Oculocardiac reflex

Oculocardiac reflex (OCR), also known as Aschner phenomenon or Aschner reflex, is a decrease in pulse rate associated with traction on the extraocular muscles and/or compression of the eyeball. The reflex is mediated by the vagus nerve and can be blocked by atropine.

Mechanism

The Oculocardiac reflex is a physiological process involving the vagus nerve's response to pressure on the eyeball or traction on the extraocular muscles. This pressure or traction stimulates the sensory afferent fibers of the trigeminal nerve, which then sends signals to the medulla oblongata. The medulla oblongata, in turn, stimulates the motor efferent fibers of the vagus nerve, leading to a decrease in heart rate.

Clinical significance

The oculocardiac reflex is of particular importance in ophthalmic and orbital surgery, as it can cause significant bradycardia, arrhythmias, and even cardiac arrest. It is most commonly seen during strabismus surgery in children. The reflex can be prevented or treated with the administration of anticholinergic drugs such as atropine or glycopyrrolate.

See also

• Oculorespiratory reflex
• Trigeminocardiac reflex