What is the Cornea?
The cornea is the transparent, outermost part of the eye that covers the iris (the colored part) and the pupil (the black center). Although appearing to be one clear membrane, the human cornea actually has five distinct layers. The cornea functions like a window, allowing the image you are looking at to be carried in the form of light waves to the interior of your eye.
The cornea protects the eye from environmental debris and filters some of the sun’s most damaging UV rays. Because the cornea is the outermost part of the eye, it is subject to considerable abuse from the outside world. Particles of dust and grit inevitably find their way into our eyes, irritating them, and stimulating the production of tears to wash foreign materials away.
In order to function properly and provide clear vision, the cornea must remain healthy and clear. When the cornea is damaged by injury, disease or hereditary conditions, it may become swollen or scarred. These scars may cause the cornea to scatter or distort light, resulting in reduced vision, sometimes to the point of blindness. The smoothness and shape of the cornea is also vitally important to its proper functioning. If either the surface smoothness or the clarity of the cornea is disturbed, vision becomes distorted.
Repairing a Damaged Cornea
If the cornea is damaged, partial (DSAEK) or full thickness cornea transplant surgery is available depending on the severity of damage. For those who wish to reduce their need for corrective eyewear by reshaping the cornea, refractive eye surgery (LASIK) can reduce or eliminate the need for glasses or contacts.
Full Thickness Cornea Transplant
Corneal transplant surgery, also called keratoplasty, involves removing the central area of the cornea and replacing it with a donor’s cornea. Cornea transplants are the most commonly performed tissue transplant in the world, with some 48,000 procedures performed in the U.S. every year. Cornea transplant can restore vision, reduce pain and improve the appearance of a damaged or diseased cornea. A cornea transplant can treat a number of conditions. These include: thinning of the cornea, cornea scarring (caused by infection or injury), clouding of the cornea, swelling of the cornea, corneal ulcers and complications caused by previous eye surgery.
The surgery is a same-day procedure that takes between one and two hours. Before surgery, the patient is given a light intravenous sedative and the eye is anesthetized. When the transplant is complete, the surgeon secures the donor cornea to the eye with stitches. Antibiotic eye drops are placed, the eye is patched, and the patient is taken to a recovery area while the effects of the anesthesia wear off. The patient typically goes home following this and sees the doctor the following day for the first post-operative appointment.
Your risk of complications and cornea rejection continues for years after your cornea transplant. For this reason, expect to see your eye doctor annually. Cornea rejection can often be managed with steroid medications.
Partial Thickness Cornea Transplant (DSAEK) Partial thickness cornea transplant, also called DSAEK (Descemet’s Stripping Automated Endothelial Keratoplasty) replaces just the back portion of the cornea. The cornea has five layers and the deepest layer is delicate and can be damaged in diseases such as Fuchs dystrophy. In DSEK, the thin endothelial layer is removed and replaced with a similar layer from a donor cornea. This is an excellent alternative to a full thickness transplant in certain patients that have a healthy cornea except the back layer. There is faster visual recovery, less astigmatism, and fewer stitches needed than a full thickness transplant. In addition this surgery can be combined with cataract surgery. Like any corneal transplant procedure there is still some risk of infection or rejection of the new donor tissue, so taking your medications properly and careful follow-up examinations are important.