Rigid contact lenses were fitted on primates to study the subsequent corneal epithelial injury. This trauma was compared to corneal abrasions produced by a blunt object. The traumatic abrasion caused a rupture of the basal cells, which were identified as the most vulnerable part of the corneal epithelium for such an injury. The internal plasmalemma of the basal cell remained adherent to the epithelial basement membrane due to the strong hemidesmosomes along the cell membrane. Contact lenses were capable of producing similar injuries which did not penetrate the basement membrane and therefore did not involve the anterior limiting lamina (Bowman's membrane). We concluded that contact lenses produce a self-limiting trauma and even a severe case of contact lens overwear, although it causes deep corneal abrasions, seldom results in permanent scar formation.