OHSU

Casey Eye Institute at OHSU, Portland, Oregon

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Corneal Dystrophy

hmhlbCorneal dystrophy is a term used to describe several conditions in which one or more parts of the cornea have lost their normal clarity. There are over 20 different types of corneal dystrophies, the most common of which are keratoconus and Fuchs' Dystrophy. These diseases have the following common features:

  • They are usually inherited.
  • They affect both eyes.
  • They are not caused from external factors such as injury or diet.
  • Most do not affect other parts of the body.
  • Most are not related to other diseases elsewhere in the body.
  • They can occur in otherwise healthy individuals.
  • Most progress gradually.

Corneal dystrophies affect vision in widely differing ways. Some can cause severe visual impairment, while others may have no noticeable effect on sight. Some individuals with dystrophies may eventually require a corneal transplant to enjoy good vision.

Keratoconus

Typically diagnosed in people in their early teens to mid-twenties, keratoconus is the most common corneal dystrophy in the United States. Keratoconus develops when the central cornea thins and gradually bulges outward in a rounded cone shape. This curvature can produce moderate to severe visual distortion. People with keratoconus tend to become very myopic (nearsighted) and have an irregular, often rapidly fluctuating astigmatism. Keratoconus almost always affects both eyes, although it will usually develop in one eye several months to years before it appears in the second eye. Keratoconus is progressive, meaning it takes several years to develop. It can start at any time and can also stop progressing at any stage. Doctors cannot usually predict how rapidly the condition will progress.

In the early stages of the disease, vision can usually be corrected with glasses or contact lenses. As keratoconus progresses, customized contact lenses may be required to reduce visual distortion. Sometimes the cornea scars cannot tolerate a contact lens. In these cases, a corneal transplant is usually necessary.

Fuchs' Dystrophy (Corneal Dystrophy)

Fuchs' dystrophy is a slowly progressing disease affecting the corneal endothelium (the innermost cells of the cornea). This occurs when the endothelial cells gradually deteriorate and become unable to maintain a fluid barrier between the cornea and the rest of the eye. In this situation, the cornea retains too much fluid. The cornea then swells, altering its curvature and leading to blurry vision. This corneal swelling can also lead to the development of haze within the corneal stroma (the central layer of the cornea) or to the formation of blisters on the corneal surface.

Treatment for Fuchs' dystrophy usually involves drops or ointments intended to decrease the swelling. When medications cease to be effective, a corneal transplant is indicated.