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Veterinary world2024; 17(2); 384-388; doi: 10.14202/vetworld.2024.384-388

Comparison of Tonovet® and Tonovet plus® tonometers for measuring intraocular pressure in dogs, cats, horses, cattle, and sheep.

Abstract: Reference ranges for intraocular pressure (IOP) in healthy animals are device-specific; therefore, it is strongly recommended to use appropriate reference values according to the device. Therefore, our aim was to compare IOP readings made by TonoVet® and TonoVet Plus® in healthy dogs, cats, sheep, cattle, and horses. We compared IOP values measured by TonoVet® and TonoVet Plus® tonometers in clinically normal eyes of dogs, cats, horses, cattle, and sheep. Unassigned: Five groups comprising 20 animals each of dogs (various breeds, 9 months-10 years old, 14 females, 6 males), cats (various breeds, 6 months-12 years old, 8 females, 12 males), horses (various breeds, 5-12 years old, 12 females, 8 males), cattle (Holstein, 1-7 lactation, female), and sheep (Latvian Darkhead ewes, 1-8 years old) were included in the study. Both eyes of all animals were subjected to ophthalmic examination, including evaluation of IOP by rebound tonometry using TonoVet® and TonoVet Plus® devices. Normality was determined using the Shapiro-Wilk test. The independent t-test was used to determine differences between IOP values in the right and left eyes and between both tonometers. This study was approved by the Ethical Commission of the Latvia University of Life Sciences and Technologies (Nr. LLU_Dzaep_2022-2-4). Unassigned: No differences in IOP between the right and left eyes were found in all cases (p > 0.05). The mean IOP ± standard deviation values in both eyes for TonoVet® and TonoVet Plus® tonometers were as follows: for dogs, 15.25 ± 2.73 mmHg and 19.65 ± 3.46 mmHg; and in cats, 18.88 ± 3.98 mmHg and 18.78 ± 4.26 mmHg, respectively. In horses, mean IOP was 22.15 ± 3.74 mmHg and 24.28 ± 3.00 mmHg; in cattle, 24.73 ± 2.89 mmHg and 23.28 ± 2.97 mmHg; and in sheep, 18.05 ± 3.54 mmHg and 22.49 ± 4.66 mmHg, respectively. Significant differences in IOP values were observed between the tonometers in sheep, dog, and horse groups (mean difference -4.40, -4.48, and 2.13, respectively). Unassigned: This study showed significantly higher IOP values measured by the TonoVet Plus® tonometer in dogs and sheep.
Copyright: © Kovalcuka, et al.
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Publication Date: 2024-02-16 PubMed ID: 38595645PubMed Central: PMC11000490DOI: 10.14202/vetworld.2024.384-388Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This research compared intraocular pressure (IOP) readings taken with two different rebound tonometers, the TonoVet® and TonoVet Plus®, across several common domestic animal species to determine if device-specific reference values are needed.
  • The study found significant differences in IOP measurements between the two devices in some species, emphasizing the importance of using device-specific reference ranges when evaluating eye pressure in animals.

Study Purpose

  • The main goal was to compare IOP values measured by the TonoVet® and the newer TonoVet Plus® devices in healthy dogs, cats, horses, cattle, and sheep to assess if readings differ between these tonometers.
  • Since normal IOP values can vary depending on the measurement device, establishing whether these two tonometers give comparable results is essential to ensure proper clinical interpretation.

Subjects and Methods

  • The study included five groups of domesticated animals, each consisting of 20 clinically healthy individuals:
    • Dogs: Various breeds, aged 9 months to 10 years, 14 females and 6 males
    • Cats: Various breeds, aged 6 months to 12 years, 8 females and 12 males
    • Horses: Various breeds, aged 5 to 12 years, 12 females and 8 males
    • Cattle: Holstein breed, female, lactation 1-7 times
    • Sheep: Latvian Darkhead ewes, aged 1 to 8 years
  • Both eyes of all animals were examined using ophthalmic techniques and IOP was measured via rebound tonometry, first with the TonoVet® and then with the TonoVet Plus® device for comparison purposes.
  • Statistical analyses included:
    • Shapiro-Wilk test to check data normality
    • Independent t-tests to compare IOP values:
      • Between the right and left eyes within each animal
      • Between measurements obtained by the two tonometer devices
  • The study had ethical approval from the Latvia University of Life Sciences and Technologies Ethical Commission.

