Duration of corneal anaesthesia following multiple doses and two concentrations of tetracaine hydrochloride eyedrops on the normal equine cornea.
Abstract: There is a clinical impression that tetracaine hydrochloride (THCl) eyedrops is a suitable topical anaesthetic in horses. Objective: To determine the duration of corneal anaesthesia following instillation of multiple doses and 2 concentrations of THCl in 10 healthy horses. Methods: The corneal touch threshold (CTT) was determined, in both eyes, before (basal CTT) and after application of one drop of 0.5% THCl, 2 drops at a 1 min interval of 0.5% THCl or one drop of 1% THCl. CTT was measured in mm every 5 min until complete recovery of the basal CTT. Treatments were separated by an interval of at least one week. Results: Corneal sensitivity was significantly reduced from baseline values for 30, 60 and 50 min after application of one drop of 0.5% THCl, 2 drops of 0.5% THCl and one drop of 1% THCl, respectively. Mean maximal anaesthetic effects, corresponding to a CTT of 0 mm, lasted 5.5, 16 and 15.25 min and maximal anaesthetic effect was present in 55, 90 and 80% of eyes, 5 min after application of one drop of 0.5% THCl, 2 drops of 0.5% THCl and one drop of 1% THCl, respectively. Conclusions: The application of a second drop or the use of more concentrated eyedrops significantly increases duration of both anaesthesia and maximal anaesthetic effect. Conclusions: Duration of corneal anaesthesia following tetracaine instillation was established enabling a better use when performing diagnostic and therapeutic procedures. Comparison of tetracaine with other ocular anaesthetics needs to be published in the future.
© 2010 EVJ Ltd.
Publication Date: 2010-12-15 PubMed ID: 21143636DOI: 10.1111/j.2042-3306.2010.00118.xGoogle Scholar: Lookup
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- Clinical Trial
- Journal Article
Summary
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This study aims to determine the duration of corneal anaesthesia in horses owing to the instillation of varying dosages and concentrations of tetracaine hydrochloride (THCl). The research discovers that applying more than one dosage or using more concentrated eyedrops significantly extends the duration of both anaesthesia and its maximum effect.
Objective and Methods
- The objective of this study was to ascertain the period of corneal numbness following the application of multiple doses and two concentrations (0.5% and 1%) of THCl in ten healthy horses.
- To achieve this, the corneal touch threshold (CTT), a measure of corneal sensitivity, was determined in both eyes before and after the application of the eyedrops.
- CTT was measured at intervals of 5 minutes until a full recovery of the basal CTT was observed.
- The entire processes were repeated after an interval of at least one week for each horse.
Results
- The study found that after the application of one drop of 0.5% THCl, corneal sensitivity was significantly reduced for approximately 30 minutes. This duration increased to 60 minutes when two drops of 0.5% THCl were used and reduced to 50 minutes when a drop of 1% THCl was used.
- The maximal anaesthetic effects, defined as a CTT of 0 mm, lasted for 5.5, 16 and 15.25 minutes respectively after the application of one drop of 0.5% THCl, two drops of 0.5% THCl, and one drop of 1% THCl.
- Around 55, 90, and 80% of the horses underwent maximal anaesthetic effects 5 minutes after the corresponding treatment methods.
Conclusions
- The researchers concluded that the application of a second drop or the use of a more concentrated THCl solution significantly lengthens the duration of both anaesthesia and its maximal effect.
- By understanding the duration of corneal anaesthesia following the instillation of THCl, better use can be achieved when performing diagnostic and therapeutic procedures on horses.
- The authors also noted that comparison between tetracaine and other ocular anaesthetics should be made in future publications, to further establish potential variations and implications in anaesthetic administration.
Cite This Article
APA
Monclin SJ, Farnir F, Grauwels M.
(2010).
Duration of corneal anaesthesia following multiple doses and two concentrations of tetracaine hydrochloride eyedrops on the normal equine cornea.
Equine Vet J, 43(1), 69-73.
https://doi.org/10.1111/j.2042-3306.2010.00118.x Publication
Researcher Affiliations
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Liège University, Liège, Belgium. smonclin@hotmail.com
MeSH Terms
- Administration, Topical
- Anesthesia, Local / veterinary
- Anesthetics, Local / administration & dosage
- Anesthetics, Local / pharmacology
- Animals
- Cornea / drug effects
- Drug Administration Schedule
- Female
- Horse Diseases / surgery
- Horses
- Male
- Ophthalmic Solutions
- Tetracaine / administration & dosage
- Tetracaine / pharmacology
Citations
This article has been cited 3 times.- Ziaei P, Resnick JL, Stella N, DiLeo MV. Novel Combined Lidocaine/Povidone Iodine Delivery System for Preintravitreal Injection. J Ocul Pharmacol Ther 2022 May;38(4):319-325.
- 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.
- Faghihi H, Rajaei SM, Ostadhasan H, Alagha HE. Effect of topical 0.5% tetracaine hydrochloride on intraocular pressure in ophthalmologically normal cats. J Feline Med Surg 2022 Feb;24(2):185-188.
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