Oculocardiac Reflex - Everything You Need to Know

Introduction

Oculocardiac reflex (OCR) or Aschner reflex is a phenomenon that occurs when pressure applied to the eye causes the heart rate to slow down. The OCR has received substantial research in the disciplines of ophthalmology, anesthesia, and surgery since Aschner first characterized it in 1908. Several eye operations, such as strabismus (crossed eye) surgery, intraocular injections (injection into the eye), and retinal detachment repair (surgery for placing the retina back in its position), can have an impact on individuals who are experiencing this well-known and significant reflex. The trigeminal (the fifth cranial nerve) and ophthalmic nerves (a division of the trigeminal nerve) are involved in the vagally mediated reflex known as the OCR. The parasympathetic nervous system is activated when pressure is applied to the eye, and the afferent signal (signals carrying information to the central nervous system) follows these nerves to the brainstem. This causes the heart rate to drop and, in rare instances, can cause cardiac arrest. Healthcare workers must comprehend the OCR. Understanding the reflex can aid in preventing it or lessen its effects. The anatomy and physiology of the OCR, the kinds of ocular surgeries that can cause it, and management techniques will all be covered in this article.

What Are the Signs and Symptoms of an Oculocardiac Reflex?

The common signs of oculocardiac reflex are:

• Bradycardia (decreased rate of heartbeat).

• Lightheadedness or dizziness.

• Nausea and vomiting.

• Low blood pressure.

• Excessive sweating.

• Blurred vision.

What Is the Physiology Behind Oculocardiac Reflex?

• A reaction that is set off by pressure on the eyeball or manipulation of the extraocular muscles during eye surgery or trauma is the oculocardiac reflex, sometimes referred to as the Aschner reflex. A sign of this response, bradycardia, which is characterized by a drop in heart rate, can occasionally include nausea, vomiting, and changes in blood pressure.

• The trigeminal nerve's (fifth cranial nerve) and the vagus nerve's (tenth cranial nerve) relationship forms the basis of the physiology underlying the oculocardiac reflex. While the vagus nerve controls the parasympathetic nervous system (the nervous system responsible for relaxing the body) and controls heart rate, digestion, and other biological functions, the trigeminal nerve is in charge of sensation in the face and the cornea of the eye.

• When the extraocular muscles are contracted or moved, the trigeminal nerve transmits a message to the brainstem, which subsequently stimulates the vagus nerve. The vagus nerve is activated, which causes a reduction in heart rate as well as other parasympathetic symptoms including nausea and vomiting.

• The intraocular pressure, traction on the extraocular muscles, and even a minor touch to the eyeball can all cause the oculocardiac reflex to be activated. To prevent difficulties and maintain patient safety during eye surgery, surgeons and other medical professionals must be aware of this reflex.

What Are the Surgeries That May Cause Oculocardiac Reflex?

Oculocardiac reflex can result from several procedures, including:

• Surgery for Strabismus: Strabismus is a condition where the eyes are not correctly aligned. The extraocular muscles or the globe itself may need to be moved during surgery to treat this issue, which can result in OCR.

• Orbital Surgery: The manipulation of the eye or the surrounding structures during orbital decompression or fracture repair surgery can result in OCR.

• Cataract Surgery: A speculum, a tool used to hold the eye in position during cataract surgery, has the potential to activate the OCR if excessive pressure is applied.

• Glaucoma Surgery: A suction device or laser may be used during glaucoma surgery to lower intraocular pressure, which can also activate the OCR.

• Retinal Detachment Surgery: To stabilize the eye during surgery to reattach the retina, scleral buckles or other devices may be used. This may result in the OCR.

How to Manage Cases of Oculocardiac Reflex?

OCR is frequently observed after eye procedures, particularly when the extraocular muscles are manipulated. Prolonged periods of bradycardia can cause hypotension and cardiovascular collapse, thus it's critical to treat OCR right away. Here are some strategies for handling OCR cases:

• Early Detection: During the surgery, it is possible to detect OCR by keeping an eye on the patient's heart rate and rhythm. The surgeon may be made aware of the likelihood of OCR by the presence of bradycardia or an arrhythmia. Early detection is essential for effective OCR control.

• Stop the Stimuli: If OCR is detected, stop the stimulus that is triggering the reflex right away. For instance, the surgeon should refrain from adjusting the extraocular muscles during ophthalmic surgery. By doing so, you may be able to reduce your bradycardia and avoid further issues.

• Anesthesia Depth Increase: A good technique to control OCR is to increase the depth of anesthesia. Inhaled anesthetics or intravenous medications can be used to achieve this. Anesthesia induction can help to stifle the OCR and stop subsequent occurrences.

• Administration of Atropine: OCR may be treated with the drug atropine. It functions by inhibiting the parasympathetic nerve system, which is what makes bradycardia happen during OCR. Immediately administering atropine is advised, especially if the bradycardia is severe or protracted.

• Other Medications: OCR can also be treated with other drugs such as Glycopyrrolate, Scopolamine, and Neostigmine. These drugs function by inhibiting the parasympathetic nervous system's effects or by boosting the sympathetic nervous system's activity.

Conclusion

In conclusion, the oculocardiac reflex (OCR) is a frequent occurrence that can happen during a variety of ophthalmic procedures, particularly those that involve traction on the eyeball or manipulation of the extraocular muscles. The parasympathetic reaction that arises from mechanical pressure or traction on the eyeball sets off the reflex, which in rare instances can lead to bradycardia, hypotension, and even cardiac arrest. Although OCR is a well-known phenomenon, ophthalmic surgeons, anesthesiologists, and perioperative workers continue to have serious concerns about it. To avoid any negative effects, it is crucial to identify the OCR's warning signs and symptoms, such as bradycardia and hypotension, and to swiftly handle them. Healthcare practitioners can reduce the likelihood of unfavorable outcomes related to the OCR and guarantee the best patient results by using the proper management techniques and taking preventative actions.