Fuchs' Corneal Dystrophy

Sunday, December 12, 2010

Fuchs' corneal dystrophy is a genetic, autosomal dominant disease with high penetrance. Fuchs' dystrophy is a degenerative disorder of the corneal endothelium with accumulation of focal excrescences called guttae and thickening of Descemet’s membrane, leading to corneal edema and loss of vision. Corneal endothelial cells are the major pump cells of the cornea which allow for stromal clarity. In the Fuchs' corneal dystrophy, Descemet’s membrane is grossly thickened with accumulation of abnormal wide-spaced collagen and numerous guttae. Corneal endothelial cells in end-stage of the disease are reduced in number and appear attenuated, causing progressive stromal edema.

Progressive endothelial cell loss causes relative influx of aqueous humor into the cornea, leading to swelling (corneal stromal edema), which results in distorted vision. Eventually, the epithelium also becomes edematous, resulting in more severe visual impairment. Focal areas or blisters of epithelial edema ("bullae") may be particularly painful. At first, a person with Fuchs' dystrophy will awaken with blurred vision that will gradually clear during the day. This occurs because the cornea is normally thicker in the morning; it retains fluids during sleep that evaporate in the tear film while we are awake. As the disease worsens, this swelling will remain constant and reduce vision throughout the day.

Medical treatment includes topical hypertonic saline, the use of a hairdryer to dehydrate the precorneal tear film, and therapeutic soft contact lenses. In using a hairdryer, the patient is instructed to hold a hairdryer at an arm's length or directed across the face, to dry out the epithelial blisters. This can be done two or three times a day. Definitive treatment, however, (especially with increased corneal edema) is surgical in the form of corneal transplantation, or penetrating keratoplasty (PKP).