Introduction

In the United States (USA), approximately 7.5% of people suffer eye injuries at some point in their lifetime.[1] Of those, 6.1% are left visually impaired, 6.9% are partially blind, and 0.6% are completely blind. This amounts to roughly 1.5 million, 1.7 million, and 147,000 individuals with permanent visual impairment, partial blindness, and complete blindness, respectively. Recent estimates report 2 to 2.4 million cases of ocular trauma each year, with hospitalization occurring in about 22% of cases.[2] 

The elderly population has the highest incidence of hospitalization for ophthalmic trauma.[2] Males are predominantly injured, and the cause of injury varies with age. Elderly persons most commonly suffer from falls, whereas adolescents and younger adults are more often injured in motor vehicle collisions and assaults. Children experience increased accidental and sports-related injuries. Eye trauma is one of the most common and preventable etiologies of visual impairment and blindness; despite increased emphasis on protective eyewear in recent decades, prevalence is expected to increase with the aging population.[2][3] 

Lasting visual impairment or vision loss is detrimental to one's activities of daily living (e.g., finding items, driving, etc.) and quality of life, so it is crucial to be well-prepared not just in injury prevention but also in its management.[4]

Ocular anatomy includes the periorbital tissues, globe, cornea, iris, ciliary body, lens, vitreous humor, retina, choroid, and optic nerve. The majority of traumatic ophthalmic injuries comprise hemorrhages, lacerations, perforations, foreign bodies, fractures, and burns of these structures, as well as their sequela.

Some are readily apparent on examination; others require advanced testing or imaging to be identified. Many eye injuries, even minor ones, will warrant some treatment, ranging from topical medications to invasive surgical intervention. When an injury occurs, it is essential to prevent further damage and obtain a timely assessment so that appropriate treatment is not delayed, as this may negatively and indelibly affect visual outcomes.[5] This begins with the first point of contact with medical personnel, often Emergency Medical Services (EMS).

EMS may be dispatched to a wide range from isolated eye trauma to severe trauma with multiple injuries. During the latter, after any life threats have been addressed, it is essential to recognize an eye injury during the initial assessment, especially those which are threats to vision, so prompt action is taken by EMS and the receiving facility to provide the best outcomes for patients. A focus will be directed to open globe injury, orbital compartment syndrome, chemical injury, and corneal foreign body, as patients with these diagnoses, in particular, benefit the most from immediate awareness and action in the field.

History and Physical Examination

Essential historical information to gather includes location and timing of the injury, mechanism, and--in the instance of penetrating trauma or foreign body--the material.[6] There are various eye-specific symptoms, such as vision change, double vision, floaters or shiners, discharge, photosensitivity, foreign body sensation, etc. Pertinent past medical history includes baseline visual acuity, contact lens use, and previous ophthalmological surgeries. A systematic examination ensures a complete assessment when possible.

This includes visual acuity and field testing, pupillary and extraocular muscle (EOM) exams, and, finally, visual inspection. The use of a Snellen eye chart may be excessive for the prehospital setting and deferred for the ED; however, a gross assessment of visual acuity can be performed by checking for the perception of light, detecting hand motion, and ability to count fingers and/or read print.[7] Peripheral vision of all four quadrants must also be checked.

Pupillary examination entails direct reactivity to light and the swinging light test, which evaluates for a relative afferent pupillary defect (rAPD). In rAPD, When light is repeatedly swung from one eye to the other, the injured eye will constrict appropriately when the light is pointed at the contralateral eye but dilate when the light swings directly to it. In the setting of trauma, this can be suggestive of optic nerve injury, retinal detachment, or vitreous hemorrhage.

Extraocular muscle assessment is done by having the patient track in the six cardinal positions of gaze (i.e., right, left, and all four corners). Failure to do so with one eye or the presence of diplopia is suspicious for EOM injury.[8] Most notably, failure of the eye to track superiorly is concerning for orbital floor fracture with EOM entrapment--an urgent surgical matter.

Regarding visual inspection, an external-to-internal process is a simple and easy approach to be thorough and avoid missing an injury. Begin with the periorbital soft tissue and eyelid before observing the general position of the globe. Anterior, posterior, or inferior displacement (exophthalmos, enophthalmos, and hypoglobus, respectively) raises concern for major injuries such as orbital fracture, retrobulbar hematoma, and optic neuropathy.

