When is a cornea transplant necessary?
There are many conditions that can affect the complete transparency of the cornea. For example, a trauma or injury to the cornea that can leave scars, as well as infections (especially herpes keratitis). A hereditary condition called Fuchs' dystrophy causes corneal failure. Keratoconus (see example in photo) causes the cornea to protrude forward, forming a pronounced curve. Occasionally, there may be a corneal failure after eye surgery, such as cataract surgery.
A corneal transplant is necessary if vision cannot be satisfactorily corrected with glasses or contact lenses, or if a painful swelling cannot be relieved with medication or special contact lenses.
Corneal transplant options
A cornea transplant is performed using a donor cornea. Before the cornea is removed for transplantation, tests for viruses that cause hepatitis, AIDS, and other potentially infectious diseases must be performed. The transparency of the donor's cornea is also examined.
During a traditional corneal transplant surgery (known as penetrating keratoplasty), a circular portion of the diseased cornea is removed. An equally sized circular area is cut in the center of the donor cornea, which is then placed and sutured onto the patient.
In a corneal transplant called endothelial keratoplasty, only the abnormal inner lining of the cornea is removed. A thin disc of tissue from a donor containing a healthy layer of endothelial cells is placed on the back surface of the cornea. A bubble of air is used to push the layer of endothelial cells into place until it heals in the proper position.