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Dexmedetomidine Prolongs the Duration of Ropivacaine Corneal Anesthesia After Subconjunctival Injection in Healthy Horses.
Abstract: To determine whether dexmedetomidine prolongs corneal anesthesia following subconjunctival ropivacaine injection in healthy equine eyes. Methods: Ten horses with normal ophthalmic exams were enrolled in a randomized, blinded, crossover experiment with a minimum 4-week washout between treatments. Baseline corneal touch thresholds (CTT, cm) were measured via esthesiometry and a subconjunctival injection was performed in the treatment eye with ropivacaine (R, 0.3 mL 0.5%) or dexmedetomidine-ropivacaine (DR, 0.1 mL 0.5 mg/mL + 0.2 mL 0.5%) and saline (control, 0.3 mL) in the contralateral eye. CTT was measured every 10 min up to 120 min, every 30 min up to 360 min, and every 60 min thereafter until return to baseline. Ambient humidity was concurrently recorded. Subconjunctival hemorrhage was scored 0, 2, and 7 days after injection. CTT values were converted to corneal pressure tolerance (CPT, g/mm) using humidity-adjusted exponential regression. Data were compared between treatments using mixed model analysis (significance p < 0.05). Results: Mean ± standard deviation total anesthesia time was significantly longer with DR (196 ± 121 vs. 103 ± 47 min R, p = 0.02). Evidence of significant differences between treatments was not seen for minimum CTT, duration of minimum CTT, maximal CPT, or hemorrhage scores. However, time to minimum CTT was longer for DR (32 ± 12 vs. 16 ± 10 min R, p < 0.001). Subconjunctival hemorrhage resolved within 7 days of injection. Conclusions: Dexmedetomidine prolongs corneal anesthesia from subconjunctival ropivacaine in horses but delays the onset. Further studies are needed to assess efficacy in diseased eyes.
© 2026 The Author(s). Veterinary Ophthalmology published by Wiley Periodicals LLC on behalf of American College of Veterinary Ophthalmologists.
Publication Date: 2025-12-01 PubMed ID: 41324135PubMed Central: PMC12963526DOI: 10.1111/vop.70124Google 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
- Randomized Controlled Trial
- Veterinary
- Clinical Trial
- Veterinary
Cite This Article
APA
Lee S, Hector RC, Hess AM, Wotman KL.
(2025).
Dexmedetomidine Prolongs the Duration of Ropivacaine Corneal Anesthesia After Subconjunctival Injection in Healthy Horses.
Vet Ophthalmol, 29(2), e70124.
https://doi.org/10.1111/vop.70124 Publication
Researcher Affiliations
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
- Department of Statistics, College of Natural Sciences, Colorado State University, Fort Collins, Colorado, USA.
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
MeSH Terms
- Animals
- Horses
- Ropivacaine / administration & dosage
- Ropivacaine / pharmacology
- Anesthetics, Local / administration & dosage
- Anesthetics, Local / pharmacology
- Cornea / drug effects
- Dexmedetomidine / administration & dosage
- Dexmedetomidine / pharmacology
- Cross-Over Studies
- Female
- Male
- Injections, Intraocular / veterinary
- Anesthesia, Local / veterinary
- Conjunctiva
Conflict of Interest Statement
The authors have not used AI to generate any part of the manuscript. The authors declare no conflicts of interest.
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Citations
This article has been cited 1 times.- Wang C, Su Y, Shi F, Fu J. Comparison of three rebound tonometers in rabbits. Sci Rep 2025 Dec 29;15(1):44840.
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