Cornea transplant surgery involves removing a damaged or diseased cornea, and replacing it with tissue from a deceased donor. All or part of the cornea may be replaced. In the United States, eye surgeons do approximately 33,000 corneal transplants (keratoplasty) per year. The surgery might be recommended if vision is seriously impaired by scarring from an injury, or eye diseases such as Fuchs’ Dystrophy, Lattice Dystrophy, or Keratoconus.
What is the Cornea’s Job?
The cornea is transparent tissue at the front of the eye. Its job is to protect the eye from damage. This tissue also absorbs oxygen and nutrients. Light enters through the cornea first, then the pupil, then the lens of the eyes to the retina.
There are five layers of the cornea. A penetrating (full thickness) transplant replaces the entire cornea. Lamellar corneal transplants replace only some of the layers. A Lamellar transplant is less invasive, but can only be used when the problem limited to a part of the cornea. Typical procedures include Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK), Descemet’s Membrane Endothelial Keratoplasty (DMEK), and Anterior Lamellar Cornea Transplant (layers closer to the organ’s surface).
What Can Damage the Cornea?
The cornea has unique self-healing qualities. Corneal scratches from assaults such as fingernails, branches, and eye makeup applicators are common, and they can be quite painful. Consult an eye doctor, who may prescribe antibiotic drops and special contact lenses to help with healing. In this very delicate part of the body, the cells slide into scratches and fill them. Sometimes, scarring occurs that impairs vision and may ultimately require a transplant.
Eye infections can be severe enough to cause corneal scarring. Chemical injuries can also cause scars. On rare occasions, complications from cataracts surgery and other treatments can later require a corneal transplant.1
Keratoconus is a bulging of the cornea that affects approximately 0.1% of the population. The cornea changes from the natural shape into a cone. Tears in the Dua layer, which let fluid build up, or deterioration of the Bowman’s Layer causing thinning may lead to bulging. Chronic severe dry eye conditions can also result in corneal scarring if not treated.
Several genetic diseases damage the cornea. In Fuchs’ Dystrophy, the corneal endothelium layer stops removing fluid correctly, causing clouding and tiny, painful blisters. Patients with lattice dystrophy can sometimes benefit from a corneal transplant, as can those with map-dot-fingerprint dystrophy.
What is Cornea Transplant Surgery?
Many corneas are available locally, so the waiting period can be just days. No matching is needed — virtually any healthy cornea will work. Corneas are highly unlikely to be rejected by the body. Systemic anti-rejection drugs are not needed.
Most of the time, the cornea transplant is performed in a couple of hours using local anesthetic and a mild sedative. It can be done under general anesthetic if necessary.
Local anesthetic is injected into the skin near the eyes to relax blinking and eye movement muscles. Eye drops numb the eye. Most patients report no discomfort during the entire procedure. A lid speculum holds the eyes open while they are numb.
If the entire cornea is being replaced (penetrating keratoplasty (PK), a special tool or laser removes the damaged cornea. An identically-shaped cornea from the donor is painlessly sutured in its place using tiny stitches. To protect it, a plastic shield is placed over the eye. The stitches may need to stay in place for a year or more, and might require adjustments.
If the patient is eligible for partial replacement (Lamellar, endothelial keratoplasty or EK), the surgeon cuts into the side of the cornea, removes the damaged layer and replaces it with a corresponding layer of healthy donor tissue. A tiny air bubble may be used to hold the new tissue in the right place. This surgery does not usually require stitches.
There are many ways that replacing one layer is better than replacing the entire cornea:
- better vision outcomes and stability
- less risk
- no stitches, and no complications from stitches
- faster vision recovery
- shorter operating time
- less removal of corneal tissue, which helps to maintain the structural integrity of eye and reduces the chance of injury
- reduced post-operative astigmatism
What Happens After the Cornea Transplant Surgery?
Recovery time varies, and the cornea heals relatively slowly. If an air bubble was used in surgery, the patient may be asked to lay flat for several days. A plastic shield often protects the eye during the first days after surgery. Patients will be prescribed a regimen of eye drops, including steroidal drops that reduce the chance of rejection. These drops may be continued for several months or longer as per the doctor’s instructions.
Vision may initially get worse after surgery, but it will gradually improve over a few months. Stitches, if used, might stay in for months or years. The doctor can adjust or remove them during in-office visits. Adjustments can improve astigmatism caused by the surgery.
Complications may include scarring, cataracts, retinal detachment, or damage to other parts of the eye, and fluid leakage from the incision. Rarely, there is bleeding or infection.
A new corrective prescription will be needed after the cornea is healed. The cornea trnasplant surgery changes the surface of the eye, causing astigmatism, nearsightedness, or farsightedness to a greater or lesser degree. This is especially pronounced for patients who get the entire cornea replaced. Laser surgery can be used to correct refractive errors in some patients. Glasses and/or contact lenses are needed to correct vision.
Keeping follow-up appointments with the eye doctor is crucial to a successful recovery.
In the years following the surgery, take care to protect the transplanted corneal tissue. Wear protective goggles during sports and when making household repairs. Glasses help protect the eye. Wear sunglasses in sunlight to protect the entire eye from UV damage.
How Effective is This Surgery?
Total corneal replacements have been in use longer, so more statistics about their long-term outcome are available. In Fuchs’ Dystrophy patients, a full cornea transplant lasts at least a decade in 73% of patients2 For keratoconus patients, 89%. And for corneal scarring, 60-70%. If herpese simplex is present Infection may reoccur in the cornea.
Partial replacements generally have better long-term results.
Rejection happens in less than 20% of patients overall, and the chances of rejection are lower with partial corneal replacements. Rejection symptoms should be reported to the eye surgeon immediately. These symptoms include redness, extreme light sensitivity, decreased vision, and/or pain. Quick treatment with drops can reverse most cases of rejection.
Advances in corneal replacement surgery mean people with damaged or diseased corneas have a good chance of improving their vision. Fuchs’ Dystrophy patients no longer face pain and blindness, and victims of corneal scarring can see clearly again.