title: Dynamics of tear fluid desiccation on a glass surface: a contribution to tear quality assessment.
abstract: BACKGROUND
  Fern-like crystalloids form when a microvolume of tear is allowed to dry out at ambient conditions on a glass surface. Presence of crystalloids in tear "microdesiccates" is used to evaluate patients with Dry-Eye disease. This study aims to examine morphologically the desiccation process of normal tear fluid and to identify changes associated with accelerated tear evaporation. Tear microdesiccates from healthy (Non-Dry Eye) and Dry Eye subjects were produced at ambient conditions. Microdesiccate formation was monitored continuously by dark-field video microscopy. Additionally, accelerated desiccation of tear samples from healthy subjects was conducted under controlled experimental conditions. Particular morphological domains of tear microdesiccates and their progressive appearance during desiccation were compared.
  
  
  RESULTS
  In normal tear microdesiccates, four distinctive morphological domains (zones I, II, III and transition band) were recognized. Stepwise formation of those domains is now described. Experimentally accelerated desiccation resulted in marked changes in some of those zones, particularly involving either disappearance or size reduction of fern-like crystalloids of zones II and III. Tear microdesiccates from Dry Eye subjects may also display those differences and be the expression of a more synchronous formation of microdesiccate domains.
  
  
  CONCLUSIONS
  Morphological characteristics of tear microdesiccates can provide insights into the relative rate of tear evaporation.
authors.forename: Leonidas
authors.initials: L
authors.lastname: Traipe-Castro
authors.forename: Daniela
authors.initials: D
authors.lastname: Salinas-Toro
authors.forename: Daniela
authors.initials: D
authors.lastname: López
authors.forename: Mario
authors.initials: M
authors.lastname: Zanolli
authors.forename: Miguel
authors.initials: M
authors.lastname: Srur
authors.forename: Felipe
authors.initials: F
authors.lastname: Valenzuela
authors.forename: Aníbal
authors.initials: A
authors.lastname: Cáceres
authors.forename: Héctor
authors.initials: H
authors.lastname: Toledo-Araya
authors.forename: Remigio
authors.initials: R
authors.lastname: López-Solís
mesh_terms: D000328:Adult; D003460:Crystallization; D003890:Desiccation; D015352:Dry Eye Syndromes / Q000175:diagnosis; D005898:Glass; D006801:Humans; D057446:Hydrodynamics; D018715:Microscopy, Video; D008875:Middle Aged; D013666:Tears / Q000737:chemistry*