A corneal dystrophy is characterized as the gradual deterioration of one of the layers of the cornea. The multi-layered cornea is the central transparent outer layer of the eye through which light enters. There are a variety of corneal dystrophies that can affect one of the layers of the cornea. Dystrophies are most often inherited and can occur at an early age, even at birth. The two most common are epithelial basement membrane dystrophy and endothelial cell dystrophy.

Epithelial basement membrane dystrophy affects the surface layer of the cornea and it is often referred to as map-dot, or fingerprint dystrophy. It generally occurs in adults after the age of 40, and it can come as late as age 70. In this form of dystrophy, the basement membrane begins to become thick and irregular, so that the once-even layer of cells starts to buckle as the cells break apart and fall off the membrane. The breakdown of the basement membrane in epithelial dystrophy causes redness of the eye and discomfort that can range from moderate irritation to severe pain. Those symptoms generally are worse at the start of the day, because sleep does not permit the blinking that keeps the surface of the cornea lubricated with tears. Treatment usually starts with efforts to enhance the natural lubrication, using artificial tears and eye drops applied periodically during the day and just before sleep. A patient may be told to wear a customized eye patch or a special contact lens to achieve the necessary healing and lubrication. Measures to keep the home environment more humid, using vaporizers may be recommended. In severe cases, surgical scraping of the superficial layers of the cornea may help rebuild the integrity of the cells and reduce symptoms.

Endothelial cell dystrophy affects the inner layer of the cornea and it is often called Fuch's dystrophy. It is most common in adults in their middle years and affects women more than men. It too tends to be hereditary, and it generally affects both eyes. Fuch's dystrophy occurs when the natural pumping activity of the inner endothelium cells begin to deteriorate. Excess fluid starts to accumulate, causing the cornea to become swollen and less transparent, so that visual ability can deteriorate with time. As a result, the most noticeable symptom of corneal endothelial cell dystrophy is blurry vision. This is particularly evident at wake-up time because while the eyes are closed during sleep, less fluid is able to evaporate. Vision improves as the day goes on, as more fluid evaporates. To treat endothelial cell dystrophy, steps are taken to remove moisture from the eyes, using specific ointments and eye drops. In very progressive severe cases, a corneal transplant may be considered.