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Veterinary ophthalmology2023; 26(6); 555-559; doi: 10.1111/vop.13142

Validation of a novel rebound tonometer (Tono-Vera® Vet) in normal ex vivo rabbit eyes.

Abstract: The purpose of this study was to validate the use of the Reichert Tono-Vera® Vet tonometer rabbit setting in normal ex vivo rabbit eyes and to compare the rabbit setting to the dog, cat, and horse settings of this tonometer. Methods: Six freshly enucleated normal rabbit eyes were cannulated and connected to a fluid reservoir and physiologic monitor. Triplicate measurements were obtained with the four available settings: dog, cat, horse, and rabbit at various intraocular pressures (IOP) ranging from 5 to 80 mmHg. Bland-Altman analysis was utilized to determine bias and 95% limits of agreement for each setting. Results: Linear regression equations for the dog, horse, cat, and rabbit settings were y = 0.8101x + 2.5058, y = 0.7594x - 3.4673, y = 0.6635x + 0.3021, and y = 0.8935x + 1.3295, respectively. All settings demonstrated strong positive linear trends (dog r2  = 0.9644, horse r2  = 0.9456, cat r2  = 0.9309, and rabbit r2  = 0.9558). Bland-Altman plots revealed that the average bias and 95% limits of agreement (mmHg) were -4.73, -12.65, -12.86 and -2.73 and (-15.31, 5.86), (-29.03, 3.74), (-25.67, -0.05), and (-12.21, 6.76) for the dog, horse, cat, and rabbit settings, respectively. Conclusions: The Tono-Vera® Vet rabbit setting provided the most accurate and precise measurements compared with the other settings, but slightly underestimated actual IOP, especially as IOP was increased. This tonometer, using the rabbit setting, is likely to be appropriate for the estimation of IOP in rabbits with the appropriate correction formula applied.
© 2023 American College of Veterinary Ophthalmologists.
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Publication Date: 2023-09-01 PubMed ID: 37658477DOI: 10.1111/vop.13142Google 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.

This study tested a tool called the Tono-Vera® Vet tonometer for measuring eye pressure in rabbits. The researchers found that, while all settings of the tool showed a positive relationship with intraocular pressure (pressure within the eye), the rabbit-specific setting provided the most accurate measurements.

Research Methodology

  • The study was conducted on six freshly removed, normal rabbit eyes. The eyes were cannuated (a thin tube inserted for fluid discharge or injection) and connected to a fluid reservoir and monitor to study physiologic responses.
  • The intraocular pressure (IOP) in the eyes was varied from 5 to 80 mmHg to cover a broad range of potential scenarios.
  • With each of the four settings available on the Tono-Vera® Vet tonometer (dog, cat, horse, and rabbit), triplicate measurements were recorded at each IOP level.
  • Finally, to calculate the bias and the confidence interval for each setting, Bland-Altman analysis was performed.

Research Findings

  • The linear regression equations for dog, horse, cat, and rabbit settings demonstrated strong positive linear trends, indicating a high correlation between the Tono-Vera® Vet tonometer measurements and actual IOP.
  • The Bland-Altman plots revealed that the rabbit setting had the least average bias and smallest limits of agreement compared to other settings. However, it was observed that the rabbit setting tends to slightly underestimate the actual IOP, particularly as IOP is increased.
  • Despite some degree of underestimation, the rabbit setting was identified as the most accurate on this particular tonometer. This underestimation can be corrected using the appropriate formula.

Conclusion

  • The Tono-Vera® Vet tonometer, when used with its rabbit setting, is likely an appropriate tool for estimating IOP in rabbits, as long as adjustments are made for its slight tendency to underestimate actual IOP.

Cite This Article

APA
Mills EP, Liu CC, Emelogu U, Carter RT, Camacho-Luna P, Lewin AC. (2023). Validation of a novel rebound tonometer (Tono-Vera® Vet) in normal ex vivo rabbit eyes. Vet Ophthalmol, 26(6), 555-559. https://doi.org/10.1111/vop.13142

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 26
Issue: 6
Pages: 555-559

Researcher Affiliations

Mills, Erinn P
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Liu, Chin-Chi
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Emelogu, Ugochi
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Carter, Renee T
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Camacho-Luna, Pilar
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
Lewin, Andrew C
  • Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.

MeSH Terms

  • Rabbits
  • Animals
  • Dogs
  • Horses
  • Tonometry, Ocular / veterinary
  • Intraocular Pressure
  • Reproducibility of Results

References

This article includes 12 references
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Citations

This article has been cited 4 times.
  1. Wang C, Su Y, Shi F, Fu J. Comparison of three rebound tonometers in rabbits. Sci Rep 2025 Dec 29;15(1):44840.
    doi: 10.1038/s41598-025-28990-8pubmed: 41462550google scholar: lookup
  2. Lee J, Kim W, Shim J, Kim Y, Kang S, Yoo YK, Lee YH, Seo K. Validation of Recalibrated TONOVET Plus and TONOVET Pro in Canine Eyes Compared to Manometer and TONOVET. Vet Ophthalmol 2026 Jan;29(1):e70002.
    doi: 10.1111/vop.70002pubmed: 39935243google scholar: lookup
  3. Kapeller LE, Buckman PN, Wang S, Komáromy AM. Validation of the Reichert® Tono-Vera® Vet rebound tonometer in normal ex vivo canine eyes. Vet Ophthalmol 2024 May;27(3):290-293.
    doi: 10.1111/vop.13213pubmed: 38576120google scholar: lookup
  4. Kapeller LE, Cabble AG, Buckman PN, Harman CD, Jacobson AL, Lawrence FR, Komáromy AM. Validation of the eyeTelemed IOPvet indentation tonometer for use in dogs. Vet Ophthalmol 2024 Nov;27(6):492-500.
    doi: 10.1111/vop.13215pubmed: 38563215google scholar: lookup
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