Overview of Extraocular Muscle Management With Orbital and Globe Trauma
Handling damage to the extraocular muscles (EOM) – the muscles that control eye movement – caused by trauma to the eyes, surrounding bone area (the orbit), or head can be complicated and varied. In scenarios of known eye or surrounding bone trauma, understanding the cause, type, and severity of the injury aids in determining the crucial parts of the physical exam. Detecting and responding to life-threatening injuries, following Advanced Trauma Life Support (ATLS) principles, takes priority over everything else. Such injuries are more frequently seen in incidents involving high-speed forces, like car accidents or firearm attacks.
Dealing with trauma to the EOMs can be viewed in two ways: situations where the EOMs are damaged and situations where they are not. Direct damage to the EOMs can range from mild – slight movement due to swelling or bleeding in nearby soft tissue; to moderate – bruising of the EOM itself; to severe – slicing, tearing, or trapping of the EOM due to a hard hit or a break in the orbit. Indirectly, the EOM’s ability to move may be affected due to injury to the cranial nerve (related to nerve control in the head and neck) or injury associated with head and neck trauma that affects the nerve centers in the brain. On the other hand, the EOMs may be intact but may need to be purposely detached from the eye to examine and repair open globe injuries (injuries where the eye wall is ruptured).
The presence or suspicion of an open globe injury and mechanical reasons for strabismus (a condition in which the eyes do not align with each other), or nerve involvement guides the planning and timing of surgery. The goal of managing extraocular muscles during emergency eye or orbit surgery is to limit the amount of scarring that could occur and result in strabismus.
Anatomy and Physiology of Extraocular Muscle Management With Orbital and Globe Trauma
The anatomy of the muscles that move our eyes, known as Extraocular Muscles (EOMs), and how they connect to our nerves is quite complicated. Any damage to the cranial nerves (the nerves that emerge directly from the brain), from several key points could lead to a condition known as strabismus, where the eyes do not properly align with each other. This article is mainly focused on how to handle issues with the EOMs that occur due to injuries to the eye or the area surrounding the eye.
The EOMs include the medial, inferior, lateral, and superior rectus muscles, as well as the superior and inferior oblique, and levator palpebrae superioris (LPS) which helps lift the upper eyelid. These muscles begin near a ring-like structure within the eye socket called the annulus of Zinn. They then attach to the eye near the eye’s equator. The area just behind where the rectus muscles attach to the eye (averaging about 0.3 mm in thickness) can potentially burst during eye trauma.
Understanding the muscles’ exact location and the connections can help surgeons recognize a hidden open wound during an examination.
The EOMs are linked together within a fibroelastic membrane, sort of like a pulley system, that prevents deep retraction of the muscle if it’s disinserted or cut towards the front, and may preserve muscle function on the initial examination, preventing sudden vision problems. Also surrounding the eye is the Tenon capsule, a membrane enveloping the eye and the beginning portion of the EOMs, forming a kind of sleeve within which the eye can move.
Things can get complicated when we have incidents of trauma that sever the muscles or if they detach for a procedure, these muscles must be isolated from their connections. For example, the medial rectus is the only muscle that does not have an oblique muscle running tangentially to it. Meaning if this muscle gets lost or slips, there is no point of reference for finding the muscle again.
Therefore, getting knowledge of the Extraocular Muscles (EOMs) – how they are connected, and their arrangement is beneficial while handling eye traumas and surgeries.
The oblique muscles go below their corresponding straight muscles and attach to the globe of the eye. Two in particular, the superior oblique and the inferior oblique, control the eye’s rotation. The superior oblique muscle originates from a structure called the trochlea, which acts as a pulley.
There are incidents where these muscles could get caught or tear in case of eye injuries, such as orbital fractures that lead to traumatic strabismus. The direction of the resulting misalignment of the eyes depends on where the fracture took place and how much of the Extraocular Muscle (EOM) was involved. Such injuries usually affect the floor and medial wall of the orbit leading to a blowout fracture.
While dealing with eye surgeries, surgeons also need to consider other factors like how the muscles connect widely with the globe and the possibility of the inferior oblique having more than one muscle belly.
Why do People Need Extraocular Muscle Management With Orbital and Globe Trauma
If your eye suddenly becomes painful, swollen, or bloody, or you have trouble seeing or moving your eye, it may be due to an injury. A damaged or penetrating object may have punctured your eye, which is a situation that requires immediate medical attention. The doctor may need to do surgery to fix the problem and prevent further damage. Occasionally, these injuries are deceptive and don’t show up immediately, or they can be hidden beneath tissue in the area, such as under a tear duct muscle; these are often only found when the eyeball is repaired.
