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Updated: Jul 19, 2025
Author Spotlight: Isolating Biomolecules from Mouse Tears — A Methodology for Molecular Analysis and Biomarker Research
Published on: July 19, 2024
Randomized comparison of in vivo performance of TearLab® and I-PEN® osmometry in normal dogs
Hyun-Wook Kim1, Joon-Young Kim1,2
1Department of Veterinary Ophthalmology, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Objective:
To compare tear film (TF) osmolarity measured using TearLab® and I-PEN® osmometers in the same dogs without any ocular surface disease.
Animal Studied:
Fifty-two dogs (98 eyes) of different breeds were evaluated.
Procedures:
Tear film (TF) osmolarity was evaluated at 2-min intervals. The test was randomly determined, and single measurements were performed using each osmometer. Subsequently, complete ophthalmologic examinations were performed based on Schirmer tear test-1 (STT-1) analysis, tear film breakup time (TFBUT), and slit-lamp biomicroscopy. For each osmometer, the mean ± standard deviation of the TF osmolarity was calculated, and a paired Student's t-test was used to compare the values obtained. Pearson correlation analysis was performed to assess the association between osmolarity and other values such as STT-1, TFBUT, and age.
Results:
Tear film osmolarity determined using TearLab® (340.42 ± 15.87 mOsm/L) and I-PEN® (321.58 ± 17.39 mOsm/L) were significantly different (p < .001). However, statistical significance could not be confirmed between osmolarity and other values, such as STT-1, TFBUT, and age.
Conclusions:
In dogs, the TF osmolarity values obtained using TearLab® tend to be higher than those obtained using I-PEN®, contrary to that observed in humans. These findings can serve as a reference for establishing normal values for each osmometer for clinical use in measuring TF osmolarity in dogs.
