The corneal epithelium produces and adheres to its underlying basement membrane. Deeper epithelial cells that normally migrate to the surface can become trapped. Epithelial cells anterior to aberrant basement membrane may have difficulty forming viable hemidesmosome 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. Others experience painful recurrent erosions, decreased vision or both. The majority of patients are asymptomatic. Visual symptoms are usually mild and occasionally debilitating. Vision is variable and fluctuating due to migratory and intermittent corneal involvement.