Ophthalmology in the Wilderness (Part 2)

The Approach to the Eye Complaint

The Wilderness Medicine Society’s practical guidelines for treatment of eye injuries and illnesses has a great approach to the eye complaint, and I have found it to be the most optimal way to break down the differential diagnosis and guide the rest of the exam. This method divides eye pathology into three groups: the white eye, the red eye, and eye trauma.

The White Eye

Also known as the “quiet eye”, the white eye generally refers to painless vision loss. Peri-orbital pathology is included in this section, as there is no inflammation of the actual eye structures. Painless vision loss is an ominous symptom, and is often caused by a vision threatening process.  The differential includes central retinal artery occlusion, central retinal vein occlusion, retinal detachment, vitreous detachment, vitreous hemorrhage, and optic neuritis. Without the ability to perform fundoscopy, it is impossible to differentiate the actual pathology, although ultrasound can be extremely helpful. A RAPD (see part 1) can be present, but is not specific for a specific diagnosis. For suspected retinal artery occlusion, simple maneuvers such as globe massage, carbon dioxide re-rebreathing, and high flow oxygen, if available, can be attempted. Ultimately, all painless vision loss should be emergently evacuated as determining the etiology is extremely difficult in the austere environment.

Causes of peri-orbital inflammation vary from benign skin and soft tissue pathologies to vision and life threatening infections. Knowing how to distinguish between them is essential. Peri-orbital etiologies include pre-septal cellulitis and dacrocystitis. These are both simple infectious processes that are easily treated with antibiotics and symptomatic management. Hordeola and chalazea are acute inflammatory processes of the eyelids and can be treated symptomatically with warm compresses and lid hygiene. Orbital cellulitis, however, is an infectious process that involves the structures of the orbit, and can progress to cavernous sinus or central nervous system infections. The presence of visual disturbances, painful limitations in extra ocular motion, proptosis, increased intra ocular pressure, or systemic signs of infection such as a fever clinically distinguish it from an extra-orbital process. These patients require IV antibiotics and emergent evacuation.

The Red Eye

There are multiple causes of a non-traumatic red, painful eye. A recommended approach that I find useful both in the austere environment and the clinical setting is to use simple testing to divide the differential into distinct categories. After performing a basic eye exam, the next step is to apply a topical anesthetic such as tetracaine and observe for improvement in symptoms. Lack of improvement indicates that the pathology is likely not isolated to the surface of the eye. This differential includes iritis/uveitis, scleritis, and acute angle closure glaucoma, and requires emergent evacuation. For those with improvement after the tetracaine, the fluorescein testing is performed. Etiologies such as conjunctivitis, blepharitis, and foreign bodies are generally improved with a topical anesthetic but do not have fluorescein uptake. If there is uptake, corneal erosion, corneal ulcer, UV keratitis, and herpes simplex keratitis should be considered. Of these, generally only herpes keratitis requires emergent evacuation, however in certain settings, urgent evacuation should be considered if the proper ophthalmologic evaluation and treatment are not available.

Traumatic Eye Injuries

Orbital and ocular trauma can range from mild to vision threatening, and any direct trauma should be thoroughly evaluated for emergent conditions. Retro orbital hematoma, globe rupture, complicated orbital fractures, complex lid lacerations, hyphema, or chemical injuries require emergent evacuation. Field treatment focuses on symptom control, preventing further damage, administration of parenteral antibiotics or steroids. If it is within the provider’s scope of practice, a clinically suspected retro orbital hematoma should have a lateral canthotomy performed. Orbital impalement objects should be stabilized and left in place. Often times covering both eyes will prevent eye movement and further damage. For any chemical injury, copious irrigation should be performed. All of these patients should be emergently evacuated for definitive care.

Simple corneal abrasions, keratitis, or corneal frostbite can be managed non-emergently pending the ability to continue safely in the current environment. Topical antibiotics can help prevent infection, and the patients should be frequently re-evaluated for any signs of disease progression.

In summary, it is important to know how to perform an eye exam and evaluate for a vision threatening process. Breaking the differential down into the white eye, the red eye, and eye trauma can help to guide treatment and evacuation priorities. Basic eye exam equipment and medications should be considered when putting together a medical kit for an expedition. Any vision threatening pathology should be evacuated emergently, and in non-emergent situations, consideration should be given to the limitations of decreased visual acuity or monocular vision. The Wilderness Medical Society Practice Guidelines for Treatment of Eye Injuries and Illnesses in the Wilderness is a great resource for wilderness ophthalmology and give a thorough overview and also goes into treatment recommendations for the conditions listed above. As always, comments and questions are welcome.