The oculocardiac reflex (OCR) is a reflex in which compression or traction on the extraocular muscles, eyeball, or conjunctiva triggers a decrease in heart rate of 20% or more. It is also known as the Aschner reflex or trigeminovagal reflex. It was first reported by Dagnini and Ascher in 1908.
OCR is considered a subtype of the trigeminocardiac reflex (TCR). The term TCR was proposed by Shelly & Church (1988), and OCR is classified as its periorbital type. 3)
The incidence varies greatly depending on the type of procedure.
Historically, it was used to terminate supraventricular tachycardia by vagal stimulation, but it is no longer performed due to high risk.
The incidence is highest during strabismus surgery at 56–68%, and occurs in 17–27% of orbital trauma cases. Fatal outcomes are reported in approximately 1 in 3,500 cases. The incidence is even higher in children.
The main cardiac findings are as follows.
Intraoperative Findings
Sinus bradycardia: Most common. Occurs immediately after traction of the extraocular muscles.
Arrhythmias: Atrioventricular block, ventricular tachycardia, ventricular fibrillation, etc.
Cardiac arrest: Rare but reported. There is a case of intraoperative cardiac arrest in an 11-year-old girl6).
Hypotension: Associated with a vagal-dominant state.
Findings at the time of trauma
Bradycardia: May occur immediately after trauma. Cases occurring outside the operating room have also been reported4).
Nausea, vomiting, somnolence: In cases of extraocular muscle entrapment, these may be mistaken for intracranial injury6).
Restricted eye movement: Restrictive strabismus due to entrapment of the extraocular muscle.
White-eyed blowout fracture: A pediatric fracture with no subconjunctival or subcutaneous hemorrhage, appearing mild externally, and easily overlooked6).
Lubbers et al. classify risk into three levels3).
| Risk Classification | Representative Surgery/Situation |
|---|---|
| Low risk | Temporomandibular joint surgery, LeFort I osteotomy, zygomatic elevation |
| Moderate risk | Skull base surgery |
| High risk | Ophthalmic surgery, orbital exenteration, orbital fracture in children with heart disease |
Other patient-related risk factors:
Children, patients with hypercapnia or hypoxemia, those using beta-blockers or calcium channel blockers, and patients with a history of heart disease are at high risk. Among surgical types, ophthalmic surgery and orbital exenteration are classified as high risk 3).
Intraoperative OCR is diagnosed through continuous monitoring.
Bradycardia in trauma patients requires differentiation from the following conditions.
Step 1: Remove stimulus
Immediate cessation of surgical manipulation: Stop all extraocular muscle traction, eyeball compression, and orbital manipulation.
Wait 10–20 seconds: In many cases, heart rate recovers with this alone.
Step 2: Drug intervention
Intravenous atropine: 0.02 mg/kg (JRC bradycardia algorithm). In adults, repeated doses of 0.25 mg every 2 minutes have been reported3).
If persistent: Prepare for CPR and contact an anesthesiologist.
The following are effective as prophylaxis before or during surgery.
First, immediately stop the operation causing the stimulation, such as traction on the extraocular muscles or pressure on the eyeball. Heart rate often recovers within 10–20 seconds. If it does not recover, administer atropine 0.02 mg/kg intravenously, and if cardiac arrest occurs, start CPR.
The OCR reflex arc involves the trigeminal nerve (CN V) and the vagus nerve (CN X).
Kharia et al. classify the broader TCR into the following three types 3).
The reasons for higher risk in children are the following two points.
There is also a subtype called gaze-evoked OCR. Cases have been reported where, after pterygium surgery, adhesions form between the conjunctiva, Tenon’s capsule, and sclera due to fibrin glue, leading to reproducible bradycardia triggered by eye movements in specific directions5). This indicates that OCR can occur from mechanical stimulation of the conjunctiva alone, even without direct traction on the extraocular muscles.
The oculocardiac reflex (OCR) is a reflex mediated by mechanical stimulation via a clear reflex arc from the trigeminal nerve to the vagus nerve, and it recovers quickly upon removal of the stimulus. Vasovagal syncope (VVS) is a systemic vasovagal reaction with different pathways, triggers, and course 5). Both present with bradycardia, but the context of occurrence is key to differentiation.
Eldweik & Aljneibi (2022) reported a case of a 21-year-old male after pterygium surgery in which a reproducible decrease in heart rate from 80–90 bpm to 55–60 bpm was observed after 10 seconds of right gaze 5). They suggested that fibrin glue promotes adhesion between Tenon’s capsule, conjunctiva, and sclera, leading to gaze-evoked OCR. This demonstrates that OCR can occur from mechanical stimulation of the conjunctiva alone, even without direct traction on the extraocular muscles.
Geller et al. (2025) reported OCR cases in a non-surgical setting (trauma patients) and cited Espahbodi (2015) to suggest that ketamine may counteract vagal stimulation more effectively than atropine 4).
Toyohara et al. (2022) reported a case of intraoperative cardiac arrest in an 11-year-old girl and noted that while preoperative steroid administration for orbital fractures may reduce swelling, it may also increase the incidence of intraoperative OCR 6). The benefits and risks of steroids should be evaluated individually.
Asaari SAH, Balasubramaniam D, Ramli N, et al. When brakes fail you: Oculocardiac reflex elicited by a retained foreign body in a penetrating orbital injury. Am J Ophthalmol Case Rep. 2024;34:102029.
Basnet A, Chug A, Simre S, et al. Comprehensive Management of Pediatric Orbital Fractures: A Case Series and Review of Literature. Cureus. 2024;16(4):e57915.
Kharia A, Janardhana Rao S, Dubey V, et al. Oculocardiac Reflex in a Patient With Maxillofacial Trauma: A Case Study and Literature Review. Cureus. 2024;16(5):e59528.
Geller JE, Daneshpooy S, Block S, et al. Oculocardiac reflex causing bradycardia in a trauma patient following firearm injury. Trauma Case Reports. 2025;60:101282.
Eldweik LT, Aljneibi S. Restrictive strabismus and gaze-evoked oculocardiac reflex following pterygium repair with fibrin glue. SAGE Open Med Case Rep. 2022;10:2050313X221122459.
Toyohara Y, Mito N, Nakagawa S, et al. Asystole Due to Oculocardiac Reflex during Surgical Repair of an Orbital Blowout Fracture. Plast Reconstr Surg Glob Open. 2022;10:e4544.
