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Ocular System

Oculocardiac reflex (OCR)

Oculocardiac reflex (OCR), also known as the Aschner reflex or trigeminovagal reflex (TVR), is a reflux resulting in severe bradycardia (decrease in heart rate (HR) of > 20%) caused by traction applied to the extraocular muscles (especially the medial rectus muscle), pressure on the globe, ocular trauma, traction on the conjunctiva, or occasionally by placement of a retrobulbar block.

Oculocardiac reflex (OCR), also known as the Aschner reflex or trigeminovagal reflex (TVR), is a reflux resulting in severe bradycardia (decrease in heart rate (HR) of > 20%) caused by traction applied to the extraocular muscles (especially the medial rectus muscle), pressure on the globe, ocular trauma, traction on the conjunctiva, or occasionally by placement of a retrobulbar block.

  • Rate of OCR occurrence rate in ophthalmologic surgeries: 63-68%

Physiology

  • Afferent stimulus via ophthalmic branch of cranial nerve V (trigeminal nerve)
  • Efferent stimulus via cranial nerve X (vagus nerve)
Print
The oculocardiac reflex pathway. Divisions of the trigeminal nerve: V1, ophthalmic; V2, maxillary; and V3, mandibular. ICA, Internal carotid artery. | Murray MJ, Rose SH, Wedel DJ, et al. Faust Anesthesiology Review. 4th ed. Philadelphia: Elsevier; 2013.

OCR pathway:

The afferent OCR limb is via the long ciliary nerve and the short ciliary nerves. The latter first come together at the ciliary ganglion; these two inputs then converge to form the ophthalmic division of the trigeminal nerve. The efferent limb of the OCR is vagal via the cardiac depressor nerve.

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Oculocardiac reflex (OCR): The ophthalmic division of the trigeminal nerve (afferent limb) is stimulated via the long and short ciliary nerves. Afferent impulses are transmitted to the gasserian ganglion and main trigeminal sensory nucleus. From there, they are relayed to the efferent (motor) nucleus of the vagus nerve. The efferent pathway includes the vagus nerve and the cardiac depressor nerve. | Vassallo SA, Ferrari LR: Anesthesia for ophthalmology. In Coté CJ, Ryan JF, Todres ID, et al [eds]: A Practice of Anesthesia for Infants and Children, 2nd ed. Philadelphia, WB Saunders, 1993, p 325.

Clinical features

  • Sinus bradycardia (M/C)
  • Hypotension
  • Atrioventricular block
  • Ventricular ectopy
  • Asystole (rare)

Management

  • Immediate cessation of the stimuli
  • If the reflex recurs:
    • IV atropine (glycopyrrolate likely will not provide a strong enough anticholinergic boost) or lidocaine infiltration of the extraocular muscles
  • Severely decreased CO and hypotension:
    • IV epinephrine or external pacing

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