>> Review the anatomy and physiology of the eye.
>> Describe the prehospital assessment and management of eye injuries.
>> Discuss injury prevention as it relates to the eye.
Engine 94 and Rescue 94 respond to a popular sports complex known for housing large softball tournaments. The call is for a person struck in the face by a softball. On arrival, the crews find the pitcher of a neighboring fire department's softball team, who was struck by a softball directly between the eyes. The patient is awake, alert and, contradictory to initial reports, conscious. Blood and fluids are draining from both nares, and swelling is apparent around both orbits (see photo).
Bystanders report hearing an unusual sound coming from the bat when it connected with the ball, indicating illegal equipment. The crew immediately suspects increased ball velocity may have caused an orbit fracture or, worse, a basilar skull fracture.
The patient's thoracic spine is cleared by protocol, and he's placed on the gurney in a seated position of comfort with a cervical collar. Ice is applied to the area, both the eyes are covered and pain medication is administered en route to the trauma center. The bleeding slows, the vital signs remain stable and the crew doesn't note any change to the patient's level of consciousness.
Every year in the U.S., more than 2 million people visit an emergency department (ED) seeking treatment for eye injuries, according to the Centers for Disease Control. Trauma to the eye is the number one cause of blindness in people under 25. About 85% of eye injuries are caused by accidents, versus 15% resulting from assaults. More than 40% of eye injuries occur in the home.
Severe eye injury is a rare call for EMS, but when the extent of the injury does trigger a 9-1-1 call, your rapid assessment and care, with transport to an appropriate facility, can mean the difference between being permanently disabled and returning to normal life for your patient.
Anatomy & physiology
The bony socket that provides surrounding support for the eye is called the orbit. The orbit is bordered by a fragile set of bones: The zygomatic arch sits on the lateral or outside of the arch, the maxilla makes up the bottom of the orbit, the nasal and lacrimal bones form the medial or inside area of the orbit, the frontal bone borders the top of the orbit, and a small set of bones called the cribriform plate make up the inner walls of the eye socket that's part of the basilar skull.
The globe sits inside the orbit and is commonly referred to as the "eyeball." Covering the front of the orbit is the cornea, a transparent piece of skin. Behind the cornea is the iris, the colored part of the eye, which is made up of muscles that control the amount of light that enters through the pupil.
Directly behind the pupil is the lens, a transparent structure that focuses light rays to form an image on the retina. Located on the posterior aspect of the inside of the globe, the retina converts light into color and transmits electrical images down the optic nerve.
Behind the lens is a jelly-like substance called the vitreous humor, which fills the inside of the globe. The white part of the globe is called the sclera. The eye_s blood supply is delivered via the retinal artery and returns via the retinal vein. (See Figure 1, p. 58, for the basic anatomical structures of the orbit.)
The eye's movement is controlled by a series of muscles that form a matrix around the globe. The main muscle group is called the rectus, or straight muscle. The four muscles in this group are known as the inferior, superior, medial and lateral rectus. Smaller muscles, called obliques, assist in moving the eye in a coordinated way along the three horizontal planes, vertically and in rotation.
Assessment for injuries
Initial response to any eye emergency should include an assessment for scene safety. Determine whether you should wear eye protection to prevent injury from foreign objects or chemicals and whether additional precautions are also necessary.
Your first step is to ask the patient about changes in their vision or specific conditions or circumstances that would suggest a mechanism of injury. Also ask if they use contact lenses or prosthetics before beginning your exam.
Test their visual acuity (i.e., whether their vision is normally 20/20) and their visual field to reveal problems with direct or peripheral vision. If you don't have a visual acuity chart, ask your patient to count your raised fingers or read printed material from a distance.
It's also important to examine the eyes, including external areas, for symmetry, responsiveness and anything unusual, such as redness, inflammation, laceration or foreign bodies. Pay particular attention to the size and shape of the pupils.
Check to ensure their eyes converge and their pupils constrict as you bring an object toward their nose (known as "accommodation"). Check for pupillary reaction to light; slow reaction may indicate increased intracranial pressure, and unequal reaction may indicate a head injury.
