Corneal superficial unwettable defect. I. Clinical and histopathological study.

In 11 patients, the clinical, histological and histochemical picture of an unusual corneal affection termed "corneal superficial unwettable defect", is reported. It develops during the healing of various corneal lesions. Clinically, it is described as a defect of the epithelium with a denuded and changed Bowman's membrane, the surface of which repells tears and cannot be stained with fluorescein. In the histological picture, the changed Bowman's membrane has fibrillar or foamy appearence. It stains strongly with colloidal iron and alcian blue, but PAS and toluidine blue reactions are weak. Histochemical reactions for neutral fats are strongly positive, but those for phospholipids are negative. The results of extractions speak for the presence of some lipid component, which is neither neutral fat nor phospholipid. Hence it is supposed that there may be some waxes-ointment bases, reacting with the pathologically changed Bowman's membrane. The possible mechanisms injuring or influencing the Bowman's membrane are also discussed.