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Assessment of tear film osmolarity using the TearLab ™ osmometer in normal dogs and dogs with keratoconjunctivitis sicca
Author(s) -
Sebbag Lionel,
Park Shin Ae,
Kass Philip H.,
Maggs David J.,
Attar Mayssa,
Murphy Christopher J.
Publication year - 2017
Publication title -
veterinary ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.594
H-Index - 50
eISSN - 1463-5224
pISSN - 1463-5216
DOI - 10.1111/vop.12436
Subject(s) - repeatability , osmometer , osmotic concentration , reproducibility , beagle , osmole , ophthalmology , keratoconjunctivitis sicca , medicine , chemistry , chromatography
Objective To evaluate repeatability and reproducibility of tear osmolarity measured using the TearLab ™ osmometer in normal dogs and to assess its diagnostic potential in dogs with keratoconjunctivitis sicca ( KCS ). Animals studied Beagle dogs; six normal and five with KCS . Procedures Tear osmolarity and Schirmer tear test‐1 ( STT ‐1) values were obtained at various times. Normal dogs were assessed for diurnal variation and repeatability and reproducibility of measurements. Dogs with KCS were evaluated before and after 5 months’ topical twice‐daily therapy with 2% cyclosporine. Results Mean ± SD tear osmolarity ( mO sm/L) was significantly higher in normal dogs (337.4 ± 16.2) than in dogs with KCS before therapy (306.2 ± 18.0; P < 0.0001), but not following therapy with 2% cyclosporine (330.5 ± 13.7; P = 1.00). Osmolarity readings lower than 325.5 mOsm/L were suggestive of KCS (84.8% sensitivity and 87.1% specificity). In normal dogs, tear osmolarity readings were stable during the daytime ( P = 0.99). Repeated measurements revealed high variability and typically poor‐to‐moderate repeatability and reproducibility, although this was improved by taking three successive measurements at each session. Considering combined data from all dogs, a positive correlation existed between STT ‐1 and tear osmolarity measurements (Pearson's correlation test, P = 0.04, r = 0.62). Conclusions Canine tear osmolarity as determined by TearLab ™ osmometer was variable, required multiple readings to be informative, and differed from values reported for humans. Dogs with KCS had a lower tear osmolarity than did normal dogs, and this increased following cyclosporine therapy.