FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Veterinary ophthalmology2020; 23(5); 892-898; doi: 10.1111/vop.12819

Comparison of two rebound tonometers in healthy horses.

Abstract: To obtain a reference range for evaluation of intraocular pressure (IOP) in horses using Tonovet Plus , to compare the IOP readings obtained with Tonovet and Tonovet Plus , and to evaluate the repeatability of readings. Unassigned: Intraocular pressure of 30 client-owned horses (60 eyes) with no signs of illness or ocular disease was evaluated using Tonovet and Tonovet Plus rebound tonometers. Horses' mean age was 10.7 (range 6-17) years. Triplicate measurements were performed without using sedatives or local anesthetics, with minimal restraint. Results: Calculated reference intervals (the CLSI robust method) were 14.4-27.2 mmHg for Tonovet and 16.0-26.1 mmHg for Tonovet Plus . Mean values (± standard deviation, SD [± coefficient of variation, CV]) obtained with Tonovet Plus (21.6 ± 2.45 mmHg [11.3%]) were on average 0.6 mmHg higher than with Tonovet (21.0 ± 3.14 mmHg [15.0%]), and a negligible statistical difference between the devices was found using the paired sample t test (P = .049). The correlation coefficient for the averaged triplicate measurements was 0.73. The average CV was 4.6% and 4.4% for Tonovet and Tonovet Plus , respectively. Conclusions: The repeatability of measurements was very good with both devices. The readings between the two devices differed statistically significantly, but the correlation was considered good and the variation was numerically small, and thus, the difference was considered clinically irrelevant. When monitoring disease process or treatment response in an individual patient, repeated readings are best performed using a similar device to avoid false interpretation of results.
© 2020 The Authors. Veterinary Ophthalmology published by Wiley Periodicals LLC on behalf of American College of Veterinary Ophthalmologists.
Get Full Text
Publication Date: 2020-09-04 PubMed ID: 32888242PubMed Central: PMC7540552DOI: 10.1111/vop.12819Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Comparative Study
  • 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 research study assessed the reliability and comparison of intraocular pressure (IOP) measurements taken from horses using two different tonometers, Tonovet and Tonovet Plus. The findings suggest that the measurements from both devices were generally consistent, albeit statistically significant, but the difference was considered clinically insignificant for evaluating eye health in horses.

Methodology

  • The study involved 30 horses, ranging in age from 6-17 years, that were in good health and showed no signs of ocular disease.
  • Both eyes of each horse were tested using both Tonovet and Tonovet Plus rebound tonometers, making a total of 60 eyes.
  • To eliminate possible variables, no sedatives or local anesthetics were used during the procedure, and minimal restraint of the horses was employed.
  • Each device took three measurements per eye, and these values were averaged to achieve a final result.

Results

  • The reference intervals calculated by the CLSI robust method were 14.4-27.2 mmHg for the Tonovet and 16.0-26.1 mmHg for Tonovet Plus.
  • The mean IOP recorded by Tonovet Plus was slightly higher (by 0.6 mmHg) than that recorded by Tonovet, an insignificant difference statistically.
  • The correlation coefficient for averaged triplicate measurements was 0.73, demonstrating a strong correlation between the measurements from the two devices.
  • The average coefficient of variation was 4.6% for Tonovet and 4.4% for Tonovet Plus, affirming the repeatability of measurements using both devices was very good.

Conclusion

  • Despite statistically significant differences, the correlation between readings of the two devices was good, and the variation was numerically small, making the difference clinically irrelevant.
  • For consistent results, it is recommended to use the same device when taking repeated IOP readings. This is to avoid false interpretation of results while monitoring any disease process or response to treatment in a patient.

Cite This Article

APA
Mustikka MP, Pietilä EM, Mykkänen AK, Grönthal TSC. (2020). Comparison of two rebound tonometers in healthy horses. Vet Ophthalmol, 23(5), 892-898. https://doi.org/10.1111/vop.12819

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 23
Issue: 5
Pages: 892-898

Researcher Affiliations

Mustikka, Minna P
  • Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland.
Pietilä, Elina M
  • Veterinary Clinic Apex, Helsinki, Finland.
Mykkänen, Anna K
  • Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland.
Grönthal, Thomas S C
  • Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland.

MeSH Terms

  • Animals
  • Eye
  • Female
  • Horses / physiology
  • Intraocular Pressure
  • Male
  • Reference Values
  • Tonometry, Ocular / instrumentation
  • Tonometry, Ocular / veterinary

Conflict of Interest Statement

The authors thank Icare Finland Oy for providing the Tonovet Plus device and the probes needed to perform this study. Icare Finland did not influence study design or the collection, analysis, or interpretation of data. None of the authors has a financial relationship with Icare Finland Oy that could influence or bias the study content.

