Overview of Lateral Orbital Canthotomy
Orbital compartment syndrome (OCS) happens when pressure builds up rapidly within the eye socket, which can potentially lead to permanent loss of vision. The condition was first noted by Gordan and McRae in the 1950’s following a cheekbone fracture. This happens because the optic nerve, which is necessary for vision, and retinal function, get affected due to decreased blood supply. This can eventually lead to a severe loss of vision. Just like other types of compartment syndromes which are caused by increasing pressure and cause severe harm and permanent damage, OCS also develops in a similar way.
OCS typically happens when an impact or mass is formed within the eye socket. Any situation that leads to a rise in eye socket pressure can result in OCS. Circumstances that cause this increase in pressure can be instances of heavy bleeding or gathering of fluids in the eye socket. Non-injury causes of bleeding can be due to surgeries such as those involving the eye socket, eyelid and tear duct surgeries. Bleeding in the eye socket can also be caused by common anesthetic procedures such as injections of local anesthetics near or behind the eyeball. Also, excessive bleeding related to nasal cavity-tumors, tumors causing spread of disease due to orbital-lymphatic malformation and any other processes outside of the eye can lead to OCS.
Non-bleeding causes of OCS can include lengthy surgeries where the patient is lying on their stomach (such as spinal surgery), facial and around-the-eye burns, and large-scale fluid replacement for severe burns, all of which can lead to fluid accumulation within the eye socket. Other rarer causes of OCS include air trapped in the eye socket due to fractures in the sinuses.
All emergency doctors should also be alert of a condition called orbital cellulitis, regardless of whether an abscess is present or not, as it could possibly lead to OCS.
OCS is a serious eye emergency that can be caused by many different issues and all emergency doctors should be able to diagnose this condition clinically. Understanding how to perform a surgical procedure called lateral orbital canthotomy and cantholysis (LOC) is crucial to help stop permanent vision loss. OCS can cause the eyeball to protrude, which puts pressure on the optic nerve in addition to the compression from the increased pressure within the eye socket. The goal of LOC is to cut the eyelid free from its attachment to the eye socket bone, to release the built-up pressure within the eye socket.
Quick consultation with an eye specialist is ideally the best course of action, but damage to the optic nerve due to OCS can happen very quickly. Better outcomes can be achieved if interventions such as LOC are completed promptly, preferably within 2 hours of symptoms starting to show.
Anatomy and Physiology of Lateral Orbital Canthotomy
The orbital cavity is like a pyramid-shaped, small room, about 30 mL in size that acts as a home for the eyeball. It is bordered on the top and bottom by tissue bands called the superior and inferior orbital septa. Interestingly, the orbital cavity is built by seven different bones of the skull. The upper and middle sides of the cavity are formed by the frontal bone, while the maxilla or roof-of-mouth bone forms the inner borders. On the outer edges, the cheekbone or zygomatic bone provides the structure.
The ethmoid and lacrimal bones, found at the inner corner of the eyes, form the inner borders at the back of the cavity. A tiny part of the posterior or back wall of the orbital cavity is made by the palatine bone while the rest of the back and outer walls are made up of the sphenoid bones.
Inside this bone-built cavity, the globe or eyeball, which is about 7 mL in size, is held firmly in place at the back by the optic nerve and the ophthalmic artery. This connection keeps the eyeball from moving too much forward. To prevent the eyeball from popping out, it is held in place from the front by the medial and lateral canthal tendons (muscles that attach the eyelids to the walls of the orbital cavity).
Each eyelid is shaped by something called a tarsal plate, a firm band of tissue. These plates are attached at the back to the conjunctiva, a thin layer that covers the front of the eye. Each eyelid meets at the corners of the eye, forming the medial and lateral canthi. The open shape of the eyelid is due to the palpebral fissure, the visible gap between the upper and lower eyelids.
The bones and these different structures together form the borders of the orbital cavity, the house for the eye.
