Contributor: Gordon K. Klintworth
Fuchs corneal dystrophy is a bilateral disorder of the corneal endothelium characterized by the presence of multiple cornea guttae and in advanced cases by bullous keratopathy [keratopathy - bullous] as well. Fuchs corneal dystrophy is the commonest corneal dystrophy requiring penetrating keratoplasty in the United States. The condition is rare in some countries, such as Japan and Saudi Arabia. Women are affected >3x as often as men. Fuchs corneal dystrophy is sometimes familial, but its exact mode of inheritance is uncertain. A simple autosomal dominant pattern is unlikely. The cornea becomes edematous due to an accumulation of fluid because of an inability of the corneal endothelium to transport water from its stroma. The abnormal corneal endothelial cells produce cornea guttata of variable shape and size and new collagen which creates a multilaminar markedly thickened Descemet membrane. A simple autosomal dominant pattern is unlikely. Despite being a bilateral disorder the eyes are often affected asymmetrically in Fuchs corneal dystrophy. Fuchs corneal dystrophy gradually progresses to stromal and epithelial edema with subepithelial fibrosis. The clinical course usually extends over 10-20 years and passes through three phases. At first the patient is asymptomatic, but corneal guttae and a fine dusting of pigment is evident on the posterior cornea. Descemet membrane gradually thickens over time. Eventually stromal edma and epithelial edema develop and impair vision and cause the symptoms of glare. Early stromal edema produces a blue-gray haze in the stroma and ultimately the entire corneal stroma thickens and develops a ground glass appearance ground-glass. Subepithelial and intraepithelial vesicles rupture producing painful epithelial erosions. This is followed by pannus formation and a further decrease in visual acuity. Corneal edema is a consequence of the progressive decrease in the function of the corneal endothelium. The abnormal corneal endothelium may undergo fibroblast-like transformation and produce collagen posterior to Descemet membrane. An impaired function of the corneal endothelium allows aqueous humor to penetrate into the corneal stroma and this leads to edema of the corneal epithelium.