Results

  • No significant differences were found in IOP values between the right and left eyes within any animal group (p > 0.05), justifying average use of both eyes for device comparison.
  • Mean IOP ± standard deviation readings for both eyes measured using the two devices were:
    • Dogs: TonoVet® 15.25 ± 2.73 mmHg vs. TonoVet Plus® 19.65 ± 3.46 mmHg
    • Cats: TonoVet® 18.88 ± 3.98 mmHg vs. TonoVet Plus® 18.78 ± 4.26 mmHg
    • Horses: TonoVet® 22.15 ± 3.74 mmHg vs. TonoVet Plus® 24.28 ± 3.00 mmHg
    • Cattle: TonoVet® 24.73 ± 2.89 mmHg vs. TonoVet Plus® 23.28 ± 2.97 mmHg
    • Sheep: TonoVet® 18.05 ± 3.54 mmHg vs. TonoVet Plus® 22.49 ± 4.66 mmHg
  • Statistically significant differences in IOP values between devices were found in dogs, sheep, and horses, with mean differences of approximately:
    • Dogs: -4.48 mmHg (TonoVet® reading lower than TonoVet Plus®)
    • Sheep: -4.40 mmHg (TonoVet® lower)
    • Horses: +2.13 mmHg (TonoVet® higher)
  • No significant differences were observed in cats and cattle.

Conclusions and Implications

  • The TonoVet Plus® tonometer yielded significantly higher IOP measurements than the TonoVet® in dogs and sheep, but not in cats or cattle, and slightly higher values in horses (which were statistically significant in the opposite direction).
  • These differences highlight that IOP reference ranges should be device-specific to avoid misinterpretation of an animal’s ocular pressure status.
  • Clinicians and researchers interpreting IOP in these species should be aware of the particular tonometer used and apply appropriate reference values accordingly, ensuring better diagnosis and management of ocular conditions.
  • The study reinforces the need for device validation in veterinary ophthalmology before broadly applying IOP results for clinical decision-making.

Cite This Article

APA
Kovalcuka L, Mālniece A, Vanaga J. (2024). Comparison of Tonovet® and Tonovet plus® tonometers for measuring intraocular pressure in dogs, cats, horses, cattle, and sheep. Vet World, 17(2), 384-388. https://doi.org/10.14202/vetworld.2024.384-388

Publication

Veterinary world
ISSN: 0972-8988
NlmUniqueID: 101504872
Country: India
Language: English
Volume: 17
Issue: 2
Pages: 384-388

Researcher Affiliations

Kovalcuka, Liga
  • Clinical Institute, Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, Jelgava, LV-3004, Latvia.
Mālniece, Aija
  • Clinical Institute, Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, Jelgava, LV-3004, Latvia.
Vanaga, Jana
  • Clinical Institute, Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, Jelgava, LV-3004, Latvia.

Conflict of Interest Statement

The authors declare that they have no competing interests.

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Citations

This article has been cited 3 times.
  1. Voiko L, Vekšins A, Birnere D, Kovalcuka L. Canine intraocular pressure dynamics during mild-pain ophthalmic procedures in three premedication protocols.. Vet World 2025 Mar;18(3):573-581.
    doi: 10.14202/vetworld.2025.573-581pubmed: 40342739google scholar: lookup
  2. Bakula M, Kuzman T, Radoš M, Starčević K, Jurjević I, Mamić M, Pirkić B, Klarica M. Control values of intraocular pressure in different species: a review of literature.. Croat Med J 2024 Dec 30;65(6):518-529.
    doi: 10.3325/cmj.2024.65.518pubmed: 39812101google scholar: lookup
  3. Kovalcuka L, Malniece A. Measurement of Tear Production and Intraocular Pressure in Clinically Conscious Normal Captive Red Deer (Cervus elaphus).. Animals (Basel) 2024 Mar 19;14(6).
    doi: 10.3390/ani14060940pubmed: 38540037google scholar: lookup
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