Cornea

Cornea

When is corneal transplant surgery necessary?

The cornea is a clear dome of tissue that covers the front central portion of the eye. It functions primarily as the window to the eye. It allows light to enter the eye and bends (refracts) the light rays to help the lens focus them upon the retina. The normal cornea is completely transparent living tissue. To perform properly, the cornea must be crystal clear and be of a proper curvature.

Due to injury or disease, the cornea may become damaged and opaque or may develop uncorrectable abnormalities of its curvature. If the cornea is not perfectly clear, light may no longer effectively pass through it, resulting in diminished vision. If the cornea is irregular or damaged, or irregularly curved, it will cause blurred vision. Replacing cloudy, damaged, or distorted corneal tissue with healthy donor tissue via corneal transplantation can result in dramatic improvement in vision.

There are many causes of scarring and clouding of the cornea including the following:

  • Eye injuries can cause scarring of the cornea. These injuries may include penetrating or blunt corneal trauma, thermal or chemical burns.
  • Severe corneal infections may lead to corneal scarring. These infections may be bacterial, viral, fungal, or parasitic in origin. Herpes viruses are probably the most common cause of such scarring.
  • Abnormal thinning diseases of the cornea, such as keratoconus, may result in scarring of the central cornea and distort vision so severely that glasses or contact lenses are of little help.
  • Inherited corneal dystrophies may cause clouding clouding.
  • Some inherited systemic diseases may also cause visually significant clouding of the cornea.
  • Complicated cataract (or other eye) surgeries can cause corneal decompensation with  resultant swelling, and clouding.

How is corneal transplant surgery performed?

There are a variety of partial and full thickness corneal transplant procedures available to address the multiple causes of corneal opacification. Usually, the surgeon removes a portion or all of the central cloudy cornea and replaces it with clear donor corneal tissue. Sometimes if multiple layers of the cornea are involved in the patient’s disease process, the full thickness central cornea needs to be replaced, as in classic penetrating keratoplasty or PKP. Under other circumstances, only portions or layers of the cornea need to be replaced utilizing lamellar keratoplasty techniques such as the more recently developed DSEKand DMEK (now the preferred procedures for most patients with a disease called Fuchs’ Corneal Dystrophy) and DALK procedures.

Dr. Marc A. Goldberg is The Eye Institute’s Cornea Specialist.

To learn more about Corneal Transplants, click here.