In your detailed exam, lightly palpate the cheek bones and frontal skull to assess for fracture. An important predictor of a more serious eye injury is the loss of sensation to the forehead, eyelids, cheek, or upper or lower lips. This may indicate an impact significant enough to pitch or damage nerves within the eye.
Several categories of eye injury commonly require emergency care. The most prevalent is abrasion. More dangerous are direct or blunt trauma, penetrating objects or chemical burns. The biggest threat to vision is the enucleating of the eye.
Corneal abrasions, or scrapes to the outer surface of the eye, are some of the most frequent injuries requiring medical assistance. (See Table 1, JEMS August, p. 58, for a list of symptoms associated with corneal abrasion.) People also frequently report being poked in the eye or being injured during industrial work or a hobby. Although these injuries are relatively minor, they're often exacerbated by the person's impulsive action to rub the injured eye.
An injury similar to corneal abrasion can occur when a foreign body scratches the iris. This condition is known as iritis and presents with pain, excessive tearing and photophobia. Because it's an injury to the muscle, the patient may describe the pain as an ache. This condition is more commonly caused by blunt force to the eye with an object, such as a ball, fist, pool cue or club.
Corneal abrasions should be flushed with water or irrigated for at least 15-30 minutes. Never attempt to remove a foreign body embedded in the cornea or impaled in the globe. Stabilize it in place and cover the eye with a moist, sterile dressing or other protective barrier. Also, cover the unaffected eye to limit sympathetic movement. The eyes work as a team and, if one eye is left uncovered, the covered eye will want to move in the same direction as the uncovered one.
Significant blunt force to the eye, commonly sustained from sports equipment or a kick, can fracture the bones around the orbit and create a free-floating eye. Hyphema, or bleeding in the anterior chamber of the eye between the cornea and the iris, is a secondary condition to fracture and causes pain and blurred vision.
Fractures around the eye fall into three categories: orbital rim fracture, indirect orbital floor fracture and direct orbit fracture. An orbital rim fracture damages the zygomatic arch if the impact occurs on the lower part of the orbit or the frontal bone around the frontal sinus. An indirect orbital floor fracture results from a direct impact that disrupts the paper thin orbit or basilar skull, often leaving a hole in the floor that can impinge or trap the muscles and cause the eye to lock in place.
The loss of movement in one eye usually produces double vision. A direct orbit fracture transverses the socket and the rim, and can tear the retinal artery, optic nerve and retinal vein, causing severe bleeding. An impact of sufficient force to fracture the orbit in such a fashion could result in intracranial bleeding.
Damage to the zygomatic arch and other bones around the orbit is called a blow-out fracture. The inferior rectus muscle can become entrapped in the fracture, causing the patient to lose the ability to look upward with the affected eye. These fractures are painful, especially with eye movement, and can cause double vision. They may also result in a disrupted blood supply to the eye as the globe or socket becomes displaced, putting pressure on arteries or veins leading to or from the eye.
Orbital blow-out fractures require transport with elevation of the patient's head and cold packs applied around the orbit to reduce swelling. It's important to prevent the patient from blowing their nose because it can cause dramatic eyelid swelling.
A patient suspected of an orbital or blow-out fracture should be transported in a semi-seated position. Laying the patient flat may cause the globe or the entire structure to fall back into the posterior orbit, blocking the blood supply to the eye.
If there's sudden or partial blindness after trauma to the eye, treatment is needed within 90 minutes to save vision. In some cases, patients suffering orbital blow-out fracture present long after the onset of inflammation and initially ignore treatment.
Chemicals & burns
Chemical injuries and burns cause some of the most devastating eye injuries. Culprits of corneal flash burns range from the ultraviolet light produced from arc welders to tanning booths to the sun, with more serious burns resulting from acids or alkalis.
Although soap, sunscreen, tear gas and pepper spray are common irritants, they usually don't cause permanent problems. However, lye from drain cleaners or tanning solutions can splash into the eyes and cause severe burns, as can sulfuric acid exploding from a car battery during jumper-cable use.