Inspection of the cornea, sclera, and iris may be performed next and may reveal a foreign body, penetrating eye injury, and traumatic hyphema (collection of blood in the anterior chamber), to name a few. Scleral or deep corneal lacerations, iris or pupillary abnormalities, or prolapse of the iris or uvea through a corneal laceration must prompt concern for open globe injury and management as further described below.[9] Otherwise, a thorough investigation of every section of the eye and underside of the eyelids may be done to complete the assessment.

Issues of Concern

Open Globe Injury (OGI)

Open globe injuries encompass ruptures, lacerations, penetrations, perforations, and intraocular foreign bodies, per the Birmingham Eye Trauma Terminology System (BETTS) developed by the Ocular Trauma Classification Group.[10] 

Both blunt and penetrating trauma can cause open globe injury. In addition to vision loss, there is a risk of endophthalmitis (deep eye infection), chronic pain, and sympathetic ophthalmia (autoimmune response leading to eventual vision loss in the uninjured eye).[6] Individuals with OGI require an emergent ophthalmological assessment to evaluate injuries and surgically repair them promptly. 

The mechanism of a patient's injury may raise suspicion for open globe injury (e.g., sudden eye pain and vision loss during unprotected welding). However, it is not always so apparent. For example, the elderly suffer from OGI, most commonly from ground-level falls.[9]

It is important not to make it worse, so any time an eye injury is present, one must proceed with caution on initial evaluation. No pressure should be applied to the eye, so it must be visualized very gently. When open globe injury is suspected, immediate steps must be taken to protect the eye from further damage.

The application of an eye shield comes first and foremost. If an eye shield is unavailable, taping a cup over the eye may be a suitable replacement. If a penetrating body is still present, the shield must work around it. Administering antiemetics and analgesia and elevating the head of the bed may prevent increased intraocular pressure (IOP) and extrusion of intraocular contents. In patients who require intubation, avoidance of ketamine and succinylcholine is preferred, as there is some evidence that these raise IOP.[9] Further examination and interventions should be deferred.

Chemical Injury

Chemical injuries to the eye can be very serious and vary with the offending agent, amount, and exposure duration. They are classified as acidic or alkaline burns, with the latter having the greatest potential for harm. Coagulation necrosis occurs with acid burns (e.g., acetic acid, citric acid). Proteins are denatured and eschar forms; this process helps to prevent further advancement of the offending chemical, thus, limiting the damage done.[11] 

However, liquefactive necrosis occurs with alkali burns (e.g., bleach, ammonia). The reaction of the chemical with cellular enzymes results in liquefication of the tissue and allows for deeper penetration of the agent and continued destruction until it is washed out.[12] The eye structures are at high risk of permanent destruction, including the limbal stem cells, which normally facilitate healing.

The amount of time that lapses between the initial exposure and irrigation significantly impacts the prognosis.[13] Therefore, it is critical to perform large-volume irrigation with at least 1 liter of normal saline or Ringer's lactate solution immediately.[12] 

Discontinuation is guided by the pH of a person's tears, typically with eye pH paper strips. Gently apply the strip to the conjunctival fornix--the fold where the inner eyelid and globe meet--and compare the color to the reference values. Unfortunately, pH paper strips may not be on hand in the field. Urine dipsticks are a potential substitute worth noting, as these may be more readily available in medical offices, nursing homes, etc. Simply cut the dipstick strip so the pH square is at the end and apply this to the conjunctival fornix. Remember that urine dipsticks do not cover the full 1 to 14 pH range but rather 5 to 9. The goal is to irrigate until a physiologic pH of 7.0 to 7.4 is achieved.

An eyewash station at the scene is ideal for immediate use, but this may not be an option depending on the setting or the patient's condition. The Morgan lens is a plastic device designed to directly and continuously irrigate the eye.[14] It is applied similarly to a contact lens and has a short tube that connects to intravenous (IV) tubing for continuous flow.

