Ocular Procedures Performed with Local Anaesthetic Blocks

Time: Variable
Pain: Minimal
Position: Supine, face parallel to ceiling
Blood loss: Negligible
Special: Hyaluronidase: Hydrolyses hyaluronan, reducing integrity of the extracellular matrix and ↑ tissue permeability

Local anaesthetic with or without sedation for eye surgery is:

Techniques

Different methods for LA include:

  • Topical
    Provides corneal anaesthesia.
    • Adequate for cataract surgery by phacoemulsification
      Does not provide akinesia.
  • Peribulbar Block
    The most commonly used injection technique.
  • Sub-Tenon’s Block
    A useful alternative when a peri-bulbar block is contraindicated.
  • Retrobulbar block
    Produces better akinesis and lower IOP than a peribulbar block, but has greater associated risks and is essentially superseded by a peribulbar block.

Considerations

  • B
    • COAD
      CO2 retention may occur under the drapes. High-flow oxygen under the drapes may reduce this.
    • Ability to lie flat for up to 30 minutes
  • C
    • Hypertension
      High SBP may ↑ risk of bleeding, especially with use of phenylephrine drops to dilate the eye. Normal antihypertensives should be taken.
  • D
    • Axial length
      Determines which technique would be more appropriate.
    • Ability to obey commands
    • Anxiety levels around LA and eye
  • H
    • Clotting status
      • Bleeding issues
      • Presence of anticoagulants
        Clotting profile should be checked within 24 hours for patients on anticoagulants.
        • Use of antiplatelet agents including aspirin
        • Warfarin and INR if applicable
        • NOACs

Preparation

  • Standard ANZCA monitoring
  • IV Access

Induction

  • Time out
  • Give sedation
    Many appropriate techniques:
    • Midazolam 0.5-2mg
    • Propofol 10-30mg with alfentanil 250ug
    • Propofol 10-20 mg with ketamine 10mg and alfentanil 100-250ug
  • Apply topical local anaesthetic drops
    3 drops of 1% amethocaine or oxybuprocaine into the eye. Repeat 3 times at 1 minutely intervals, as required.

References

  1. Ripart J, Mehrige K, Rocca RD. Local & Regional Anesthesia for Eye Surgery. NYSORA.
  2. Royal College of Anaesthetists and Royal College of Opthalmologists. Local Anaesthesia in Opthalmic Surgery. 2012.