Anhydrous ammonia, a chemical used in farming, frequently causes burn-induced blindness. Ammonia reacts with the eye's moisture to form nitric acid and scars the cornea. Any alkali or acid in the eye requires immediate attention in the ED and prompt notification to poison control.
Burns or chemical injuries should not be bandaged or covered with a cup or eye patch because the patient may have had contact lenses in place at the time of injury. Continually flush the eye under a faucet or shower. Every attempt should be made to keep the eye open, as residual chemicals on the eyelid may continue to contaminate the eye.
Objects that penetrate the globe or the orbit are true emergencies. If you encounter a patient with foreign objects embedded in or penetrating the globe, cover the eye with a small cup to ensure no pressure is applied. Any pressure to the eye can damage the blood supply or cause the loss of vitreous humor. Because it can't be replaced, loss of this substance causes immediate blindness, necessitating eye removal and possibly prosthetic placement. An eye oozing vitreous humor shouldn't be flushed but rather covered with some sort of rigid protection.
The most dramatic of all eye injuries is the enucleated eye. This type of injury is usually associated with significant trauma from a motor vehicle crash (MVC), gunshot or stabbing, or force from an object, like scissors, that penetrates the eye. When the body remains in motion following impact with an object, such as a tree branch impaling the eye of a skier, damage to the muscles that contain the eye in its socket is almost certain to occur. This type of injury has also been documented in assaults in which one person gouges the other's eye.
The most frequent intervention employed byEMS in cases of eye injury is flushing. Sterile water or 0.9% normal saline are the preferred solutions for irrigation. However, because large amounts are often required for chemical injuries to the eye, tap water or a supply from an eye-wash station is helpful.
Several methods are available to flush the eyes. A Morgan Lens is a small funnel-shaped device that fits over the anterior portion of the eye and connects to IV tubing to provide a continuous flushing of the eye, eliminating the need to constantly hold the eyelid open (see photo, p. 61). A continuous flushing of the eye with at least 500 cc of lactated Ringer's solution or normal saline is recommended. Alkali injuries require 2,000 cc followed by 50 cc per hour, or about 15 drops on the macro drip. Another simple trick is to take a nasal cannula, place the prongs over the bridge of the nose, and plug an IV line with a macro drip into the cannula and let it run.
Pain associated with eye injury can be treated with local anesthetics carried by EMS. Tetracaine or proparacaine eye drops are commonly used to numb the eye, relieve pain and facilitate flushing. Dosage is usually one to two drops and can be repeated every five to 10 minutes, depending on the severity of the pain. Each of these medications lasts approximately 20 minutes and is contraindicated for children under six years of age and for patients with known allergies to local anesthetics.
Tips for minor injuries
EMTs and paramedics are commonly asked about the treatment of a black eye. A black eye is usually a minor problem, and some simple steps can assist in its resolution. Immediately after initial injury, apply a cold pack or compress covered with a cloth. (The cloth covering will minimize the potential for damage to the thin skin of the eyelid.)
After 24-48 hours of applying intermittent cold compresses to the tissues surrounding the eye, the patient should switch to warm compresses to assist in absorption of the blood in the soft tissue.
Avoid giving aspirin or ibuprofen to patients because it may promote further bleeding into the soft tissue. The patient should lie with their head slightly elevated to assist in fluid drainage. If pain persists, the eye reddens, or hyphema or any vision abnormalities develop, immediately transport the patient to an ED.
Because specialized equipment and examination tools are often required to handle a severe eye injury, the transport destination is an important consideration. It's critical to continue assessing for any pain and deteriorating vision that may warrant expedited transport, notification to medical control or diversion to a specialty center.
Further, EMS personnel must act as good role models for eye protection. We have an opportunity to promote eye safety through injury prevention, both directly in our own workplace and by demonstration out in the field. Most EMS-related eye injuries can be prevented by wearing protective goggles or polycarbonate glasses, which have the strength to resist a .22 caliber bullet. When it's an issue of safety, we should be at the forefront.
Corneal abrasion photo courtesy VisualDXHealth, Logical Images Inc.