dystrophy: A disorder in which the cornea (the normally
clear front window of the eye) shows dots (or microcysts), geographic map-like
lines, and grayish fingerprint lines on examination with a slit-lamp, a device that focuses a high intensity light beam as a slit while the examiner looks at the front of the eye through a magnifying scope.
The disorder is usually silent and without symptoms.
However, about one patient in ten has recurrent erosion of the cornea that usually begins after the age 30.
Conversely, half of patients with recurrent corneal
erosions of idiopathic (unknown) origin have this disorder.
Under the microscope, a structure called the epithelial
basement membrane is
abnormal. The disorder is therefore sometimes called epithelial basement corneal
The disorder was first described by Cogan and colleagues
in 1964. Hence, the name: Cogan corneal dystrophy. It is also known, to add to
the confusion, as map-dot-fingerprint type corneal dystrophy.