title: [Studies on the precorneal tear film. First communication: an optical system for demonstrating tear film without fluorescein (author's transl)].
abstract: Tear film is usually studied by using fluorescein. An optical system is described which despenses with the use of fluorescein. It mainly consists in an equal diffuse illumination of the cornea, provided through an opaque truncated cone that is illuminated from behind. The cone is situated as close as possible to the front of the eye. The cornea and its surface can be observed through a hole at the narrow end of the cone. Interferences in the lipid layer of the tear film are recognizable as "colors of thin layers". The physical background to interferences in thin, convex layers is discussed. Break-ups are visualized by using a supplementary "Schlieren" method.
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D008433:Mathematics; D055095:Optics and Photonics; D013666:Tears / Q000502:physiology*
vernacular_title: Studien über den präkornealen Tränenfilm (PKTF). 1. Mitteilung. Ein optisches Verfahren zur Darstellung des Tränenfilms ohne Fluoreszein.