An injury to your eye or the orbit, the bony cup that holds your eye, may also result in strabismus. Strabismus means that your eyes aren’t coordinated and do not look in the same direction at the same time. This can be caused by trauma to the nerves in the head, or if the injury affects the space inside your skull where your blood vessels are located. This can create everything from mild to extreme symptoms, and can pose a unique challenge to anyone trying to diagnose it. If you’re conscious and alert, having double vision or trouble looking in different directions can indicate that the doctor should check for restricted eye movement.
Forced duction tests can help to clarify if your symptoms are due to physical interference, such as something caught in the eye, or just because of swelling. These tests can be useful when you can’t participate in the exam. Sometimes, the movement of your eyes can trigger the oculocardiac reflex, which can cause slow heart rate, pain, and nausea. The history and examination are essential to know what treatment is needed. Sometimes, just waiting to let the swelling go down and the symptoms get better can give a better outcome. The waiting period is typically around two weeks, which allows the inflammation to resolve and can prevent excessive scarring.
However, if there are signs of muscle entrapment, immediate surgery is needed to fix the problem. This can prevent the eye muscle from shrinking or forming scar tissue due to low blood supply, which could result in strabismus. Blunt force injuries in adults have a 17.5% chance of traumatic strabismus, and about 10% in children. There are several signs that could indicate eye muscle entrapment, such as a dilated pupil, an oculocardiac reflex with eye movement, positive forced duction tests, strabismus, and increased eye pressure when looking up.
Your symptoms might suggest muscle entrapment or involvement, such as having double vision, experiencing nausea, vomiting, pain, or feeling faint when looking in a certain direction, or being very young. There’s also a chance that you may not experience any symptoms at all.
It’s important to be aware that certain situations could raise suspicions of eye muscle involvement. These situations might include a blow to the head or face like during a car accident, or with a forceful object, playing a sport, or a fall. Objects penetrating the eye, eyelid or orbit can also potentially cause damage. The type of repair needed will depend on the extent and severity of your injury.
When a Person Should Avoid Extraocular Muscle Management With Orbital and Globe Trauma
When it comes to eye examinations and treatments, serious, life-threatening conditions should be addressed first.
If there is a suspicion that a metal object has gotten inside the eye or the eye socket, it’s not safe to do a type of scan called a magnetic resonance imaging (MRI). The MRI could move the metal object and cause harm to the surrounding parts of the eye.
There are also special considerations when checking eye movement in patients with open injuries to the globe, which is the main part of the eye. If the wound is located at the back of the visible part of the eye (referred to as Zone 2 or 3 injuries), doctors might avoid or limit examining eye movements before the primary repair. Doing this isn’t strictly forbidden, but it might increase the risk of parts within the eye coming out. Before surgery on the eye, a certain type of anesthesia called a retrobulbar block isn’t safe if the globe of the eye is open.
Equipment used for Extraocular Muscle Management With Orbital and Globe Trauma
Eye and eye socket injuries can often happen at the same time as other injuries to the head, neck, and the rest of the body. To check for life-threatening injuries, your doctors use scans like CT scans of the head, neck, and abdomen. After dealing with these immediate injuries, your eye doctor can examine your eyes more thoroughly. This complete eye exam has eight parts, but the most urgent action is to protect the eye if there’s a risk of an open globe injury, which is when the outer covering of the eye is torn or cut. If this is suspected, nursing and emergency room staff will place a rigid shield over your eye to prevent further harm. Signs of a ruptured globe, such as visible eye tissue, can pause a regular eye exam until the eye is carefully repaired to avoid any further damage and loss of vision.
Dedicated CT scans of the orbiter (the bony eye socket) or face can assess the damage to the orbit and the muscles and tissues around the eye. An MRI, especially a dynamic MRI that has you look in different directions, provides detailed information about the length, contractility (ability to contract), and location of your eye relative to other structures in the socket. However, if there are any metallic foreign bodies in or around the eye, they need to be removed before an MRI. In an emergency, CT scans are usually more readily accessible than MRIs.
Depending on the type and extent of the eye trauma, your doctors will need different surgical instruments. If they suspect an open globe injury or a foreign body in the eye, they will require specific surgical trays. Should there be an eye socket fracture or a need to isolate eye muscles, other specific sets of tools are needed.