References

This article includes 39 references
  1. Stoppini R, Gilger BC. Equine ocular examination basic techniques. In: Gilger BC, ed. Equine Ophthalmology, 3rd edn. Ames, IA: John Wiley & Sons; 2017:1‐39.
  2. Featherstone HJ, Heinrich CL. Ophthalmic examination and diagnostics. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology, 5th edn. Ames, IA: John Wiley & Sons; 2013:533‐702.
  3. Michau TM. Equine Glaucoma.. Vet Clin North Am Equine Pract 2017 Dec;33(3):519-540.
    pubmed: 29103560doi: 10.1016/j.cveq.2017.07.005google scholar: lookup
  4. Gilger BC. Equine ophthalmology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology, 5th edn. Ames, IA: John Wiley & Sons; 2013:1561‐1609.
  5. Wilkie DA, Gemensky‐Metzler AJ, Lassaline M, Brooks DE. Glaucoma. In: Gilger BC, ed. Equine Ophthalmology, 3rd edn. Ames, IA: John Wiley & Sons; 2017:453‐468.
  6. Knollinger AM, La Croix NC, Barrett PM, Miller PE. Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses.. J Am Vet Med Assoc 2005 Jul 15;227(2):244-8.
    pubmed: 16047660doi: 10.2460/javma.2005.227.244google scholar: lookup
  7. Miller PE, Pickett JP, Majors LJ. Evaluation of two applanation tonometers in horses.. Am J Vet Res 1990 Jun;51(6):935-7.
    pubmed: 2368953
  8. Dziezyc J, Millichamp NJ, Smith WB. Comparison of applanation tonometers in dogs and horses.. J Am Vet Med Assoc 1992 Aug 1;201(3):430-3.
    pubmed: 1506245
  9. Holve DL. Effect of sedation with detomidine on intraocular pressure with and without topical anesthesia in clinically normal horses.. J Am Vet Med Assoc 2012 Feb 1;240(3):308-11.
    pubmed: 22256847doi: 10.2460/javma.240.3.308google scholar: lookup
  10. van der Woerdt A, Gilger BC, Wilkie DA, Strauch SM. Effect of auriculopalpebral nerve block and intravenous administration of xylazine on intraocular pressure and corneal thickness in horses.. Am J Vet Res 1995 Feb;56(2):155-8.
    pubmed: 7717576
  11. Abraham LM, Epasinghe NC, Selva D, Casson R. Comparison of the ICare rebound tonometer with the Goldmann applanation tonometer by experienced and inexperienced tonometrists.. Eye (Lond) 2008 Apr;22(4):503-6.
    pubmed: 17159973doi: 10.1038/sj.eye.6702669google scholar: lookup
  12. McLellan GJ, Kemmerling JP, Kiland JA. Validation of the TonoVet® rebound tonometer in normal and glaucomatous cats.. Vet Ophthalmol 2013 Mar;16(2):111-8.
    pmc: PMC3443498pubmed: 22672669doi: 10.1111/j.1463-5224.2012.01038.xgoogle scholar: lookup
  13. Görig C, Coenen RT, Stades FC, Djajadiningrat-Laanen SC, Boevé MH. Comparison of the use of new handheld tonometers and established applanation tonometers in dogs.. Am J Vet Res 2006 Jan;67(1):134-44.
    pubmed: 16426223doi: 10.2460/ajvr.67.1.134google scholar: lookup
  14. Lewin AC, Liu CC, Camacho-Luna P, Alling C, Carter RT. Inter-user and intra-user variation of two tonometers in horses.. Equine Vet J 2020 Jul;52(4):572-576.
    pubmed: 31721273doi: 10.1111/evj.13208google scholar: lookup
  15. Priehs DR, Gum GG, Whitley RD, Moore LE. Evaluation of three applanation tonometers in dogs.. Am J Vet Res 1990 Oct;51(10):1547-50.
    pubmed: 2240775
  16. Gloe S, Rothering A, Kiland JA, McLellan GJ. Validation of the Icare(®) TONOVET plus rebound tonometer in normal rabbit eyes.. Exp Eye Res 2019 Aug;185:107698.
    pmc: PMC6698397pubmed: 31201805doi: 10.1016/j.exer.2019.107698google scholar: lookup
  17. Ben-Shlomo G, Muirhead SF. Estimation of intraocular pressure in normal canine eyes utilizing the newly introduced TonoVet Plus and TonoPen Avia, and their comparison to the established TonoVet.. Vet Ophthalmol 2021 Mar;24 Suppl 1:171-174.
    doi: 10.1111/vop.12747pubmed: 32154987google scholar: lookup
  18. Komáromy AM, Garg CD, Ying GS, Liu C. Effect of head position on intraocular pressure in horses.. Am J Vet Res 2006 Jul;67(7):1232-5.
    pubmed: 16817748doi: 10.2460/ajvr.67.7.1232google scholar: lookup
  19. Klein HE, Krohne SG, Moore GE, Mohamed AS, Stiles J. Effect of eyelid manipulation and manual jugular compression on intraocular pressure measurement in dogs.. J Am Vet Med Assoc 2011 May 15;238(10):1292-5.
    pubmed: 21568774doi: 10.2460/javma.238.10.1292google scholar: lookup
  20. Morris CA, Crowston JG, Lindsey JD, Danias J, Weinreb RN. Comparison of invasive and non-invasive tonometry in the mouse.. Exp Eye Res 2006 Jun;82(6):1094-9.
    pubmed: 16466714doi: 10.1016/j.exer.2005.12.001google scholar: lookup
  21. Andrade SF, Palozzi RJ, Giuffrida R, de Campos RJ, Santos Gde C, Fukui RM. Comparison of intraocular pressure measurements between the Tono-Pen XL® and Perkins® applanation tonometers in dogs and cats.. Vet Ophthalmol 2012 Mar;15 Suppl 1:14-20.
