Corneal Transplantation
If eyes are considered the window into the soul, then the cornea is literally the window into the eye. The cornea is the clear, transparent tissue that vaults over your pupil and iris. Its main function is to refract or bend light into focus for the purpose of seeing. When this tissue loses its clarity or becomes biomechanically unstable, a corneal transplant may be indicated. The purpose of a corneal transplant is to improve overall vision, but sometimes it is also performed to relieve the eye of pain. Examples of conditions that may require a corneal transplant include corneal ulcers, corneal scarring, corneal dystrophies, corneal edema and ectatic conditions such as keratoconus.
A corneal transplant is the replacement of the individual or patient’s corneal tissue with tissue from a healthy donor. Corneal disease is the fourth common cause of blindness. Over 65,000 transplants are performed in the United States every year. There are two main kinds of corneal transplants: A full thickness penetrating keratoplasty and a partial thickness endothelial keratoplasty. The goal of both of these procedures is to replace damaged corneal tissue with healthy tissue, restoring corneal clarity and transparency required for optimal vision.
Your doctor will undertake a complete examination of the eye in order to determine whether you are an appropriate candidate for a corneal transplant. This includes:
- Visual acuity and refraction: Testing your vision in each eye
- Slit lamp examination: A thorough evaluation of the anterior structures of the eye including the cornea
- Dilated fundus exam: A thorough evaluation of the posterior structures of the eye including the retina and the optic nerve
Based on the findings of your eye exam, your ophthalmologist will recommend the correct course of action. This may include non-surgical options such as optimizing the vision with glasses or contact lenses or proceeding with surgery.
What Is a Penetrating Keratoplasty?
A penetrating keratoplasty is typically required when there is scarring or damage to the anterior or all layers of the cornea. In this approach, a full thickness circular disc of corneal tissue is removed centrally and replaced by healthy donor tissue, which is secured by stitches. This procedure is performed on an outpatient basis and typically takes one to two (1-2) hours to perform.
On the day of surgery, you will receive a relaxing sedative along with a local anesthetic injection around the eye for comfort. Following the surgery your eye will have a patch and shield over it, which your doctor will remove the following day. It is normal for vision to be extremely blurry initially. The recovery time varies from months up to a year. Glasses or contact lenses may be required to further optimize vision.
What Is an Endothelial Keratoplasty?
Endothelial keratoplasty selectively replaces only the innermost cells of the cornea called the endothelial cells. The endothelial cells are responsible for pumping fluid out of the cornea, allowing it to maintain its clarity and compactness. If these cells fail, the cornea swells, causing a decrease in vision. Conditions that selectively affect the endothelium, such as Fuchs' dystrophy, benefit from this specific procedure.
On the day of surgery, you will receive a relaxing sedative along with a local anesthetic injection around the eye. Following surgery, your eye will have a patch and shield over it, which the doctor will remove the next day. It is imperative that for the immediate 24 hours following surgery, you keep your head reclined at all times so that you are facing the ceiling. This positioning ensures that the air bubble is keeping the graft in place to allow it to attach. Expect your vision to be blurry following the surgery given the presence of an air bubble and time needed for the cornea to properly heal.
The advantages of endothelial keratoplasty include a quick recovery time, minimal removal of corneal tissue and low induced astigmatism. As with any procedure, there are always risks. The risks of corneal transplantation (whether full thickness or partial thickness) include rejection of the graft and infection, among others.