Why do People Need Lateral Orbital Canthotomy
Orbital Compartment Syndrome (OCS) is a condition that can rapidly lead to permanent blindness. It’s a clinical diagnosis, meaning it’s based on observing symptoms rather than specific tests. It could be a result from a facial injury, an infection of the sinus or eye socket, a concern for bleeding behind the eye, or recent eye surgery.
When someone presents with symptoms like bulging eyes (proptosis), reduced clearness of vision, increased pressure within the eye (elevated intraocular pressures or IOP), limited eye muscle movement, and/or a pupil defect which affects the eye’s response to light, doctors may consider an urgent procedure called a lateral orbital canthotomy with cantholysis. This procedure can help relieve the pressure in the eye and reduce the risk of blindness.
Measurements of the pressure within the eye are also a crucial part of identifying this condition. If the pressure (IOP) is 40 mmHg or higher, this is seen as a signal that intervention is needed. In some cases, patients might be unconscious—such as those with an injury around the eye—or unable to give a history or describe their symptoms. In such cases, if OCS is suspected, doctors might decide to carry out an emergent lateral canthotomy, a surgical procedure performed to relieve pressure in the eye, as a precautionary measure.
When a Person Should Avoid Lateral Orbital Canthotomy
If a person’s eyeball, or “globe,” is suspected or confirmed to be ruptured, they should not have a certain surgery called a lateral orbital canthotomy. This condition can be guessed based on signs like a sunken eye – a condition known as “enophthalmos” – rather than a bulging or protruding one – known as “proptosis.” A CT scan, which is a type of medical imaging, can also be used to confirm the rupture. A globe rupture makes this surgery unsafe.
Equipment used for Lateral Orbital Canthotomy
To carry out a procedure known as a lateral orbital canthotomy, which is a surgical procedure on the eye’s outer corner, specific tools are necessary. Firstly, betadine prep is used to cleanse and sterilize the area. After this, the affected area is covered with a sterile drape to maintain cleanliness.
For the numbing agent, local anesthetic such as lidocaine with epinephrine, which varies from 1% to 2% can be used. This medication numbs the area so you won’t feel pain during the procedure.
In order to clean the area, normal saline or sterile water can be utilized. Then, a tool called a hemostat is used to control bleeding and to mark the area by creasing the skin. Lastly, forceps are used to lift up the skin and either a scalpel with a #10 blade or scissors are used for cutting, but scissors are generally preferred because they give doctors a better control.
All these tools are usually contained in what’s known as a standard laceration repair tray, which is a set of instruments used for wound treatment.
Who is needed to perform Lateral Orbital Canthotomy?
Eye doctors, also known as ophthalmologists, are usually the ones who carry out this procedure. However, other doctors who have experience with surgical procedures conducted right at the patient’s bedside can also do this. This could include emergency room doctors, trauma surgeons, general surgeons, or oral and maxillofacial surgeons (these are doctors who treat diseases, injuries and defects in the head, neck, face, jaws and the hard and soft tissues of the mouth and jaws). While it’s usually better to have an assistant to help hand over the needed materials and make sure everything’s safe, this procedure can still be done safely and in a clean way by just one doctor.
Preparing for Lateral Orbital Canthotomy
Preparing for this urgent bedside procedure is straightforward and doesn’t require much more than gathering the necessary tools. It’s also important to have good lighting, especially if there’s a lot of bleeding or dried blood that needs to be cleaned. Cleaning the area is vital because it helps doctors to see all the important anatomical landmarks clearly.
The patient should lie flat on their stomach for the procedure. If there’s enough time, the doctors may also give the patient some medication to help them relax. This is all to ensure that the procedure goes as smoothly as possible.
How is Lateral Orbital Canthotomy performed
The process of performing a lateral orbital canthotomy and Cantholysis, which is a medical procedure that can prevent loss of vision, is a quick one and can be completed in a few distinct steps:
1. Start by numbing the area where the cut will be made. Use a thin needle (25-gauge) to inject about two milliliters of a numbing medicine known as 1% to 2% lidocaine with a drug called epinephrine. This should be done into the lateral canthus, which is the outer corner of the eye, and the needle should be pointed away from the eyeball.
