Background
Corneal map-dot-fingerprint dystrophy is by far the most common corneal dystrophy and is named for the appearance of its characteristic slit-lamp findings. Map-dot-fingerprint dystrophy is also known as epithelial basement membrane dystrophy, anterior basement membrane dystrophy, and Cogan microcystic epithelial dystrophy. [1, 2, 3, 4, 5]
Historically, corneal dystrophies are usually described as hereditary, bilateral, progressive, and not associated with systemic or local disease. However, in most cases, map-dot-fingerprint dystrophy is sporadic and may be a degenerative rather than familial condition. [6] Map-dot-fingerprint dystrophy is also not progressive but rather variable and fluctuating in its course. Map-dot-fingerprint dystrophy is usually bilateral, but it can be unilateral or very asymmetric in presentation. [7]
According to the International Committee for Classification of Corneal Diseases (IC3D), corneal dystrophies are still classified by the anatomic layer of corneal involvement, but they are increasingly defined on a genetic basis. Map-dot-fingerprint dystrophy was reclassified in 2015 as a degenerative condition in the majority of cases, with rare cases considered hereditary and class 1 ("a well-defined corneal dystrophy in which the gene has been mapped and identified and the specific mutations are known"). [8] Map-dot-fingerprint dystrophy has been associated in several families with a presumed autosomal-dominant pattern attributed to the TGFBI gene, locus 5q31. [9, 10, 11]
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. [12] 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.
Epidemiology
Frequency
United States
Estimates of the prevalence of map-dot-fingerprint dystrophy range from 2-43% of the general population. [13] 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. [14, 15]
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.
Prognosis
Map-dot-fingerprint dystrophy findings may fluctuate but tend not to progress over time. Most patients are able to maintain sufficient vision and comfort for reading, driving, and other visual tasks, except during episodes of corneal erosions.
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Corneal maps. Best seen with broad illumination beam.
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Corneal dots. Cluster of corneal dots.
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Corneal fingerprints. Best seen in retroillumination.
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Pseudofingerprints (shift lines) in a patient with Fuchs corneal dystrophy.
