Effect of head position on intraocular pressure in horses.
Abstract: To evaluate the effect of head position on intraocular pressure (IOP) in horses. Methods: 30 horses. Methods: Horses were sedated with detomidine HCl (0.01 mg/kg, IV). Auriculopalpebral nerve blocks were applied bilaterally with 2% lidocaine HCl. The corneas of both eyes were anesthetized with ophthalmic 0.5% proparacaine solution. Intraocular pressures were measured with an applanation tonometer with the head positioned below and above heart level. The mean of 3 readings was taken for each eye at each position for data analysis. The effect of head position on IOP was assessed and generalized estimating equations were used to adjust for the correlation from repeated measures of the same eye and intereye correlation from the same horse. Results: Of the 60 eyes, 52 (87%) had increased IOP when measured below the heart level. A significant difference (mean +/- SE, 8.20 +/- 1.01 mm Hg) was seen in the mean IOP when the head was above (17.5 +/- 0.8 mm Hg) or below (25.7 +/- 1.2 mm Hg) heart level. No significant effect of sex, age, or neck length on IOP change was found. Conclusions: Head position has a significant effect on the IOP of horses. Failure to maintain a consistent head position between IOP measurements could potentially prevent the meaningful interpretation of perceived aberrations or changes in IOP.
Publication Date: 2006-07-05 PubMed ID: 16817748DOI: 10.2460/ajvr.67.7.1232Google Scholar: Lookup
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- Clinical Trial
- Journal Article
- Research Support
- N.I.H.
- Extramural
Summary
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The research study investigates whether the position of a horse’s head influences its intraocular pressure (IOP). The results show a significant difference in IOP when the horse’s head is positioned below or above the heart level.
Research Methodology
- The study involved 30 horses who were sedated and anesthetized for the procedure.
- After sedation, nerve blocks were applied to both sides of the horse’s heads with lidocaine HCl.
- The corneas of both eyes were anaesthetized with an ophthalmic proparacaine solution to minimize discomfort during intraocular pressure measurements.
- Using an applanation tonometer, IOP readings were taken from the horse’s eyes in two positions – with the head above heart level and with the head below heart level.
- Three readings were taken for every eye in each position and their mean values were considered for analysis.
Results
- Out of 60 eyes from 30 horses, 52 eyes (87%) showed an increase in IOP when measured below the heart level.
- There was a significant increase (mean +/- SE, 8.20 +/- 1.01 mm Hg) in the mean IOP when the head was below (25.7 +/- 1.2 mm Hg) heart level as compared to above (17.5 +/- 0.8 mm Hg) heart level.
- No significant effect of the horse’s sex, age, or neck length on the change in IOP was found.
Conclusions
- This research concludes that the head position considerably affects IOP in horses. Therefore, head position is a crucial factor to consider during IOP measurements to maintain consistency.
- The failure to maintain a consistent head position might lead to inaccuracies in the interpretation of perceived changes or aberrations in IOP.
Cite This Article
APA
Komáromy AM, Garg CD, Ying GS, Liu C.
(2006).
Effect of head position on intraocular pressure in horses.
Am J Vet Res, 67(7), 1232-1235.
https://doi.org/10.2460/ajvr.67.7.1232 Publication
Researcher Affiliations
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, 19104, USA.
MeSH Terms
- Aging
- Animals
- Female
- Head / physiology
- Horses / physiology
- Intraocular Pressure / physiology
- Male
- Neck
- Ocular Physiological Phenomena
- Posture / physiology
- Tonometry, Ocular
Grant Funding
- K12 EY015398 / NEI NIH HHS
- P30 EY001583 / NEI NIH HHS
Citations
This article has been cited 9 times.- Fang R, Zhang P, Zhang T, Yan Z, Kim D, Sun E, Kuranov R, Kweon J, Huang AS, Zhang HF. Robotic Optical Coherence Tomography With Expanded Three-Dimensional Field-of-View Using Point-Cloud-Based Volumetric Montaging. IEEE Trans Med Imaging 2025 Nov;44(11):4639-4651.
- Allen R, Goodhead AD. A survey of ocular pathology in Warmblood horses in South Africa. Equine Vet J 2025 Jul;57(4):889-897.
- 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.
- 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.
- Mustikka MP, Pietilä EM, Mykkänen AK, Grönthal TSC. Comparison of two rebound tonometers in healthy horses. Vet Ophthalmol 2020 Sep;23(5):892-898.
- Rizk A, Nocera I, Briganti A, Abouelnasr K, El-Khodery S, Tagawa M, Bonelli F. Dose-dependent effect of romifidine on intraocular pressure in clinically healthy buffalo (Bubalus bubalis). Heliyon 2019 Dec;5(12):e02930.
- Kurt B, Çağatay HH, Aksoy Ö. The effect of body position on intraocular pressure in calves. J S Afr Vet Assoc 2018 Aug 20;89(0):e1-e3.
- Selk Ghaffari M, Arman Gherekhloo A. Effect of body position on intraocular pressure in clinically normal cats. J Feline Med Surg 2018 Aug;20(8):749-751.
- Delgado C, Mans C, McLellan GJ, Bentley E, Sladky KK, Miller PE. Evaluation of rebound tonometry in red-eared slider turtles (Trachemys scripta elegans). Vet Ophthalmol 2014 Jul;17(4):261-7.
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