Patients can lay supine and close their eyes while this is running, making it practical for use during transport. Alternatively, if a Morgan lens is not at one's disposal, a nasal cannula can similarly be incorporated in a less invasive manner. Connect it to the end of the IV tubing, position the nasal prongs over the bridge of the nose while supine, and begin irrigation. Place several towels and/or a basin at the head to absorb and collect the solution running from the eye(s). Once physiologic pH is reached, further examination can be performed.

Orbital Compartment Syndrome (OCS)

An acute rise in intraorbital pressure can lead to central retinal artery occlusion and resultant optic nerve ischemia.[15][16] Irreversible vision loss may occur within 90 minutes, so prompt recognition and action are paramount. In the setting of trauma, OCS is frequently associated with orbital fracture and retrobulbar hematoma, both of which are not evident on the exam.[17]

Findings suggestive of OCS include decreased visual acuity, proptosis, limited extraocular muscle movement, and relative afferent pupillary defect. Intraocular pressure greater than 40 mmHg is an objective measure of OCS. However, OCS is a clinical diagnosis. Emergent lateral canthotomy and cantholysis should be performed within 2 hours by an emergency physician or ophthalmologist to have the best chance of preserving vision.[18] 

Exposure of the lateral canthal tendon and incision of the inferior crus relieves the intraocular pressure.[19] If this is insufficient, cantholysis is repeated with the superior crus for further relief.

Corneal Foreign Body

The cornea is the clear, protective outer layer of the eye and, therefore, the most often injured. Corneal abrasions are a less severe but more common form of eye injury for EMS personnel to be familiar with. Scratches to the cornea are very painful and may be due to a foreign body, contact lens, or other trauma. Patients frequently have photophobia, increased tearing, and the sensation of a retained foreign body, whether one is present or not.[20] 

Examining the eye can be very difficult and limited without analgesia. Corneal abrasions themselves do not require immediate action; however, a retained foreign body can cause further damage and later become embedded.

If there is any suspicion of open globe injury, protect the eye as directed above. If there is no evidence of open globe injury, one may inspect the eye for foreign bodies. If a contact lens is present, remove it. A complete, thorough examination of every quadrant of the eye must be performed, even after finding a foreign body, as there can be more than one. They may be seen on the cornea or hidden underneath the eyelids. Evert the eyelid by placing a cotton-tipped swab against the outer lid and pulling the lid back over it, exposing the underside.[21] Do the same with the opposite eyelid.

When a foreign body is identified, a stepwise approach can be taken to attempt removal. Irrigation (as explained above) may successfully wash away debris without causing further injury. It is important to note, however, that a Morgan lens is contraindicated in this setting because its position directly against the eye can potentially exacerbate the abrasion elicited by the foreign body. If irrigation is unsuccessful, the next step is to utilize a moist gauze or cotton swab gently.[21] 

Take care not to cause an additional abrasion. This requires a steady hand and patience and should not be performed otherwise (e.g., in an ambulance). It may be more reasonable to transport the patient to the emergency department, where facilities and available equipment will allow for an easier, safer procedure. They may ultimately use a 27-gauge needle with a slit lamp to remove the foreign body if all else fails. In addition to foreign body removal, they can administer topical analgesia and utilize a fluorescein stain to perform an in-depth ophthalmic exam.

In the absence of major injuries, patients are typically discharged home with ophthalmic antibiotics. Contact lens wearers require anti-pseudomonal coverage with fluoroquinolones or aminoglycosides (e.g., ciprofloxacin, gentamycin); otherwise, erythromycin ophthalmic is the treatment of choice.[22]

Clinical Significance

Several simple but important actions can be undertaken by prehospital personnel to manage ocular trauma. Harm from chemicals may be effectively stopped with early and extensive irrigation. Corneal foreign bodies and contact lenses may be removed when contraindications are absent. In instances of potentially elevated intraocular pressure or open globe injury, the head of the bed may be elevated at least 30 degrees to avoid an unnecessary increase in IOP or extrusion of intraocular contents, respectively.

In the case of a low-grade traumatic hyphema, this also may keep blood out of the field of vision. Treating pain and nausea may further prevent IOP elevation. And finally, shielding, mainly when there is a concern for open globe injury, protects the eye from further insult. Timely transference to the emergency department for a comprehensive evaluation and possible consultation with an ophthalmologist, especially in the case of orbital compartment syndrome, is key to optimal patient outcomes.