Ultrastructural studies were done on a cornea obtained at the time of
lamellar keratoplasty from a patient with the clinical diagnosis of Meesmann's
corneal dystrophy. Light microscopy showed in the corneal epithelium the typical tiny
cysts containing cellular debris and a homogeneous substance that reacted with
periodic acid and
Schiff's reagent and stained with Hale's colloidal
iron; as well, the basement membrane was markedly thickened. Electron microscopy revealed that the
cysts had a corrugated or microvillous wall, consistent with
acantholysis. The epithelial cells were rich in
glycogen, and many contained the peculiar substance described by others in Meesmann's
corneal dystrophy. This substance appeared to be derived from the tonofilaments and was in close relation to the desmosomes. The thick basement membrane showed secondary changes, with one thick zone that was rich in
collagen fibrils mimicking abnormal anchoring fibrils and one thin zone that was poor in fibrils but had frequent intercalated fibroblasts and probably represented a repair phenomenon. There was no apparent modification of Bowman's layer or the superficial stroma.