To the Editor: The oculocardiac reflex is a potentially life-threatening phenomenon requiring prompt recognition and management. It is defined as a 20% or greater reduction in heart rate and/or the presence of arrhythmias during stimulation of the orbital contents.1 It is most commonly encountered in the context of paediatric squint surgery.

We report its occurrence in a young healthy adult man after a traumatic facial injury. While being transported to hospital by ambulance, he had intermittent bradycardia, with a heart rate as low as 38 beats/min, and was administered a 1 g dose of intravenous atropine. His medical and ocular histories were unremarkable, and he had no history of unexplained syncope.

In the emergency department, his heart rate remained low (40 beats/min) and his blood pressure was 122/52 mmHg. There was diffuse periorbital lid swelling and bony tenderness along the inferolateral orbital margin. He had restricted upgaze of his left eye; during this manoeuvre, his heart rate dropped to 20 beats/min and he developed hypotension, with a blood pressure of 92/48 mmHg. He was given three intravenous 500 μg boluses of atropine to improve his haemodynamic condition.

An electrocardiogram showed sinus bradycardia, and subsequent recordings showed intermittent Mobitz II second-degree atrioventricular block. A computed tomography scan of the left orbit showed a moderately displaced fracture of the orbital floor involving the maxillary bone, with entrapment of orbital fat and the inferior rectus muscle (Box).

Given the presence of the oculocardiac reflex with haemodynamic compromise, the fracture was immediately repaired surgically. Postoperatively, the patient’s blood pressure was 134/90 mmHg and his heart rate was 86 beats/min, with normal sinus rhythm. He recovered full eye movement, and no further oculocardiac reflex was recorded. He remained well 1 year after discharge.

The oculocardiac reflex was first described by Aschner as a slowing of the radial pulse when pressure was applied to the eye.2 It is a rare but recognised occurrence among young healthy adults with orbital fractures. Clinical manifestations of the reflex may include bradycardia, hypotension, nausea, vomiting and syncope.3 The reflex is acknowledged as an important indication for immediate surgical repair of the orbit.4 In addition to reducing morbidity from the reflex, urgent repair is beneficial as it releases incarcerated soft tissue, leading to a more favourable outcome with less likelihood of squint.5

Cardiac decompensation due to traumatic facial injuries should alert clinicians to the possibility of the oculocardiac reflex and the need for urgent surgical intervention.

Computed tomography scans of the patient’s left orbit

Sagittal (A) and coronal (B) computed tomography scans showing left orbital floor fracture with entrapment of the inferior rectus muscle (arrows).