Evaluation of healthy equine eyes by use of retinoscopy, keratometry, and ultrasonographic biometry.
Abstract: To assess natural variations in degree of refraction, corneal curvature, corneal astigmatism, corneal radius, and intraocular distance of healthy equine eyes. Methods: 159 horses with healthy eyes that were admitted to a veterinary teaching hospital for nonophthalmic surgeries. Methods: Eyes of horses were examined with a retinoscope prior to anesthesia and with a keratograph and A- and B-scan ultrasonographic biometers during surgery. In addition, manual caliper measurements of horizontal and vertical corneal radii were obtained. Results: Mean +/- SD degree of refraction in the horizontal meridian of eyes was -0.06 +/- 0.68 diopters (D). Vitreous body length and horse age correlated negatively with refraction values. The horizontal corneal radius (15.96 +/- 1.28 mm) was larger than the vertical corneal radius (15.02 +/- 1.09 mm). Accordingly, the vertical corneal curvature (21.56 +/- 1.68 D) was greater than the horizontal corneal curvature (22.89 +/- 1.65 D). Axial globe length (40.52 +/- 2.67 mm), anterior chamber depth (6.35 +/- 0.59 mm), lens thickness (12.30 +/- 0.83 mm), and vitreous body length (21.87 +/- 1.85 mm) were positively correlated with body weight, height, and age. Results of keratograph and caliper measurements correlated well for horizontal corneal diameter but poorly for vertical corneal diameter. Results of A- and B-scan ultrasonography differed by < or = 1 mm in 64% of measured eyes. Conclusions: Results of keratometry and ultrasonographic biometry varied widely. Additional research is needed to validate the keratograph used in our study for measurements in equine eyes.
Publication Date: 2010-06-02 PubMed ID: 20513184DOI: 10.2460/ajvr.71.6.677Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study aimed to evaluate healthy horse eyes with retinoscopy, keratometry, and ultrasonographic biometry, and found a broad range of measurement variations. Generated data need further validation.
Research Methods
- The research involved 159 horses with healthy eyes that were brought to a veterinary teaching hospital for surgeries not related to their eyes. The following examinations were conducted:
- Retinoscopy was performed on the horses’ eyes before anesthesia.
- During surgery, a keratograph (an instrument for measuring the curvature of the anterior surface of the cornea) and ultrasonographic biometers (A- and B-scan) were used for additional measurements.
- Manual caliper measurements were also taken to determine the horizontal and vertical radii of the cornea.
Research Findings
- The examination showed that the mean degree of refraction in the horizontal meridian of the eyes was -0.06 ± 0.68 diopters (D). There was a negative correlation observed between vitreous body length and age of horses with refraction values.
- The horizontal corneal radius was found to be larger than the vertical corneal radius. Similarly, the vertical corneal curvature was greater than the horizontal corneal curvature.
- Parameters such as axial globe length, lens thickness, vitreous body length, and depth of the anterior chamber were seen to be positively correlated with the body weight, height, and age of the horses.
- Between keratograph and caliper measurements, there was a good correlation for horizontal corneal diameter but poor for vertical corneal diameter.
- Results from A- and B-scan ultrasonography differed by ≤ 1 mm in 64% of the measured eyes.
Research Conclusions
- The study found a wide variation in keratometry and ultrasonographic biometry results. Hence, the authors suggest that additional research is needed to validate the keratograph used in the study for measurements in equine eyes.
Cite This Article
APA
Grinninger P, Skalicky M, Nell B.
(2010).
Evaluation of healthy equine eyes by use of retinoscopy, keratometry, and ultrasonographic biometry.
Am J Vet Res, 71(6), 677-681.
https://doi.org/10.2460/ajvr.71.6.677 Publication
Researcher Affiliations
- Department of Small Animals and Horses, Faculty of Veterinary Medicine, Vienna University, Vienna 1210, Austria. p.grinninger@uu.nl
MeSH Terms
- Age Factors
- Animals
- Biometry / methods
- Eye / anatomy & histology
- Eye / diagnostic imaging
- Female
- Horses / anatomy & histology
- Horses / physiology
- Male
- Multivariate Analysis
- Ocular Physiological Phenomena
- Retinoscopy / methods
- Retinoscopy / veterinary
- Sex Factors
- Ultrasonography
Citations
This article has been cited 9 times.- Knickelbein KE, Lassaline ME, Kim S, Scharbrough MS, Thomasy SM. Corneal thickness and anterior chamber depth of the normal adult horse as measured by ultrasound biomicroscopy.. Vet Ophthalmol 2022 May;25 Suppl 1(Suppl 1):17-24.
- Vercruysse E, Naranjo C, Sauvage A, Vandersmissen M, Grauwels M, Monclin S. Retinal detachment secondary to vitreoretinopathy in two closely related warmblood horses.. Open Vet J 2021 Oct-Dec;11(4):672-679.
- Abdelbaset-Ismail A, Aref M, Ezzeldein S, Eisa E, Gugjoo MB, Abdelaal A, Emam H, Al Syaad K, Ahmed AE, Alshati A, Abd El Raouf M. Ultrasound, Dacryocystorhinography and Morphological Examination of Normal Eye and Lacrimal Apparatus of the Donkey (Equus asinus).. Animals (Basel) 2022 Jan 6;12(2).
- Slenter IJM, Hermans H, Ensink JM, Willems DS, Veraa S, Grinwis GCM, Boevé MH. Clinical, ultrasonographic, and histopathologic findings in seven horses with Descemet's membrane detachment: A case series.. Vet Ophthalmol 2020 Jan;23(1):181-189.
- Meister U, Görig C, Murphy CJ, Haan H, Ohnesorge B, Boevé MH. Intraocular lens power calculation for the equine eye.. BMC Vet Res 2018 Apr 3;14(1):123.
- Fornazari GA, Montiani-Ferreira F, Filho IR, Somma AT, Moore B. The eye of the Barbary sheep or aoudad (Ammotragus lervia): reference values for selected ophthalmic diagnostic tests, morphologic and biometric observations.. Open Vet J 2016;6(2):102-13.
- Meister U, Ohnesorge B, Körner D, Boevé MH. Evaluation of ultrasound velocity in enucleated equine aqueous humor, lens and vitreous body.. BMC Vet Res 2014 Oct 14;10:250.
- Valentini S, Castagnetti C, Musella V, Spinella G. Assessment of intraocular measurements in neonatal foals and association with gender, laterality, and body weight: a clinical study.. PLoS One 2014;9(10):e109491.
- Gemensky-Metzler AJ, Wilkie DA, Weisbrode SE, Kuhn SE. The location of sites and effect of semiconductor diode trans-scleral cyclophotocoagulation on the buphthalmic equine globe.. Vet Ophthalmol 2014 Jul;17 Suppl 1(0 0):107-16.
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