Excerpt from Dystrophy, Map-dot-fingerprint

Synonyms, Key Words, and Related Terms: map-dot-fingerprint dystrophy, anterior basement membrane dystrophy, epithelial basement membrane dystrophy, Cogan's microcystic dystrophy, slit lamp, corneal dystrophy, corneal degeneration

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Background: Corneal map-dot-fingerprint dystrophy is by far the most common corneal dystrophy and is named from the appearance of its characteristic slit lamp findings. Map-dot-fingerprint dystrophy also is known as epithelial basement membrane dystrophy, and Cogan microcystic epithelial dystrophy. It usually is classified as a dystrophy but fits more accurately into the corneal degeneration category.

Corneal dystrophies usually are hereditary, bilateral, progressive, and not associated with systemic or local disease. Map-dot-fingerprint dystrophy has been found in several families with a presumed autosomal dominant pattern, but in most cases, it is not familial. It is not progressive but rather variable and fluctuating in its course. Usually, it is bilateral but can be unilateral or very asymmetric in presentation.

Pathophysiology: The corneal epithelium produces and adheres to its underlying basement membrane. Corneal abnormalities associated with map-dot-fingerprint dystrophy are the result of a faulty basement membrane, which is thickened, multilaminar, and misdirected into the epithelium. Deeper epithelial cells that normally migrate to the surface can become trapped. Epithelial cells anterior to aberrant basement membrane may have difficulty forming viable hemidesmosomes and basement membrane complexes, which attach to the underlying stroma, resulting in recurrent erosions. Irregular epithelium centrally can cause decreased vision.

Maps histologically represent areas of multilaminar basement membrane, which extend into the epithelium. Dots are intraepithelial microcysts that contain nuclear, cytoplasmic, and lipid debris. Fingerprints are curvilinear clusters of reduplicated and thickened basement membrane and fibrillogranular material. Blebs, a less common manifestation of map-dot-fingerprint dystrophy, are localized areas of fibrillogranular material or thickened basement membrane.

Frequency:

In the US: Estimates of the prevalence of map-dot-fingerprint dystrophy range from 2-43% of the general population. Of patients with map-dot-fingerprint dystrophy, 10-33% have recurrent corneal erosions. As many as 50% of patients with recurrent corneal erosions have map-dot-fingerprint dystrophy.

Mortality/Morbidity: Patients with map-dot-fingerprint dystrophy may be asymptomatic. Others experience painful recurrent erosions, decreased vision, or both.

Sex: This condition is slightly more common in females than in males.

Age: This condition is uncommon in children.