Managing the Swollen Eye in the Field (AAEP 2012)
The acutely swollen eye can present many diagnostic challenges to the field practitioner.
Photo: Lee Thomas
Equine eye injuries are ugly and usually become bigger problems if not quickly and correctly diagnosed and treated. That's why it's important your ambulatory or emergency veterinarian is properly equipped to diagnose and treat equine eye problems from the start.
At the 2012 American Association of Equine Practitioners convention, held Dec. 1-5 in Anaheim, Calif., Liz Fish, DVM, a veterinarian from Shadowrock Equine Veterinary Services, in Oneonta, N.Y., reviewed management strategies for acutely swollen eyes.
While it is possible to treat the majority of ocular emergencies in the field Fish said some require clinical referral for further treatment or surgery. The practitioner must decide when referral is the best--or only--option based on initial examination.
Have the Right Tools and Know How to Use Them
Fish explained that ambulatory veterinarians should always carry supplies for ophthalmic exams, because these types of injuries are common.
She said ophthalmic kits--including an ophthalmoscope, fluorescein and Rose Bengal dye or strips, and tetracaine or proparacaine solution--are crucial for making diagnoses. Other key supplies include those to collect corneal scrapings for cytology; tools for corneal debridement; nerve block supplies; sedatives; subpalpebral lavage and nasolacrimal duct catheter kits; and imaging equipment.
She also stressed that veterinarians should understand how to use ophthalmic tools and perform ophthalmic exams.
Acute swelling can make injuries hard to see, so the veterinarian must narrow their diagnoses down from a host of differentials. Fish offered examples, including:
- Orbit and Periorbit Problems--Trauma, neoplasia (tumors), sinusitis, orbital fractures, foreign bodies, and abscesses;
- Adnexae Problems--The adnexae are accessory structures of the eye, including the eyelids, eyelashes, conjunctiva (the membranes covering the inner surface of the eyelids), and various glands; problems that can arise in the adnexae include blepharoedema (eyelid swelling), trauma, meobomianitis (inflammation of sebaceous glands in the eyelids that lubricate the cornea), lacrimal gland (tear duct) inflammation, foreign bodies, abscesses, neoplasias, trichiasis (when facial hair or eyelashes arising from normal sites are misdirected and contact the cornea or conjunctiva);
- Cornea Problems--Ulcerative bacterial or fungal keratitis (inflammation of the cornea), corneal laceration, immune-mediated keratitis, foreign bodies, neoplasia, and chemical irritation;
- Globe Problems--Recurrent uveitis, globe penetration, blunt trauma, glaucoma, and neoplasias; and
- Retrobulbar Region Problems--Neoplasia, absceses, foreign bodies, and hematomas located behind the eyeball.
Veterinarians should begin diagnostic exams by obtaining a detailed history about the patient, Fish said. Signalment (a description of the horse's age, breed, sex, etc.), information about the onset and progression of clinical signs, and any history of previous ocular disease could help the practitioner narrow the list of differential diagnoses.
Once the practitioner collects a detailed history, he or she will move on to a physical examination. Fish said that the horse's mentation and overall comfort should be evaluated, and signs of external trauma of the animal's head should be noted. Additionally, it is important to assess the horse's cranial nerve function.
Next, Fish said, veterinarians should examine the horse's eyelids, paying special attention to swelling, eyelash position, and any wounds in the vicinity.
The next step is for the veterinarian to perform an ophthalmic examination; however she cautioned that in some cases, blepharoedema makes it impossible to open the eye. At this point, Fish recommended using ultrasound to check for pathology (tissue damage) on the eye.
"If no severe pathology is identified needing immediate attention, the eyelid swelling can be treated overnight with systemic nonsteroidal anti-inflammatory drugs (NSAIDs) therapy," she said, noting that the exam should continue the next day.
During the ophthalmic exam, the veterinarian should check all the structures within the eye with the ophthalmoscope and note any abnormalities. Next, even if the veterinarian has identified another problem with the eye, he or she should stain the eye with fluorescein and/or Rose Bengal dye or strips. For instance, the presence of corneal abrasions or ulcerations, as identified by fluorescein stain, could dictate whether or not the practitioner can use certain treatment modalities (such as steroids) safely. In these cases, steroids are usually contraindicated because they inhibit corneal healing.
Fish recommended veterinarians obtain corneal scrapings for culture and cytology in several instances, including when they suspect ulcerative keratitis or if they identify irregular corneal surface characteristics.
She also advised veterinarians to examine the eye closely for foreign bodies, such as hairs, splinters, seeds, or pieces of bedding. While some are easy to see, she said, often they are deeply embedded in the eye.
Finally, during the ophthalmic exam, Fish said imaging can help practitioners identify ocular problems not obvious during initial inspection. Specifically, ultrasonography of the eye can be helpful in cases where injury or disease prevent visualization of the inside of the eye; penetrating injuries; orbital fractures; and others. Radiography, she said, is indicated when fractures, neoplasia, sinusitis, or foreign bodies are suspected.
Fish also discussed the benefits of using digital photography to monitor healing, enhance medical records, and allow for conference with colleagues.
Initial Treatment Options
Fish listed several medications that field practitioners should carry to provide initial treatment for acutely swollen eyes. These include:
- Antibiotic ophthalmic ointments and solutions;
- Antifungal ophthalmic ointments and solutions;
- Systemic NSAIDs;
- Atropine ophthalmic ointment;
- Hydrocortisone or dexamethasone ophthalmic ointments; and
- Hypertonic saline ophthalmic ointments.
Use and prescription of medications depend on the specific eye condition.
Often horse owners must administer eye medications multiple times a day on regular intervals, as advised by their veterinarian. Fish discussed the use of subpalpebral (underneath the eyelid) lavage catheters to help ease the medication administration process for horse owners. These lavage systems involve flexible tubing, which is passed through the upper or lower eyelid and stitched into place, with medication administered via the other end of the tube. She also mentioned infusion disc antibiotic delivery systems--a relatively new technology that allows time-release administration of antibiotics to the eye--as an alternative to traditional medication administration.
"The acutely swollen eye can present many diagnostic challenges to the field practitioner, but following a stepwise approach to evaluation, and using additional diagnostics, the practitioner can arrive at a diagnosis on the farm in the majority of cases," Fish concluded.
About the Author
Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.