Corneal biopsy specimens from four patients with disorders of the corneal epithelium were examined by light and electron microscopy. The samples were taken from corneas showing the fingerprint, geographic, or map-like and microcystic varieties of epithelial disturbance. All varieties produced abnormal quantities of multilaminar basement membrane, most striking clinically in the fingerprint epithelial disorders. In the geographic or map-like pattern the epithelium produced somewhat more equal quantities of multilaminar basement membrane and collagenous tissue in placoid or mushroom forms beneath the epithelium. In the microcystic variety, an inverted basal cell layer continues to proliferate, and the flattened "surface" cells desquamate into an intraepithelial pocket or "cyst." In one variety of geographic configuration a large quantity of material of unknown composition, presumably of keratocytic origin, accumulated between a thick, normally positioned multilaminar basement membrane and Bowman layer.
Rodrigues MM, Fine BS, Laibson PR, Zimmerman LE. Disorders of the Corneal EpitheliumA Clinicopathologic Study of Dot, Geographic, and Fingerprint Patterns. Arch Ophthalmol. 1974;92(6):475-482. doi:10.1001/archopht.1974.01010010489005