The cornea is the front part of the eye.  Think of it as the crystal on the front of your watch. The cornea, as thick as two business cards, must be transparent to enable clear vision. The cornea has five layers, front to back: Epithelium. Bowman’s layer. Stroma. Descemet’s membrane. Endothelium. With corneal dystrophy, one or more of these layers malfunctions, causing a loss of transparency.  It is inherited, usually bilateral (both eyes). It appears as grayish white lines, circles, or clouding of the cornea.  Corneal dystrophy can also have a crystalline appearance.  Most corneal dystrophies result in swelling of the cornea which may cause painful epithelial blisters during the later stages of the disease.  Corneal dystrophies have typically slow progression through its’ stages. The cure for several of these diseases is a corneal transplant, using a human donor through an eye bank or, as a last result, an artificial cornea.   The most common corneal dystrophy, Fuchs’ Corneal Dystrophy, occurs when endothelial cells gradually deteriorate without any apparent reason.  As more endothelial cells are lost over the years, the endothelium becomes less efficient at pumping water out of the stroma. This  causes the cornea to swell and distort vision. Eventually, the epithelium also takes on water, resulting in pain and severe visual impairment.   Epithelial  swelling damages vision by changing the cornea's normal curvature, and causing a sight-impairing haze to appear in the  tissue. Epithelial swelling will also produce tiny blisters on the corneal surface.  When these blisters burst, they  are extremely painful. At first, a person with corneal dystrophy may 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. When treating the disease, doctors will try first to reduce the swelling with  drops, ointments,  or ’bandage contact lenses’.  They also may instruct a person to  use a hair dryer, held at arm's length, directed sideways, across the face, to dry out the epithelial blisters.  This can be done two or three  times a day. When the disease interferes with one’s quality of life or daily activities, one  may need to  consider having a corneal transplant to restore sight.

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