About Corneal Transplantation
A Corneal Transplant is a surgical procedure to remove all or part of the diseased or injured cornea and replace it with a similarly sized and shaped part of a healthy donor cornea.
TYPES of TRANSPLANTS:
Penetrating or full thickness transplants involve removing the entire diseased or injured cornea from the recipient and replacing it with a healthy donor cornea. In this procedure, sutures are sewn onto the graft to ensure proper placement of the tissue. Usually, a rigid hard contact lens is placed over the graft to simulate better visual potential during the first months post-transplant.
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Anterior Lamellar Keratoplasty transplants replace only a section of the diseased or injured cornea instead of the entire cornea such as when a Deep Anterior Lamellar Keratoplasty (DALK) surgery is performed. In this type of procedure, only the front part of the recipient cornea needs to be replaced and not the entire cornea. Because only a section of recipient corneal tissue is removed, the risk of rejection is less likely and the eye is less vulnerable to injury and infection.
Endothelial Lamellar Keratoplasty occurs when the recipient’s outer cornea is rather healthy; however, the most posterior layer (corneal endothelium) is diseased or injured. In this procedure, only the recipient’s endothelial layer (the back 10%) portion of the cornea is removed and replaced with the back 10% of the healthy donor cornea. The remaining 90% of the recipient cornea remains intact. This procedure is termed Deep Endothelial Lamellar Keratoplasty (DELK). This procedure requires no sutures to keep it in place, allowing the recipient’s graft to heal much quicker, less chance of infection or rejection occurs and less induced astigmatism occurs.
Corneal transplantations are performed for several reasons, including the following:
- Optical: To improve the optical qualities of the cornea to improve vision by replacing a scarred cornea with a healthy, clear one.
- Reconstructive: To reconstruct a perforated cornea to preserve the eye in its whole form.
- Therapeutic: To treat a disease unresponsive to medical management such as uncontrolled fungal corneal ulcers or to alleviate the pain of a severe foreign-body sensation due to recurrent ruptured blister-like lesions in Bullous Keratopathy.
COMMON INDICATORS for TRANSPLANTATION
Bullous Keratopathy, Fuchs’ Endothelial Dystrophy, Keratoconus, Repeat Graft, Keratitis, Viral or Bacterial Problems, Fungal Ulcers, Perforations, and Corneal Stromal Dystrophies are the most common indications for a corneal transplant.
Corneal transplants can be performed using general or local anesthetic plus intravenous sedation. To prepare the tissue for the most common of transplants, Penetrating Keratoplasty, the surgeon removes a corneal button from the central part of the donor cornea using an instrument called a trephine. To create the recipient bed to receive the donor corneal button, the surgeon removes the central 60 to 80% of the host cornea using similar instruments. The donor corneal button, which is trephined slightly larger than the recipient bed, is then sutured in place.
Postoperative medications are used for several weeks and topical steroids for several months. In some cases, corneal astigmatism occurs and can be reduced by suture adjustment or the removal of selected sutures. Full visual potential may take quite some time because of the healing process, corneal astigmatism and other factors.
In many patients, a rigid contact lens is placed over the corneal transplant to simulate the smooth, glossy surface of a healthy cornea.
To protect the eye from inadvertent trauma after transplantation, the recipient may wear a patch with a plastic or metal shield, and/or protective eye glasses or sunglasses. Recipients are usually advised against bending over to pick up a heavy object or straining.
The corneal transplant is not only the oldest transplant performed, but also the most common and successful human transplant performed. The prognosis for a clear, functioning corneal transplant varies by diagnosis. The chance of long-term transplant success is higher than 94%, according to the Eye Bank Association of America. The generally high rate of success of corneal transplantation is attributed to many factors, including the effectiveness of the immunosuppressive drugs used to treat graft rejection.
If you have any concerns, contact your Ophthalmologist. Your doctor will be able to inform you of the risks and rewards of the corneal transplant.