Cogan's Dystrophy

Overview

Cogan's dystrophy is an eye condition that affects the outermost layer of the cornea: the corneal epithelium. Though its name suggests that it is an inherited eye disease (ie. “dystrophy”), Cogan's dystrophy can occur without an inherited pattern. Also known as Map Dot Fingerprint Dystrophy or Epithelial Basement Membrane Dystrophy (EBMD), Cogan's dystrophy produces patterns similar to the look of a fingerprint smudge within the cornea. Cogan's dystrophy typically begins to appear in individuals over the age of 30 and becomes progressively worse with age.

In Cogan's dystrophy, the basement membrane of the corneal epithelium becomes thickened and uneven, which then causes the epithelium to lose its ability to adhere properly. As a result, the epithelial cells can slough off, a condition known as corneal erosion. Although these cells can regenerate, it is a painful experience for the individual.

Signs & Symptoms of Cogan's Dystrophy

Symptoms of Cogan's dystrophy vary among individuals: some may experience no symptoms while others may be in excruciating pain. some of the more common symptoms include the following:

light sensitivity
mild to extreme pain and irritation, particularly in the morning upon waking
glare
fluctuating vision
blurred vision

Detection & Diagnosis of Cogan's Dystrophy

Cogan's dystrophy is detected by eye doctors when the layers of the cornea are viewed through a slit lamp biomicroscope. Tiny, microscopic irregularities in the layers of the cornea can be detected under magnification. In cases where Cogan's dystrophy leads to irregular astigmatism, a corneal topographer can be used to evaluate the progression of astigmatism.

Cogan's Dystrophy Treatment

While many patients with Cogan's dystrophy experience no symptoms, approximately 10% develop recurrent corneal erosions (RCE). As such, treatment for Cogan's dystrophy is identical to treatment for RCE: in recent years, laser eye surgery has been used as a tool to fight against recurrent corneal erosions. A laser is used to remove the corneal epithelium and as the cornea regenerates, it develops a better connection with the basement membrane.

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