Ophthalmic surgery and the oculocardiac reflex
Stem
A 4-year-old girl, 16 kg, is having bilateral medial rectus recession for esotropia under general anesthesia with sevoflurane through a laryngeal mask airway, breathing spontaneously. She is otherwise healthy. As the surgeon hooks and pulls on the left medial rectus, her heart rate falls from 118 to 54, and the rhythm is sinus bradycardia. Blood pressure is 74/38 and end-tidal CO2 is 52 mmHg.
Question
What is happening, and what will you do?
Ideal answer
HeadlineThe oculocardiac reflex from medial rectus traction. I tell the surgeon to release the muscle now: stopping the stimulus is definitive, and the rate usually recovers within seconds.1 2
- Assist her breathing with 100% oxygen, anesthetic deep enough, because an end-tidal CO2 of 52 means hypoventilation, and hypercarbia, hypoxemia and acidosis all intensify the reflex.2
- If it persists or recurs: atropine 10–20 mcg/kg, 160–320 mcg for her, or glycopyrrolate 10 mcg/kg, 160 mcg.1
- Gentle resumption once she is stable, because the reflex fatigues with repeated traction.1
- Continuous ECG, atropine drawn up for the second eye, because the reflex can recur there; watching for escape rhythms, ventricular ectopy or asystole.
- Prophylaxis for vomiting, which is very common after strabismus surgery.2
Breaking down the answer
- Why release beats atropine — no drug outperforms releasing the muscle, and saying so first shows judgment.2
- Know the arc — afferent through the ciliary nerves and ophthalmic division of the trigeminal nerve, efferent through the vagus to the sinoatrial node.2 The examiner often asks for both limbs.
- Why she is hypercarbic — a spontaneously breathing child under a deep volatile anesthetic is a set-up for hypercarbia, so I assist or control ventilation.2
- Anesthetic choice matters — propofol with remifentanil increases the incidence compared with volatile agents, and ketamine has been associated with a lower incidence.1 2
- Prophylaxis is a judgment call — anticholinergic pretreatment reduces the incidence, but routine use is controversial.1 Changes if: a history of a severe reflex or conduction disease; I pretreat.
- Not only strabismus — the reflex also occurs with retrobulbar blocks, orbital trauma, sinus and transsphenoidal surgery.1
Follow-up question
The surgeon moves to the right eye and pulls on the medial rectus without warning. The ECG shows asystole, and three seconds later there is still no complex.
What do you do?
Follow-up answer
HeadlineAsystole from the oculocardiac reflex, a recognized progression from bradycardia.2 I say loudly: "Asystole, let go of the muscle."
I make sure the traction is released, turn off the volatile, ventilate with 100% oxygen, and give atropine 20 mcg/kg, 320 mcg, immediately. If there is no rhythm within seconds, I start chest compressions, call for help and the pediatric code cart, and follow the pediatric ALS asystole algorithm, including epinephrine. Once she has a perfusing rhythm, I discuss with the surgeon whether to continue; if we do, I pretreat before further traction, ask for gentle, graded tension and a warning before each pull, and watch the ECG closely. I debrief the team afterward.
Pitfalls that cost points
- Reaching for atropine before telling the surgeon to stop.
- Forgetting that the retrobulbar injection itself can trigger the reflex.1
Rapid-fire
Q: How is the oculocardiac reflex defined? A: A fall in heart rate of more than 20% for 5 seconds or more with globe pressure or extraocular muscle traction.1
Q: Who is most at risk? A: Children; the reported incidence ranges from 14% to 90% and falls with age.2
Q: Why avoid nitrous oxide after retinal surgery with an intraocular gas bubble? A: It expands gas-filled spaces, so retinal surgery that leaves an intraocular gas bubble is a contraindication.3
Q: Does a retrobulbar block prevent the reflex? A: It blunts the afferent limb, but the injection itself can trigger it.1
Q: Apnea and a dilated opposite pupil 10 minutes after a retrobulbar block? A: Brainstem anesthesia from injection into the optic nerve sheath, with onset over 5–50 minutes; I ventilate and support the circulation until it wears off, usually with full recovery.4
Q: How common is vomiting after pediatric strabismus surgery? A: Reported as high as 85%.2
Numbers to know
| Item | Value |
|---|---|
| Definition | HR fall >20% for ≥5 s1 |
| Atropine | 10–20 mcg/kg IV (160–320 mcg for her)1 |
| Glycopyrrolate | 10 mcg/kg IV (160 mcg)1 |
| Incidence | 14–90%, higher in children2 |
| PONV after pediatric strabismus surgery | Up to 85%2 |
Links
- ponv, Volatile agents and nitrous oxide: when and when not, ACLS adapted to the operating room, Emergence delirium, Dexmedetomidine and ketamine
- OpenAnesthesia: oculocardiac reflex; PALS bradycardia and arrest algorithms
Sources
- 1.Oculocardiac reflex · OpenAnesthesia · openanesthesia.org
- 2.Oculocardiac Reflex · StatPearls · statpearls.com
- 3.Nitrous oxide · OpenAnesthesia · openanesthesia.org
- 4.A Case of Brainstem Anesthesia after Retrobulbar Block for Globe Rupture Repair · Case Reports in Anesthesiology (Nanda, Ross, Kerr), 2021 · europepmc.orgOnset over 5-50 min (average 20.5) after optic nerve sheath injection; usually full recovery.
Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.