Clinical, electron microscopic, and monoclonal antibody studies of intraocular epithelial downgrowth.

Epithelial downgrowth developed in three patients following cataract extraction and keratoplasty. Light and electron microscopy of the downgrowth tissue disclosed stratified squamous epithelium, but could not determine whether they were derived from conjunctival or corneal epithelium. The epithelial downgrowth contained cells that were connected laterally by desmosomal junctions and displayed well-defined basement membranes. Surface epithelial cells exhibited myriad microvillous processes scant to moderate mitochondria. In one case, prominent hemidesmosomal junctions were present. Immunohistochemical staining with monoclonal antikeratin antibodies revealed immunoreactivity with AE1, AE3, and AE11 in all cases, but with a cornea-specific antibody, AE5, in only one case. We concluded that in this last case, the epithelial downgrowth appears to have originated from the corneal epithelium.