. fine in the 1950s. Corneal transplant is the most successful of all tissue transplants. An estimated 40,000 such operations are performed in the United States each year.

The Donor Tissue
Corneal tissue for tarnsplatation comes from an eyebank. The process begins at the death of someone who has been generous enough to donate his or her eyes. The eyebank carefully screens the donor tissue to rule out any disease that might be transmitted to the recipient. The tissue becomes available, the local eyebank enters the information into a nationwide computer network. The corneal tissue is then flown free of charge to the site where it is needed. Eyebanks charge a fee only for processing the corneal tissue.

It is the policy of all eyebanks that the donor remain anonymous. There is no incompatibility of donor and recipient tissue on the basis of sex or race, or need for glasses. the color of the donor eye is also irrelevant, since only the transparent dome in the front of the eye is replaced, and not the colored iris behind it.

Indications for Surgery
Corneal Transplants are done to improve vision, relieve pain , and protect the inner structures of the eye.

The transplant repairs damage from injuries infections. Knives, pencils, other sharp objects, fireworks, and chemicals can cause severe injury to the cornea. Bacterial, viral, and fungal infections are frequent causes of sever corneal scarring and ulceration. Abnormal steepening of the cornea (keratoconus), occasional degeneration after cataract surgery, and some aging processes can also damage the cornea. Inherited corneal abnormalities (dystrophies) can lead to corneal clouding and loss of sight.

Preparing for Surgery
A general medical examination and routine laboratory tests such as blood count and EKG help insure that you are well enough to undergo surgery. Aspirin is not used for 2 weeks prior to surgery, since it tends to cause bleeding during surgery. Antibiotic drops to protect the eye from infection are generally started one day before surgery. It is important to not eat or drink anything (except a sip of water for medicines) after midnight the day before surgery.

In most cases, the surgery can be done on an outpatient bases. At the surgery center, medication is given to relax the patient before surgery. A small weight is placed on the closed eye to soften the eye. An IV line and EKG monitoring are standard safety precautions.

Local or general anesthesia can be used, based on age, general health, length of surgery, and patient preference. Local anesthesia consists of two small injections, one behind the ear and one in the lower eyelid. Sufficient sedation is given so that the local anesthetic is hardly felt.

The eyelids are carefully washed and covered with a sterile plastic drape. Fresh oxygen is provided by a plastic tube palced near the nose. Patients often doze off during the operation, and most are left with vague recollections of a short procedure.

The Operation
The entire procedure si done under a microscope. A circular knife called a trephine is used like a cookie cutter to remove the center of the diseased cornea. a "button" of similar size is cut from a donor cornea. This donor tissue is then sewn in place with extremely fine nylon sutures.

If it has been determined before surgery that a cataract (cloudy lens) is present, the cataract may be removed and replaced with a clear plastic lens during the corneal transplant operation.

If the eye has previously had cataract surgery, but the plastic lens implant is damaging the cornea, the faulty lens implant can be replaced with a new one at the time of corneal transplant surgery.

At the conclusion of the procedure, a patch and metal shield are applied to protect the eye.

After Surgery
Pain caries from person to person. Typically there is either no pain or only slight soreness for a few days, relieved by Tylenol.

The operated eye is patched until the surface epithelium is healed, usually 1 to 4 days. After the patch is removed, it is important to wear something hard in front of the eye (glasses or a metal shield) at all times to give it protection. Typically, patients wear their glasses during the day. A metal shield is worn at night for several months.

After surgery, the rest of the day should be spent in bed. Sleeping on the operated side is acceptable. After the first day, shaving, brushing teeth, bathing, light housework, bending over, walking, reading, and watching TV will not hurt the eye. Showering, shampooing, sexual astivity, and vigorous exercise can be resumed after one week.

Since the new cornea is delicately sutured in place, a direct poke to the eye must be avoided. Contact sports are discouraged after corneal transplant. Otherwise, normal activity can be resumed within a few days.

Because the cornea has no blood supply, the transplant heals relatively slowly. Sutures are left in place for three months to one year, and in some cases they are left in permanently. The sutures are buried and therefore do not cause discomfort. To reduce astigmatism (irregular shape of the cornea), suture tension may be adjusted as early as three weeks after surgery. Suture adjustment and removal are simple, painless office procedures.

Vision gradually improves as the new cornea heals. There is often useful vision within a few weeks. However, in some cases it may take several months to a year for full vision to develop.

To prevent rejection of the new cornea, steroid drops are placed in the eye for several months after surgery. In some cases, low dosage steroid drops are continued in definitely. Unlike oral steroides, steroid eye drops cause no side effects elsewhere in the body. Occasionally other eye medications are necessary.

It is important to call immediately (including weekiends, evenings, and holidays) for any unusual symptoms, including Redness, Sensitivity to lights, Vision loss, or Pain ("RSVP"). Flashing lights, floaters, and loss of peripheral vision should also be reported immediately.

Postoperative care is extremely important and by far the most time-consuming part of having a corneal transplant. The eye is checked the day after surgery, several times in the first two weeks, at gradually longer intervals over the first year, and usually yearly thereafter.

Risks and Complications

No surgical procedure is completely free of risk. Possible complications include but are not limited to astigmatism, infection, bleeding, retinal detachment, glaucoma, and cataract. Occasionally, the donor cornea is rejected (becomes cloudy). Following such complications, vision may end up the same or worse after surgery.

Problems unrelated to the corneal transplant surgery, such as retinal scarring (macular degeneration) or optic nerve damage from increased eye pressure (glaucoma) may lead to poor vision even if the corneal transplant operation is successful.

On very rare occasions, diseases have been transmitted to a recipient patient through a donor cornea. As with any kind of surgery, there is a remote possibility of death or brain damage due tu adverse reactions to anesthesia or medications. Patients undergoing this operation shoud do so with a mature consideration of these facts.

Frequent Questions

• Q: How long will I have ot wait for my corneal transplant?
• A: In most cases, surgery is scheduled within a few weeks. In emergencies(for example, a corneal performation), surgery can be done within a day.

• Q: Can artificial palstic corneas be used for tranplants?
• A: No. Plastic implants are used only to replace a cloudy lens (cataract) inside the eye. For corneal transplants, living tissue must be used.

• Q: Will my eye be the same color after a corneal transplant?
• A: Yes. Onyly the transparent dome in the front of the eye is replaced, and not the colored iris behind it. In some cases, existing corneal scars block the true color of the eye, and therefore the tye appears to have changed color after the operation.

• Q: What is a rejection?
• A: If the body's immune system recognizes the new cornea as foreign tissues, cells start to attack the endothelium of the donor cornea, the innermost cell layer that nomally pumps water out of the cornea to keep it clear. Therefore, the new cornea becomes swollen and cloudy.

• Q: Does the new cornea fall out if it is rejected?
• A: No. It simply becomes cloudy, blurring the vision.

• Q: When do rejections occur?
• A: Most occur in the fist year, but they can happen later as well.

• Q: What are the warning signs of rejection?
• A: Redness, Sensitivity to light, decreased Vision, or Pain ("RSVP"). These shoud be reported immediately.

• Q: Is there any treatment for rejection?
• A: Yes. When detected early, rejection can e reversed 90% of the thime by intensive use of topical steroids and other medications. It is important to immediately report any warning signs, since graft survival depends heavily on early detection and treatment of rejection episodes.