J Vet Sci.  2011 Jun;12(2):171-176. 10.4142/jvs.2011.12.2.171.

Evaluation of the Perkins handheld applanation tonometer in horses and cattle

• Andrade SF
• Kupper DS
• de Pinho L
• Franco EC
• Prataviera MVFF
• Duarte RR
• Junqueira

• KMID: 1106560
• DOI: http://doi.org/10.4142/jvs.2011.12.2.171

Abstract

The objective of this study was to evaluate and validate the accuracy of the Perkins handheld applanation tonometer for measuring intraocular pressure (IOP) in horses and cattle. Both eyes of 10 adult horses and cattle were evaluated in a postmortem study. The eyes from 10 clinically normal adult horses and cattle were also examined after bilateral auriculopalpebral nerve block and topical anesthesia for an in vivo study. IOP was measured postmortem using direct manometry (measured with an aneroid manometer) and tonometry (measured with a Perkins handheld applanation tonometer). The correlation coefficients (r2 ) for the data from the postmortem manometry and Perkins tonometer study were 0.866 for horses and 0.864 for cattle. In the in vivo study, IOP in horses was 25.1 +/- 2.9 mmHg (range 19.0~30.0 mmHg) as measured by manometry and 23.4 +/- 3.2 mmHg (range 18.6~28.4 mmHg) according to tonometry. In cattle, IOP was found to be 19.7 +/- 1.2 mmHg (range 18.0~22.0 mmHg) by manometry and 18.8 +/- 1.7 mmHg (range 15.9~20.8 mmHg) by tonometry. There was a strong correlation between the IOP values obtained by direct ocular manometry and the tonometer in both horses and cattle. Our results demonstrate that the Perkins handheld tonometer could be an additional tool for accurately measuring IOP in equine and bovine eyes.

Keyword

applanation tonometry; bovine; equine; intraocular pressure; ocular manometry

MeSH Terms

Animals
Cattle/*physiology
Eye/*physiopathology
Horses/*physiology
Intraocular Pressure/*physiology
Linear Models
Manometry/instrumentation/veterinary
Tonometry, Ocular/instrumentation/*veterinary

Figure

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  Fig. 1 Postmortem study in an eye remaining within the orbits in the head of an adult horse. (A) A 23-gauge scalp vein needle connected via a polyethylene tube to a three-way stopcock The stopcock was also connected to a 10 mL reservoir of a 0.9% physiological saline solution with the stopcock in an open mode and to an aneroid manometer. (B) Cannulation of the anterior chamber using a 23-gauge scalp vein needle near the limbus. Cyanoacrylate glue was applied around the needle to prevent leakage of the aqueous humor.

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  Fig. 2 In vivo study in horses. (A) Auriculopalpebral nerve block anesthesia with 10 mL of lidocaine 2%. (B) Topical anesthesia with two eye drops of 1% tetracaine. (C) Fluorescein eye drop. (D) Perkins tonometer IOP reading. (E) Cannulation of the anterior chamber. (F) Aneroid manometer IOP reading of 20 mmHg.

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  Fig. 3 In vivo study in cattle. (A) Auriculopalpebral nerve block localization. (B) Local anesthesia with 10 mL of 2% lidocaine. (C) Topical anesthesia with two eye drops of 1% tetracaine. (D) Fluorescein eye drop. (E) Perkins tonometer IOP reading. (F) Cannulation using a 23-gauge scalp vein needle to determine the IOP by aneroid manometry. (G) Application of cyanoacrylate glue. (H) Cyanoacrylate glue covering the site of cannulation. (I) Diclofenac sodium eye drop.

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  Fig. 4 Regression lines of IOP values from the Perkins applanation tonometer vs. ones from direct postmortem ocular manometry for the eyes of (A) horses (n = 10) and (B) cattle (n = 10).

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