Oculocardiac Reflex

Excerpt

The oculocardiac reflex (OCR), also known as the Aschner reflex or trigeminovagal reflex, was first described in 1908 as a heart rate diminishment when direct pressure is placed on the eyeball. The heart rate is characteristically decreased by over 20% following globe pressure or extraocular muscle traction. The OCR typically leads to sinus bradycardia, though arterial pressure reduction, arrhythmia, asystole, and even cardiac arrest have also been documented arising from this reflex. Ophthalmic procedures, particularly strabismus surgery, often induce the OCR. Facial trauma, regional anesthetic nerve blocks, and mechanical stimulation may also trigger this reflex.

The OCR's incidence is reported to be anywhere from 14% to 90% and decreases with age. Pediatric populations face the highest risk of OCR development due to their increased susceptibility. Young individuals are also particularly vulnerable to OCR's complications due to their heavy dependence on the heart rate for maintaining cardiac output. The OCR's varying occurrence and severity are linked to factors like hypoxia, hypercarbia, acidosis, and the anesthetic agent type employed during surgery.