    pubmed: 22050624doi: 10.1111/j.1463-5224.2011.00926.xgoogle scholar: lookup
  22. Hibbs CD, Barrett PM, Dees DD. Intraocular pressure reference intervals in eyes of clinically normal miniature donkeys (Equus africanus asinus).. Vet Ophthalmol 2019 Jan;22(1):24-30.
    pubmed: 29517162doi: 10.1111/vop.12561google scholar: lookup
  23. von Spiessen L, Karck J, Rohn K, Meyer-Lindenberg A. Clinical comparison of the TonoVet(®) rebound tonometer and the Tono-Pen Vet(®) applanation tonometer in dogs and cats with ocular disease: glaucoma or corneal pathology.. Vet Ophthalmol 2015 Jan;18(1):20-7.
    pubmed: 24131625doi: 10.1111/vop.12101google scholar: lookup
  24. Tofflemire KL, Wang C, Jens JK, Ellinwood NM, Whitley RD, Ben-Shlomo G. Evaluation of three hand-held tonometers in normal canine eyes.. Vet J 2017 Jun;224:7-10.
    pubmed: 28697879doi: 10.1016/j.tvjl.2017.04.003google scholar: lookup
  25. Allingham RR, Damji KF, Freedman SF, Rhee DJ, Shields MB. Intraocular pressure and tonometry. In: Allingham RR, Shields MB, eds. Shields Textbook of Glaucoma, 6th edn. Philadelphia, PA: Wolters Kluwer/Lippincott Williams & Wilkins Health cop; 2011:24‐40.
  26. Dosunmu EO, Marcus I, Tung I, Thiamthat W, Freedman SF. The effect of repeated measurements and the use of topical anesthetic on rebound tonometry values in children.. J AAPOS 2014 Dec;18(6):619-21.
    pubmed: 25448141doi: 10.1016/j.jaapos.2014.07.167google scholar: lookup
  27. Labelle AL, Hamor RE, Townsend WM, Mitchell MA, Zarfoss MK, Breaux CB, Thomasy SM, Hall T. Ophthalmic lesions in neonatal foals evaluated for nonophthalmic disease at referral hospitals.. J Am Vet Med Assoc 2011 Aug 15;239(4):486-92.
    pubmed: 21838586doi: 10.2460/javma.239.4.486google scholar: lookup
  28. Leiva M, Pena T, Monreal L. Ocular findings in healthy newborn foals according to age. Equine Vet Educ 2010;23:40‐45.
  29. Rosentreter A, Athanasopoulos A, Schild AM, Lappas A, Cursiefen C, Dietlein TS. Rebound, applanation, and dynamic contour tonometry in pathologic corneas.. Cornea 2013 Mar;32(3):313-8.
    pubmed: 22673854doi: 10.1097/ico.0b013e318254a3fbgoogle scholar: lookup
  30. de Oliveira JK, Montiani-Ferreira F, Williams DL. The influence of the tonometer position on canine intraocular pressure measurements using the Tonovet(®) rebound tonometer.. Open Vet J 2018;8(1):68-76.
    pmc: PMC5918127pubmed: 29721435doi: 10.4314/ovj.v8i1.12google scholar: lookup
  31. Bertolucci C, Giudice E, Fazio F, Piccione G. Circadian intraocular pressure rhythms in athletic horses under different lighting regime.. Chronobiol Int 2009 Feb;26(2):348-58.
    pubmed: 19212846doi: 10.1080/07420520902751035google scholar: lookup
  32. Trim CM, Colbern GT, Martin CL. Effect of xylazine and ketamine on intraocular pressure in horses.. Vet Rec 1985 Oct 26;117(17):442-3.
    pubmed: 4071935doi: 10.1136/vr.117.17.442google scholar: lookup
  33. Diehl K, Bowden AC. Effect of auriculopalpebral nerve block on equine intraocular pressure measured by rebound tonometry (TonoVet(®) ).. Vet Ophthalmol 2020 Mar;23(2):368-373.
    pubmed: 31908137doi: 10.1111/vop.12735google scholar: lookup
  34. Wilkie DA, Gilger BC. Equine glaucoma.. Vet Clin North Am Equine Pract 2004 Aug;20(2):381-91, vii.
    pubmed: 15271429doi: 10.1016/j.cveq.2004.04.002google scholar: lookup
  35. McClure JR Jr, Gelatt KN, Gum GG, Manning JP. The effect of parenteral acepromazine and xylazine on intraocular pressure in the horse.. Vet Med Small Anim Clin 1976 Dec;71(12):1727-30.
    pubmed: 1051773
  36. Stine JM, Michau TM, Williams MK, Kuebelbeck KL, Stengard ME. The effects of intravenous romifidine on intraocular pressure in clinically normal horses and horses with incidental ophthalmic findings.. Vet Ophthalmol 2014 Jul;17 Suppl 1:134-9.
    pubmed: 24787635doi: 10.1111/vop.12172google scholar: lookup
  37. Marzok MA, El-Khodery SA, Oheida AH. Effect of intravenous administration of romifidine on intraocular pressure in clinically normal horses.. Vet Ophthalmol 2014 Jul;17 Suppl 1:149-53.
    pubmed: 24836894doi: 10.1111/vop.12181google scholar: lookup
  38. Von Zup M, Lassaline M, Kass PH, Miller PE, Thomasy SM. Effects of 0.2% brimonidine and 0.2% brimonidine-0.5% timolol on intraocular pressure and pupil size in normal equine eyes.. Equine Vet J 2017 Nov;49(6):810-814.
    pmc: PMC5640458pubmed: 28470857doi: 10.1111/evj.12695google scholar: lookup
  39. Peche N, Eule JC. Intraocular pressure measurements in cattle, sheep, and goats with 2 different types of tonometers.. Can J Vet Res 2018 Jul;82(3):208-215.
    pmc: PMC6040018pubmed: 30026646

