title: Tears in health and disease.
abstract: OBJECTIVE
  A brief review of normal tear function and changes resulting from disease.
  
  
  METHODS
  The factors contributing to normal tear physiological function are considered, and the effect of changes in composition, as reported in the literature, is surveyed, with emphasis on the physical performance of the tears. Major classes of tear tests which would reveal functional changes are listed.
  
  
  RESULTS
  Where possible, changes of measurable functions in disease are described. Gaps in our current knowledge are indicated.
  
  
  CONCLUSIONS
  Many techniques exist for examination and assessment of both normal and disease tears, but further development is needed to adapt some of these to clinical situations, and to make them more specific diagnostic tests.
authors: Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK. john.tiffany@eye.ox.ac.uk
authors: J M
authors: JM
authors: Tiffany
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007766:Lacrimal Apparatus Diseases / Q000175:diagnosis*; D013666:Tears / Q000737:chemistry / Q000502:physiology*