CORNEAL DISEASES AND CORNEAL TRANSPLANT
WHAT IS THE CORNEA?
The cornea is the most anterior part of the eye; it is transparent in order to let light in, until hitting the retina, where the visual process will begin. Diseases that directly or indirectly affect the cornea and its transparency, will interfere in the passage of light, the end result will be loss of vision.
WHAT CAN DAMAGE THE CORNEA?
Knives, pencils and other sharp objects can cause serious injuries to the cornea. Fireworks, battery explosions and toxic chemicals, especially alkalis like lye, can also cause severe corneal scarring. In fact, accidents involving the cornea are the leading cause of emergency eye care. When the injury is due to a chemical, flush the eye with plenty of water or saline. Many corneal injuries are preventable with the use of specific goggles and taking precautions when handling hazardous substances.
WHAT ARE THE CAUSES OF DISEASE AND CORNEAL DEGENERATION?
Bacterial, fungal or viral infections are common causes of severe corneal ulceration and alterations. Changes in the dome-shaped of the cornea (keratoconus), degenerations that can occur after cataract surgery (corneal edema or swelling), and some degenerative processes may affect corneal transparency.
Some corneal diseases are hereditary, and can cause blurred vision and total loss of vision.
WHAT IS A CORNEAL TRANSPLANT?
When the cornea loses its transparency, the only way to restore vision is to replace the damaged cornea by a corneal transplant.
Corneal transplantation (keratoplasty) is the most successful of the tissue transplants. The average success depends on the cause of the loss of transparency of the cornea. For example, corneal transplants for degeneration secondary to cataract surgery, and those due to keratoconus, are those with the highest rate of success, while transplants secondary to chemical substances or immunological processes, have worse outcomes.
HOW IS A CORNEAL TRANSPLANT DONE?
The corneal tissue for transplant comes from an eye bank. The process begins with the application for a corneal transplant. The eye bank will register the request and if there is a donation by a deceased donor, the ophthalmologist will schedule the surgery. The operation involves replacing and implanting the central and transparent cornea of the donor to the patient's eye.
At present, it is possible to select the portion of the donor's cornea to be transplanted. That means that the entire cornea is not always needed (penetrating transplant), sometimes only a small part is needed. Then, if we have a patient whose cornea was damaged on the anterior layers because of a viral process, we will just replace, transplant these damaged layers, respecting the rest of the cornea, this is what we call lamellar transplant. Similarly, corneal diseases affecting only the corneal endothelium (the innermost layer of the cornea) can be cured by a selective transplant of this layer. This is called the endothelial transplant.
WHAT HAPPENS AFTER SURGERY?
Recovering the lost vision after a corneal transplant may take a while. Generally 20% to 30% of vision is recovered within the first days and the rest depends largely on the disease causing the corneal opacification and may take up to a year after surgery. As it happens by most of transplants, the patient can also reject the donor tissue. The major signs of rejection are redness of the eye and worsening of vision. If this happens, even after several years, the patient has to go quickly to the ophthalmologist.
WHY IS IT IMPORTANT TO HAVE YOUR EYES REGULARLY SCREENED BY AN OPHTHALMOLOGIST?
Eye diseases can occur at any age. Some do not cause symptoms until irreversible ocular damage starts. Blindness can be prevented with early diagnosis and treatment, thus regular medical examination by an ophthalmologist is very important. Why an ophthalmologist?, Because only an eye expert can provide the necessary care for your eyes in all regards: optical medical and/or surgical treatments.