2. While the local anesthetic is working to numb the area, use a saline solution to clean the canthus and the eye, ensuring to remove any foreign objects or debris. Be careful not to injure the eyeball during this step.
3. Gently squeeze the outer corner of the lower eyelid using a surgical tool called a hemostat. This does two things: It marks the spot where the cut will be made and it makes the skin thinner so the cut can be made more easily.
4. Lift the skin around the marked area using forceps or medical scissors while also making a 1 to 2 cm cut at the marked spot using a surgical blade or scissors. The cut should be made from the outer corner of the eye (the lateral canthus) and should continue in an outward direction. Continue to move aside the tissue until you see the lateral canthal tendon. This tendon is a band of fibrous tissue that sits around the eye. Once you find the lower part of this tendon (inferior crus), direct the blade or scissors downward and strum the tendon. This involves rubbing the tendon with the edge of the blade or scissors. Once you’ve done this, cut the fibers of the tendon until the lower eyelid becomes completely loose. Check the pressure inside the eye. If it’s still too high, you can repeat this procedure on the upper part of the lateral canthal tendon.
By following these steps, the pressure inside the eye should be relieved immediately. The ability to see can improve shortly after the procedure; however, the final improvement in vision will depend on how much irreversible damage happened before the procedure was performed.
Possible Complications of Lateral Orbital Canthotomy
There are mainly five complications that could happen after an emergency procedure to relieve pressure on the eye, called a lateral orbital canthotomy. These include not completely cutting the canthus (the corner of the eye where the upper and lower eyelids meet), accidentally causing injury or rupture to the eye globe (the eye ball) or nearby structures (this is rare), loss of proper lower eyelid support, eyelid misplacement, infection, and bleeding.
Globe injury or rupture might happen because of the medical instruments used in the procedure – like forceps, scissors, surgical blades, or hemostats. There could also be other complications like drooping of the upper eyelid (ptosis), which might happen if there’s damage to certain upper eye muscles called the levator aponeurosis and Müller’s muscle. Damage to the lacrimal gland (which produces tears) and Meibomian glands (small oil glands on the edge of the eyelids) are also possible as they’re located at the top of the eye socket.
Less common complications include bleeding and infection. Like all surgeries, there’s a risk of getting an infection from breaking down natural barriers of the eye or from the tools used in the procedure. There’s also a risk of bleeding, especially if the surgery damages the lacrimal artery, which gives blood supply to the eye and surrounding areas.
What Else Should I Know About Lateral Orbital Canthotomy?
When patients experience sudden loss of vision in one eye, it may be due to a medical condition called Orbital Compartment Syndrome (OCS). This is usually a medical emergency. If the patient is treated within two hours of the vision loss, chances for recovering vision are better. This is often done with an operation called lateral orbital canthotomy, which helps relieve pressure on the eye.
For example, an 80-year-old man from Denmark who suddenly lost vision in one eye, showed great improvement after this procedure. He had fallen and hurt his eye, and his eye pressure was very high. Just five minutes after the operation, he started seeing some movement. After thirty minutes, his eye pressure had reduced significantly, and vision was much improved. Six months later, his only complaint was some color distortion in the affected eye.
A second patient, a 45-year-old man from Philadelphia who was attacked with a blunt object, also experienced significant vision improvement after the operation. His eye pressure was very high and he had no light perception in the affected eye. Immediately after the operation, his pain improved and his eye pressure decreased. At the end of his hospital stay, he had regained almost normal vision in the affected eye.
A third case, a 32-year-old man, was assaulted and complained of vision loss. After the operation, he regained full vision in his eye overnight and was discharged the next day with a follow-up appointment with an eye specialist.
While eye specialists are best suited to perform this operation, it’s often necessary for emergency room doctors to do it right away, as waiting could result in permanent vision loss. Some reports suggest that not all emergency medicine doctors feel confident performing this operation, which can result in less than optimal outcomes for the patient. It’s essential that all emergency medicine doctors become familiar with this procedure to prevent unnecessary vision loss.
