title: Comparison of efficacy and duration of effect on corneal sensitivity among anesthetic agents following ocular administration in clinically normal horses.
abstract: OBJECTIVE
  To compare efficacy and duration of effect on corneal sensitivity of 0.5% proparacaine hydrochloride, 0.5% bupivacaine hydrochloride, 2% lidocaine hydrochloride, and 2% mepivacaine hydrochloride solutions following ocular administration in clinically normal horses.
  
  
  METHODS
  68 clinically normal horses.
  
  
  METHODS
  60 horses were assigned to receive 1 anesthetic agent in 1 eye. For each of another 8 horses, 1 eye was treated with each of the anesthetic agents in random order with a 1-week washout period between treatments. Corneal sensitivity was assessed via corneal touch threshold (CTT) measurements obtained with a Cochet-Bonnet aesthesiometer before and at 1 minute, at 5-minute intervals from 5 to 60 minutes, and at 10-minute intervals from 60 to 90 minutes after application of 0.2 mL of anesthetic agent. General linear mixed models were fitted to the CTT data from each of the 2 experimental groups to assess the effects of the anesthetic agents over time, accounting for repeated observations within individual horses.
  
  
  RESULTS
  Corneal sensitivity decreased immediately following topical application of each anesthetic agent; effects persisted for 35 minutes for proparacaine and mepivacaine treatments, 45 minutes for lidocaine treatment, and 60 minutes for bupivacaine treatment. Maximal CTT reduction was achieved following application of bupivacaine or proparacaine solution, whereas mepivacaine solution was least effective.
  
  
  CONCLUSIONS
  Ocular application of each evaluated anesthetic agent reduced corneal sensitivity in horses; although 0.5% proparacaine or 2% lidocaine solution appeared to induce adequate short-duration corneal anesthesia, use of 0.5% bupivacaine solution may be more appropriate for procedures requiring longer periods of corneal anesthesia.
authors: Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA. pucket@okstate.edu
authors: Jonathan D
authors: JD
authors: Pucket
authors: Rachel A
authors: RA
authors: Allbaugh
authors: Amy J
authors: AJ
authors: Rankin
authors: Zhining
authors: Z
authors: Ou
authors: Nora M
authors: NM
authors: Bello
mesh_terms: D060433:Administration, Ophthalmic / Q000662:veterinary; D000772:Anesthesia, Local / Q000379:methods / Q000592:standards / Q000662:veterinary*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage; D003315:Cornea / Q000187:drug effects*; D005260:Female; D006736:Horses / Q000502:physiology*; D008012:Lidocaine / Q000008:administration & dosage; D016014:Linear Models; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage; D011430:Propoxycaine / Q000008:administration & dosage; D011897:Random Allocation
chemical_list: D008012:Lidocaine; C005717:proxymetacaine; D008619:Mepivacaine; D011430:Propoxycaine; D002045:Bupivacaine