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Evaluation of duration of corneal anesthesia induced with ophthalmic 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in clinically normal horses.
Abstract: To measure duration of corneal anesthesia and time and degree of maximal anesthetic effect of 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in horses. Methods: 10 clinically normal adult horses. Methods: Baseline corneal touch threshold (CTT) was measured in millimeters for 1 randomly selected eye of each horse by use of the aesthesiometer by applying the filament to the cornea at maximum length (60 mm) and decreasing in 5-mm increments until a consistent blink response was elicited. Following baseline CTT measurement, 0.2 mL of 0.5% proparacaine hydrochloride was instilled in the selected eye. The CTT was measured within 1 minute following proparacaine administration and every 5 minutes thereafter for 60 minutes. A mixed-model ANOVA with tested eye varying between subjects and measurement time varying within subject was used to test for main effects and any interaction between these factors. A contrast between means of baseline and each subsequent CTT identified the duration of corneal anesthesia as the time at which there was no difference from baseline. Maximal anesthetic effect occurred at the time with the lowest mean CTT. Results: Duration of corneal anesthesia achieved by use of proparacaine was 25 minutes, and maximal anesthetic effect occurred within 5 minutes, although CTT never went to 0 in any horse at any time. Conclusions: Duration of corneal anesthesia in horses was shorter than in dogs, and degree of maximal effect was less than in cats and dogs, most likely because of increased sensitivity of the equine cornea, compared with corneal sensitivity in those species.
Publication Date: 2008-12-03 PubMed ID: 19046014DOI: 10.2460/ajvr.69.12.1655Google 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.
- Journal Article
Summary
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The research article is about a study undertaken to measure the duration and intensity of corneal anesthesia effect induced by 0.5% proparacaine hydrochloride in horses using a Cochet-Bonnet aesthesiometer.
Objective and Methodology
- The purpose of this research was to assess the length and magnitude of corneal anesthesia caused by 0.5% proparacaine hydrochloride in horses.
- The subjects for the study were ten healthy adult horses. The corneal touch threshold (CTT) for one eye of each horse was measured as a baseline.
- An aesthesiometer, a device that measures sensitivity of the skin or cornea, was used. The tool uses a filament that is applied to the cornea at maximum length (60mm), decreased by 5mm increments until a consistent blink response is produced.
- Following the initial measurement, 0.2 mL of 0.5% proparacaine hydrochloride was administered in the selected eye, and the CTT was measured within one minute and every 5 minutes after for one hour.
Statistical Analysis
- A mixed-model ANOVA (Analysis of Variance) method was employed, this tool is used in statistics to test for a difference in means. The tested eye varied among subjects while the measuring time varied per subject.
- To identify the duration of corneal anesthesia, the researchers compared the means of the baseline and each subsequent CTT. The period was considered to have ended when there was no significant difference from the baseline measurement.
- The maximal anesthetic effect was determined by the time with the lowest mean CTT.
Results and Conclusions
- The results indicated that the maximum anesthetic effect was seen within 5 minutes and the period of corneal anesthesia induced by proparacaine lasted for 25 minutes. However, it’s noteworthy that the CTT never decreased to zero in any horse at any point.
- w>ith respect to their findings, the researchers concluded that the duration of corneal anesthesia in horses was shorter than in dogs, and the degree of maximal effect was lower as compared to cats and dogs. This contrast was attributed to the increased sensitivity of the horse’s cornea, compared to the dogs’ and cats’ corneal sensitivity.
Cite This Article
APA
Kalf KL, Utter ME, Wotman KL.
(2008).
Evaluation of duration of corneal anesthesia induced with ophthalmic 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in clinically normal horses.
Am J Vet Res, 69(12), 1655-1658.
https://doi.org/10.2460/ajvr.69.12.1655 Publication
Researcher Affiliations
- New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA.
MeSH Terms
- Administration, Topical
- Anesthesia, Local / instrumentation
- Anesthesia, Local / veterinary
- Anesthetics, Local / administration & dosage
- Anesthetics, Local / pharmacology
- Animals
- Cornea / drug effects
- Horses
- Ophthalmic Solutions
- Propoxycaine / administration & dosage
- Propoxycaine / pharmacology
Citations
This article has been cited 5 times.- Kyei S, Abaka Dadzie NY, Zaabaar E, Asamoah Dwomoh KA, Asiedu K. Age and Sex Variation in the Duration of Action and Corneal Touch Threshold (CTT) following Instillation of 0.5% Topical Ophthalmic Proparacaine and Tetracaine Hydrochlorides. J Ophthalmol 2021;2021:8661098.
- Sarchahi AA, Eskandari M. Effect of four local anesthetics (tetracaine, proparacaine, lidocaine, and bupivacaine) on intraocular pressure in dogs. Int Ophthalmol 2019 Jul;39(7):1467-1474.
- Telle MR, Chen N, Shinsako D, Kiland JA, Oikawa K, Møller Trane R, McLellan GJ. Relationship between corneal sensitivity, corneal thickness, corneal diameter, and intraocular pressure in normal cats and cats with congenital glaucoma. Vet Ophthalmol 2019 Jan;22(1):4-12.
- Trbolova A, Ghaffari MS. Results of the Schirmer tear test performed with open and closed eyes in clinically normal horses. Acta Vet Scand 2017 May 31;59(1):35.
- Little E, Yvorchuk-St Jean K, Little W, Sithole F, St Jean G. Degree of corneal anesthesia after topical application of 0.4% oxybuprocaine ophthalmic solution in normal equids. Can J Vet Res 2016 Oct;80(4):329-334.
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