title: Comparison of peribulbar and retrobulbar regional anesthesia with bupivacaine in cats.
abstract: OBJECTIVE
  To compare effectiveness and complications associated with peribulbar and retrobulbar anesthesia with bupivacaine in cats.
  
  
  METHODS
  6 healthy adult cats.
  
  
  METHODS
  Cats were sedated with dexmedetomidine and received a peribulbar injection of 0.5% bupivacaine (1.5 mL), iopamidol (0.5 mL), and saline (0.9% NaCl) solution (1 mL) or retrobulbar injection of 0.5% bupivacaine (0.75 mL) and iopamidol (0.25 mL) in a crossover study with ≥ 2 weeks between treatments. The contralateral eye was the control. Injectate distribution was evaluated with CT. After atipamezole administration, periocular and corneal sensations, intraocular pressure (IOP), and ocular reflexes and appearance were evaluated for 24 hours.
  
  
  RESULTS
  All peribulbar and 3 of 6 retrobulbar injections resulted in CT evidence of intraconal injectate. Corneal sensation and periocular skin sensation were absent or significantly reduced relative to that for control eyes for 3 hours after peribulbar injection. Mean ± SD IOP immediately after injection was significantly higher for eyes with peribulbar injections (33 ± 12 mm Hg) than for control eyes or eyes with retrobulbar injections (both 14 ± 4 mm Hg) but 10 minutes later decreased to 18 ± 3 mm Hg. Exophthalmos, chemosis, and ptosis were evident in most injected eyes, and irritation was evident in 3 of 6 peribulbar-injected and 1 of 6 retrobulbar-injected eyes. All conditions resolved within 14 hours.
  
  
  CONCLUSIONS
  Peribulbar injection resulted in intraconal deposition of bupivicaine in a higher percentage of cats than did retrobulbar injection and induced notable anesthesia relative to that for the control eye; however, IOP increased temporarily.
authors.affiliation: Departments of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.
authors.forename: Yael
authors.initials: Y
authors.lastname: Shilo-Benjamini
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Pascoe
authors.forename: David J
authors.initials: DJ
authors.lastname: Maggs
authors.forename: Bruno H
authors.initials: BH
authors.lastname: Pypendop
authors.forename: Eric G
authors.initials: EG
authors.lastname: Johnson
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.forename: Erik R
authors.initials: ER
authors.lastname: Wisner
mesh_terms: D000765:Anesthesia, Conduction / Q000379:methods / Q000662:veterinary*; D000772:Anesthesia, Local / Q000379:methods / Q000662:veterinary; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage / Q000494:pharmacology*; D002415:Cats; D018592:Cross-Over Studies; D005123:Eye / Q000187:drug effects*; D005260:Female; D007429:Intraocular Pressure / Q000187:drug effects; D014065:Tonometry, Ocular / Q000662:veterinary
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine