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Julie Ann Kiland, Abby Rothering, Shawna Gloe, Gillian J McLellan; Validation of the Icare® TONOVET Plus rebound tonometer in normal rabbit eyes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2427.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the accuracy and precision of the Icare® TONOVET Plus (Icare Oy, Finland), an updated model of the TONOVET®, in normal rabbits.
The anterior chambers of both eyes of 3 young, adult New Zealand White rabbits (n=6 eyes) were cannulated in situ within 5 hours post-mortem. Manometric IOP was initially set at 5 mmHg and then increased in 5 mmHg increments to 40 mmHg and then in 10 mmHg increments to 70 mmHg, by raising the height of a fluid reservoir. Triplicate instrument-derived IOP values obtained at each increment using the TONOVET Plus® (rabbit setting) were compared to manometrically set IOPs and to IOPs obtained with 3 other commercially available handheld tonometers: the original TONOVET® (‘d’ setting), Tono-Pen Vet™, and Tono-Pen Avia™. Data were analyzed by linear regression; ANOVA followed by Tukey post-tests, and Bland-Altman plots. A p-value ≤0.05 was considered statistically significant.
All tonometers showed linear trends when plotted against manometric IOP, but IOP values obtained in rabbit eyes using the TONOVET Plus® were significantly more accurate compared to those obtained with the TONOVET®, Tono-Pen Vet™, and Tono-Pen Avia™ (p<0.0001, p<0.0001, p<0.05, respectively). No significant differences in precision were found when comparing the TONOVET Plus® to the TONOVET® or Tono-Pen Vet™, however, both the TONOVET Plus® and the TONOVET® were significantly more precise than the Tono-Pen AVIA™ (p<0.05). All tonometers tended to underestimate IOP, though magnitude of this underestimation was far less with the TONOVET Plus® (Figure 1).
TONOVET Plus®, which incorporates a species-specific calibration setting for rabbits, provided accurate and precise IOP values in rabbits, particularly in the clinically relevant range of 5-50 mmHg. The TONOVET Plus® represents a significant improvement in accuracy over other commercially available tonometers when measuring IOP non-invasively in rabbits in research, toxicology and veterinary clinical settings. However, values obtained with the TONOVET Plus® and with its predecessor, the TONOVET, are not interchangeable.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Linear regression of IOPs obtained with the Icare® TONOVET Plus, TONOVET®, Tono-Pen Vet™, and Tono-Pen AVIA™ plotted against the manometric pressures. y=x line shown for reference of true pressures.
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