title: Tear-film osmolarity in normal cats and cats with conjunctivitis.
abstract: OBJECTIVE
  To compare the tear-film osmolarity of normal cats and cats with conjunctivitis.
  
  
  METHODS
  The population consisted of shelter, research, and privately owned cats.
  
  
  METHODS
  Cats were classified as normal or having conjunctivitis. An ophthalmic examination including Schirmer tear test (STT), fluorescein staining, tear-film break-up time (TFBUT), intraocular pressure (IOP), and slit-lamp biomicroscopy of the anterior segment was performed. The severity of conjunctivitis was graded and assigned a numerical score. The Tear Lab(TM) Osmolarity System was utilized to determine the tear-film osmolarity. Unpaired t-tests were used to compare tear-film osmolarity, TFBUT, IOP, and STT of the two groups.
  
  
  RESULTS
  A total of 93 cats (186 eyes) were examined. There were 37 normal cats (74 eyes) and 39 conjunctivitis cats (78 eyes). The mean age was 2.34 years. There was no statistical difference (P = 0.2065) between the median tear-film osmolarity of normal cats (328.5 ± 17.94 mOsms/L) and conjunctivitis cats (325.0 ± 24.84 mOsms/L). Cats with conjunctivitis had an accelerated TFBUT (P < 0.0001) and lower IOPs (P < 0.0001) as compared to normal cats. No statistical difference was found between STT values (P = 0.1304).
  
  
  CONCLUSIONS
  The median tear-film osmolarity of normal cats was 328.5 mOsms/L. Despite the accelerated TFBUT, conjunctivitis did not cause a statistically significant change in tear-film osmolarity. The Tear Lab(TM) Osmolarity System was easily used and well tolerated by the cats in the study.
authors.affiliation: Department of Small Animal Clinical Sciences, Michigan State University, College of Veterinary Medicine, E. Lansing, MI, USA.
authors.forename: Kyshia
authors.initials: K
authors.lastname: Davis
authors.forename: Wendy
authors.initials: W
authors.lastname: Townsend
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000503:physiopathology*; D002415:Cats; D003231:Conjunctivitis / Q000503:physiopathology / Q000662:veterinary*; D005260:Female; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D009994:Osmolar Concentration; D012720:Severity of Illness Index; D013666:Tears / Q000502:physiology*