Anesthesia Considerations for Strabismus Surgery

Strabismus surgery is commonly performed in pediatric and adult patients to correct ocular misalignment. It involves extraocular muscle recession, resection, or transposition. Proper anesthetic management is crucial due to the risk of the oculocardiac reflex (OCR), postoperative nausea and vomiting (PONV), and airway concerns in children.


1. Preoperative Considerations

A. Patient Assessment

  • Pediatric vs. Adult Considerations
    • Most cases involve children, requiring careful airway assessment and anxiolysis.
    • Adults may need local anesthesia with sedation, but general anesthesia (GA) is preferred.
  • Systemic Evaluation
    • Neurological disorders (e.g., cerebral palsy) are common in congenital strabismus cases.
    • Congenital syndromes (e.g., Down syndrome) may have difficult airways.
    • Coexisting refractive errors (e.g., myopia, hyperopia) should be noted.
  • Medication Review
    • Anticonvulsants (if present) should be continued.
    • Anticholinergics (e.g., atropine premedication) may help reduce the oculocardiac reflex (OCR).

B. Ophthalmic Considerations

  • Oculocardiac Reflex (OCR):
    • Triggered by traction on extraocular muscles (especially medial rectus).
    • Causes bradycardia, hypotension, arrhythmias, or even asystole.


2. Anesthetic Techniques

A. General Anesthesia (Preferred in Most Cases)

  • Induction:
    • Inhalational induction (sevoflurane) preferred in children.
    • IV induction (propofol) in cooperative patients.
  • Airway Management:
    • LMA preferred for short procedures.
    • Endotracheal tube (ETT) if prolonged or if OCR occurs.
  • Muscle Relaxants:
    • Avoid suxamethonium (can cause transient extraocular muscle contraction, increasing intraocular pressure).
    • Rocuronium + Sugammadex for neuromuscular blockade if needed.
  • Maintenance:
    • Sevoflurane or TIVA (Total Intravenous Anesthesia).
    • Avoid nitrous oxide (N₂O can expand air pockets if gas injection is used in some advanced cases).

B. Local Anesthesia (for Adults in Some Cases)

  • Peribulbar block or topical anesthesia combined with sedation.
  • Drugs Used: Lignocaine 2% + Bupivacaine 0.5% ± Hyaluronidase.


3. Intraoperative Concerns

A. Oculocardiac Reflex (OCR)

  • Triggered by:
    • Pressure on the globe.
    • Traction on extraocular muscles (esp. medial rectus).
  • Symptoms: Bradycardia, asystole.
  • Management:
    • Stop the stimulus (surgeon releases traction).
    • Ensure adequate depth of anesthesia.
    • IV atropine (0.01 mg/kg) if bradycardia persists.

B. Postoperative Nausea and Vomiting (PONV)

  • Very common due to vagal stimulation.
  • Prevention:
    • Ondansetron 0.1 mg/kg IV.
    • Dexamethasone 0.1 mg/kg IV.

C. Pain Control

  • Minimal postoperative pain; managed with:
    • Paracetamol (IV or oral).
    • NSAIDs (if no contraindications).


4. Postoperative Considerations

  • Emergence Delirium (ED): Common in children; minimize with TIVA and dexmedetomidine.
  • Ocular Discomfort: Due to muscle manipulation; usually self-limiting.
  • PONV: Persistent nausea requires rescue antiemetics (e.g., metoclopramide, promethazine).



MCQs for Exam Preparation

  1. Which muscle is most commonly associated with the oculocardiac reflex?
    a) Lateral rectus
    b) Medial rectus
    c) Inferior oblique
    d) Superior rectus
    Answer: b) Medial rectus
  2. What is the first step in managing the oculocardiac reflex during surgery?
    a) IV atropine
    b) Increase depth of anesthesia
    c) Stop surgical stimulus
    d) Administer adrenaline
    Answer: c) Stop surgical stimulus
  3. Which of the following is the best choice for maintaining anesthesia in strabismus surgery?
    a) Sevoflurane
    b) Desflurane
    c) Nitrous oxide
    d) Halothane
    Answer: a) Sevoflurane
  4. Which of the following drugs is most effective for preventing PONV in strabismus surgery?
    a) Midazolam
    b) Atropine
    c) Ondansetron
    d) Propofol
    Answer: c) Ondansetron
  5. Why is suxamethonium avoided in strabismus surgery?
    a) It increases intraocular pressure.
    b) It causes bradycardia.
    c) It leads to excessive sedation.
    d) It increases the risk of bleeding.
    Answer: a) It increases intraocular pressure.