Generally, to manage the extraocular muscles (the muscles responsible for eye movement), the doctors would need various types of forceps, blunt scissors, an eyelid holder, curved needle holder, a measuring instrument called a caliper, hooks for isolating muscles, and sutures or special stitching materials for traction and for closing up any incisions after surgery.
When isolating muscles, different types of hooks can be helpful. Some are larger with rounded or flattened tips, while others are smaller and curved. Some hooks with a special groove to protect the white part of the eye during muscle imbrication (a surgical procedure to shorten a muscle) are also available. To detach the extraocular muscles, a double-armed needle with a flat top and bottom is useful. Double-armed means it has two ends, making it easier to reattach to the eyeball. The flat ends also reduce the risk of accidentally piercing the white part of the eyeball, especially when passing behind the muscle where it is thinnest.
Who is needed to perform Extraocular Muscle Management With Orbital and Globe Trauma?
Before any operation, it’s common for the patient to be seen by a doctor in the emergency room or someone who specializes in treating injuries. They do this to make sure any other injuries are taken care of first. Then, when it’s time for the surgery, there’s a lot of people there to help. First, there’s the ophthalmologist – this is just a fancy word for an eye doctor.
Sometimes, you might also see an orbital surgeon. This is a special type of eye doctor who knows how to do plastic surgery around the eyes. An otolaryngologist (also known as an Ear, Nose, and Throat doctor), or an oral and maxillofacial surgeon (a doctor who specializes in surgery of the face, mouth, and jaw) could also be part of the team.
Of course, there’s also a first (and maybe even a second) surgical assistant to help out during the operation, as well as the person who puts you to sleep — the anesthesia provider. Plus, there’s also a nurse and a surgical technician in the operating room. They all work together to ensure your operation goes smoothly and safely.
Preparing for Extraocular Muscle Management With Orbital and Globe Trauma
If a patient has been dealing with blurry vision for a long time due to conditions like lazy eye, cataracts, severe glaucoma, or certain eye illnesses, a doctor might mistake the problem as an eye misalignment caused by some sort of injury. However, this misalignment could be due to the eye’s reaction to the lack of good quality vision, which then turns inward (more common in young children) or outward (more common in older children and adults). Problems with the eyes might also happen due to past neck or head injuries, diseases in blood vessels, or an issue with an aneurysm causing a certain nerve in the brain to not function correctly. These health issues can confuse the cause of double vision and eye misalignment. Also, in these specific groups of patients, a special test that checks for eye movement restriction will come back normal.
Checking crucial basic things like how sharp a patient’s vision is and how well the eyes move can be difficult if the patient is either sleeping from medication or not cooperating. So, doing everything possible to complete the eye check-up, performing the necessary tests to see if there is restriction in eye movement, and doing a special type of X-ray known as a CT scan are very important.
Giving antibiotics before conducting an operation helps bring down the risk of getting an infection. Specifically, for an injury with the eyeball open, antibiotics belonging to a group known as fourth-generation fluoroquinolones are given before and after the surgery to prevent a severe eye infection. If there is a suspicion that certain specific types of bacteria may cause an infection, enhanced versions of certain antibiotics are recommended. In cases where there is suspicion of a fungal infection, antifungal treatment is suggested. Antibiotics are directly introduced into the eyeball in case of contamination or severe infection.
Antibiotics should be given around the time when an operation on the eyeball or the surrounding bone is conducted to prevent infection at the surgical site. There should be clear communication between different medical teams to ensure that the patient is not given too many medications and so that bacteria do not develop resistance to antibiotics.
General anesthesia or putting patients to sleep is the preferred way for performing operations to fix an open eyeball or fractured bone surrounding the eyeball. This helps the surgeons perform the operation properly because the patient feels numb and their muscles don’t move involuntarily.
How is Extraocular Muscle Management With Orbital and Globe Trauma performed
When repairing injuries to the eye, particularly those involving the muscles that control eye movement, the medical team must carefully examine the tissues and work through the necessary steps to repair any damage. This usually requires special tools and a strong light source for the best view.
Ahead of an operation, the surgeon will prepare and cleanse the eye area to minimize undue pressure on the eye ball, and a specialized device called an eyelid speculum is used to keep the eye open during the procedure.