Citations

This article has been cited 5 times.
  1. Stas EKL, Hermans H, Slenter IJM, Veraa S, Ensink JM. Noninvasive diode laser-an effective and safe treatment of iris cysts in 46 eyes of 35 horses. Equine Vet J 2023 Mar;55(2):205-213.
    doi: 10.1111/evj.13590pubmed: 35575001google 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. Preston JF, Mustikka MP, Priestnall SL, Dunkel B, Fischer MC. Clinical features and outcomes of horses presenting with presumed equine immune mediated keratitis to two veterinary hospitals in the United Kingdom and Finland: 94 cases (2009-2021). Equine Vet J 2025 May;57(3):598-610.
    doi: 10.1111/evj.14213pubmed: 39183684google scholar: lookup
  4. Kovalcuka L, Mālniece A, Vanaga J. Comparison of Tonovet® and Tonovet plus® tonometers for measuring intraocular pressure in dogs, cats, horses, cattle, and sheep. Vet World 2024 Feb;17(2):384-388.
    doi: 10.14202/vetworld.2024.384-388pubmed: 38595645google scholar: lookup
  5. Cinar H, Yanmaz LE, Buyukkaraca N, Kaya Z, Kosuncu M. Comparing the effects of intraocular pressure and tear production measurements in horses in two different environments: Horse stable and medical barn. Equine Vet J 2025 Jan;57(1):271-276.
    doi: 10.1111/evj.14067pubmed: 38268120google scholar: lookup
Subscribe to our newsletter
Join 99,911 horse owners like you who receive our email updates on horse health and nutrition.