title: Reference values, intertest correlations, and test-retest repeatability of selected tear film tests in healthy cats.
abstract: OBJECTIVE
  To determine reference values, intertest correlations, and test-retest repeatability of Schirmer tear test 1 (STT-1), phenol red thread test (PRTT), tear film breakup time (TFBUT), tear osmolarity, and meibometry in healthy cats.
  
  
  METHODS
  Evaluation study.
  
  
  METHODS
  135 healthy domestic cats aged 0.5 to 12.8 years.
  
  
  METHODS
  Each test was performed once in 120 cats and repeated in 40. Pearson correlation was used to assess correlation among tests. Intraclass correlation coefficients (ICCs) and 95% limits of agreement (LOA) were used to evaluate test-retest repeatability.
  
  
  RESULTS
  Median (95% central range) values were 18 mm/min (9 to 34 mm/min) for STT-1, 29 mm/15 s (15 to 37 mm/15 s) for PRTT, 12.4 seconds (9.1 to 17.7 seconds) for TFBUT, 322 mOsm/L (297 to 364 mOsm/L) for osmolarity, and 32 meibometry units (MU; 11 to 114 MU) for peak meibometry value. The STT-1 and PRTT values were positively correlated. Age was weakly associated with TFBUT and osmolarity. Meibometry measurements were higher for strips that contacted the tear film (285 MU) than for those that touched the eyelid margin only (32 MU). All ICCs were < 0.75, and 95% LOA were wide.
  
  
  CONCLUSIONS
  Tear deficiency should be suspected in cats with STT-1 < 9 mm/min, PRTT < 15 mm/15 s, or TFBUT < 9 to 10 seconds. Generally poor correlation among tests suggested that thorough tear film analysis requires performance of multiple tests in concert. Relatively poor test-retest repeatability should be considered when repeated tests are used to monitor tear film dysfunction and response to treatment.
authors: William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
authors: Lionel
authors: L
authors: Sebbag
authors: Philip H
authors: PH
authors: Kass
authors: David J
authors: DJ
authors: Maggs
mesh_terms: D000818:Animals; D002415:Cats / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological / Q000662:veterinary*; D005260:Female; D008297:Male; D012016:Reference Values; D013666:Tears / Q000737:chemistry / Q000502:physiology*