The experts perform a specific procedure called ‘conjunctival peritomy’, which helps them see the eye muscles without causing too much pressure. They then carefully isolate the affected areas to prevent inadvertently severing important links within the eye. The specific location of the injury is crucial to identify the best approach. For instance, if the wound is situated behind a specific muscle, they will proceed with careful dissection in an area that allows good exposure.
Whether the eye muscles are left intact or split or retracted due to injury, the medical team will adopt certain specific strategies. The initial priority is to ensure that the eye ball is not damaged while the muscles are being reattached. If the muscle is only partially attached, they will see if the remaining part of the muscle could be detected deeper within the eye structure, and reattach it eventually.
Muscles that are detached might recoil back to a position deeper inside, but can be discovered by tracing the interconnections between muscles. Once the muscle is recovered, special fine-toothed instruments are used to secure it in place.
When the muscle has been reattached, the surgeon will then examine the eye ball further for any injuries that need to be repaired before reattaching the muscle. This process requires expert precision and caution, to ensure that the patient’s condition improves.
Once the repair and reattachment processes are complete, the surgical team will carefully close the eye tissue with a special yarn, and apply antibiotic ointment with a mild steroid to the eye for healing and recovery afterward.
For eye muscles that are detached and retracted far behind, the surgical team may have to consider alternative surgical approaches to gain access and reattach the muscle. Depending on the location and complexity of the injury, different surgical methods may need to be adopted.
Possible Complications of Extraocular Muscle Management With Orbital and Globe Trauma
After eye and orbit (the cavity that holds your eye) surgery, there are some serious complications that might require immediate treatment. These can include:
– Endophthalmitis: This is a severe eye infection within your eyeball.
– Persistent open globe wound: This is when the wound in your eye won’t heal.
– Sympathetic ophthalmia: This is a rare condition causing inflammation in both eyes after injury to one of them.
– Orbital compartment syndrome: This is a dangerous condition that can cause vision loss due to increased pressure in your eye socket.
– Orbital cellulitis: This is a serious infection that affects the tissues around your eyes.
– Orbital implant impingement on the optic nerve: This is when an implant (used to replace the volume of a missing eye) presses on the nerve that sends visual signals to your brain.
– Orbital implant impingement on the rectus muscle eliciting an oculocardiac reflex: This happens when the implant presses on a muscle in your eye, which in turn causes your heart to slow down.
– Bradycardia: This is when the heart rate becomes unusually slow. It’s caused by the oculocardiac reflex mentioned above.
– Scleral perforation: This happens when there’s a hole in the white part of the eye, which can lead to damage to the retina (the part in the back of your eye that helps with vision).
There are a few other complications as well:
– Anterior segment ischemia: This is a condition that occurs when the front of the eye doesn’t receive enough blood supply, especially if multiple rectus muscles (muscles that move the eye) are cut, detached, and then re-attached.
– Permanent mydriasis: This means the pupil of the eye is permanently dilated or enlarged.
– Infraorbital nerve hypoesthesia: This can lead to numbness or loss of sensation in parts of the face.
– Eyelid retraction: This means the upper or lower eyelid is pulled back from its normal position.
– Persistent diplopia: This is the persistent experience of seeing double.
Double vision can be a result of a variety of issues:
– The muscles controlling eye movement getting stuck to mesh or porous implants,
– The inadequate correction of an eye socket fracture,
– scarring from injury or orbital fat adherence,
– Damage to the tendon or pulley system leading to a specific type of eye movement problem called acquired Brown’s Syndrome,
– Removing too much of the eye muscle during surgery,
– Losing control (“slipping”) of an eye muscle,
– Paralysis of an eye muscle due to initial trauma,
– Contracture (shortening and hardening) of the antagonist muscle, which can work against the proper movement of your eye.
What Else Should I Know About Extraocular Muscle Management With Orbital and Globe Trauma?
During eye and eye socket emergencies, it’s essential to minimize injury to the EOM (eyeball’s muscles). This is important because it can prevent the need for strabismus surgery at a later date. Strabismus is a condition where the eyes don’t look in exactly the same direction at the same time. If caused by trauma, this can lead to problems like double vision and difficulty controlling the direction of gaze. This can make day-to-day tasks quite challenging. People with noticeable eye misalignment can also face problems in job situations.
Before any operation, it’s crucial for doctors to discuss all potential outcomes with the patient. This should include the possibility of needing an additional operation, apart from the ones needed to repair injuries to the eye or the bones of the eye socket. Long-term check-up appointments may be needed to address possible complications.
