[Impression cytology as a noninvasive method of conjunctival biopsy and its results]

Impression cytology is a non-invasive, repeatable, and uncomplicated method of examining the conjunctiva. Cellulose-acetate filters are used to remove the superficial layers of the conjunctiva. This technique causes no subjective discomfort to the patient. The method combines the advantages of a biopsy with those of a "Häutchenpräparat." The authors used 3 different stains for the conjunctival imprints: PAS-hematoxylin, Alcian blue and a combination of Alcian blue and PAS. From the different staining characteristics of the goblet cells it was possible to draw conclusions about different functional cell conditions. The metachromatic properties of a few cells among the large number of epithelial cells led to speculation on the existence of different cell types and their possible correlation with the various cell types described by Rohen for the conjunctiva of monkeys. In patients with keratoconjunctivitis sicca or Sjögren's syndrome pathologic nuclear changes occur that lead to chromatin taking on a snake-like appearance, the so-called "snakes." To the authors' surprise, similar chromatin changes were found in a great number of cells of contact lens wearers, with frequency depending on the type of contact lens. Impression cytology is a special method of non-invasive biopsy providing new possibilities for diagnosis, differential diagnosis, and therapeutic control of conjunctival disorders.