Epithelial transformation of the corneal endothelium in forceps birth-injury-associated keratopathy.

Using light and electron microscopy, we studied four keratectomy specimens obtained by penetrating keratoplasty from four patients (ages 33-54 years; mean age: 43 years old) who had clinical evidence of Descemet's folds and bullous keratopathy after ruptures in Descemet's membrane after forceps injury at birth. Histopathologically, three patients showed the typical features of forceps birth injury: Descemet's membrane at the margin of the rupture was folded and assumed a scroll-shape configuration. The fourth patient showed clusters of proliferated endothelial cells at the site of two ruptures, and from one site of the ruptures, these cells invaded into Descemet's membrane, forming a new basement membrane. Transmission electron microscopy revealed that these proliferated cells were epithelial-like cells characterized by desmosomal junctions, basal lamina, numerous microvilli, and 8-nm cytoplasmic filaments. The epithelial transformation of the corneal endothelium was identified in cases of posterior polymorphous dystrophy and assumed to be specific for this entity. The findings in our fourth patient represent the first documentation of epithelial-like cells on the posterior corneal surface in forceps birth-injury-associated keratopathy. Our results suggest that epithelial transformation may be a nonspecific reaction of the young cornea to various stimuli.