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Ocular cardiac reflex

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https://eyewiki.aao.org/Oculocardiac_Reflex

Oculocardiac reflex (OCR)

The oculocardiac reflex, also called the Aschner reflex or trigeminovagal reflex, is a vagally mediated slowing of the heart caused by pressure or traction involving the eye or orbit. It is often defined as a heart-rate fall of more than 20% after ocular stimulation. AAO EyeWiki overview

Reflex arc

  • Stimulus: pressure on the globe, conjunctiva, or traction on an extraocular muscle, especially the medial rectus.
  • Afferent limb: ciliary nerves → ophthalmic division of trigeminal nerve (CN V1) → trigeminal sensory nucleus.
  • Efferent limb: vagus nerve (CN X) to the heart.
  • Effect: increased vagal tone causes reduced heart rate and contractility.
Miller's Anesthesia, 10e, p. 9714.

Clinical features

Most commonly:
  • Sinus bradycardia
Potentially severe:
  • AV block
  • Junctional rhythm or ventricular ectopics
  • Sinus arrest or asystole
  • Hypotension
  • Nausea and vomiting in conscious patients

Common triggers

  • Strabismus surgery and traction on extraocular muscles
  • Pressure on the eyeball during ophthalmic procedures
  • Retrobulbar block
  • Ocular or orbital trauma
  • Orbital-floor fracture with entrapped extraocular muscle
It is more frequent in children, particularly during strabismus surgery. Miller's Anesthesia, 10e, p. 9714.

Risk factors that intensify the response

  • Younger age
  • Hypoxia, hypercapnia, or acidosis
  • Light anesthesia
  • Repeated or forceful muscle traction
  • Opioid administration

Management during surgery

  1. Immediately stop the ocular traction or pressure. This is the primary action and usually terminates the reflex.
  2. Assess oxygenation, ventilation, anesthetic depth, blood pressure, and ECG rhythm.
  3. If bradycardia persists or is hemodynamically significant, give an IV anticholinergic such as atropine or glycopyrrolate under the anesthesia team's protocol.
  4. Treat sustained instability or asystole according to standard resuscitation protocols.
  5. Resume surgery cautiously only after recovery, often with gentler traction and appropriate anesthetic optimization.
Preventive anticholinergics may reduce OCR, but routine prophylaxis is debated, especially in adults. Morgan and Mikhail's Clinical Anesthesiology, 7e, p. 1448.

Key clinical point

In a person with an orbital fracture, bradycardia, nausea/vomiting, syncope, or heart block after eye movement or orbital manipulation can indicate extraocular-muscle entrapment with OCR. This requires urgent ophthalmic/maxillofacial assessment, not simple observation. AAO guidance on traumatic OCR
A recent systematic-review search did not identify an OCR-specific review within the last 2 years; related trigeminocardiac-reflex reviews should not substitute for perioperative ophthalmic guidance.
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