Felis ISSN 2398-2950

Anesthesia: for ophthalmic surgery

Contributor(s): John Dodam, Sheilah Robertson, Claire Waters

Introduction

Alternatives

Topical analgesia

  • Useful for desensitizing the conjunctiva and cornea only.
  • Not suitable where sharp instruments will be used as the animal may move suddenly and unpredictably.
  • Facilitates examination of painful eyes, collection of samples, removal of foreign bodies and cannulation for flushing of the naso-lacrimal duct.
  • Topical anesthetic:
    • Should not be used repeatedly due to corneal damage and delayed healing.
    • Topical agents (USA) include:
      • Alcaine (proparacaine hydrochloride 0.5%)
      • AK-T-Caine (tetracaine hydrochloride 0.5%)
  • Long acting for prolonged desensitization - amethocaine 0.5-1% .

Infiltration of local anesthetic

  • Temperament of the cat may mean extra restraint required.
  • Small body weight requires careful dose selection to avoid inadvertent overdosage, 0.5-1% solutions are safer.
  • Direct injection of appropriate small volumes of lignocaine/lidocaine 0.5-1%   Lidocaine  solutions at site of proposed incision.
  • For minor/superficial surgery where sharp instruments will not be used next to the eye itself in debilitated or sedated animals.

Regional local analgesia

Retrobulbar block
  • An alternative to the use of neuromuscular blocking agents (muscle relaxants) where surgery on the eye is difficult due to retraction into the orbit Local anesthesia: retrobulbar.
  • General anesthesia is required to allow the injection of an appropriate small volume of lignocaine/lidocaine 0.5-1% Lidocaine solution via the conjunctival sac into the retrobulbar space.
  • A small bore needle is used to minimize trauma.
  • Do not inject intravascularly.
  • A beneficial fall in intraocular pressure is produced.
  • Causes mydriasis which is required for intraocular surgery.
  • Can cause an increase in intraocular pressure (IOP).

Preparation

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Requirements

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Procedure

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Maintenance

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Recovery

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Brunson D B (1980) Anesthesia in ophthalmic surgery. Veterinary Clinics of North America Small Animal Practice 10, 481-495 (Overview).
  • Crispin S M (1981) Anaesthesia for ophthalmic surgery. Proceedings of the Association of Veterinary Anaesthetists of Great Britain and Ireland 9, 171 (Review by a leading ophthalmologist).

Other sources of information

  • Hall, L W and Taylor P M (1994) Eds Anaesthesia of the Cat. London: Bailliere Tindall. pp 152, 268. ISBN 0 7020 1665 9.
  • Weaver, B M Q (1989) Anaesthesia for ophthalmic surgery. In: Manual of Anaesthesia for Small Animal Practice. Ed A D R Hilbery. Cheltenham: British Small Animal Veterinary Association. pp 101-105. ISBN 0 905214 09 9.
  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4


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