Eye Injuries

Equine eye injuries require immediate veterinary attention. Even minor injuries may develop complications, including blindness, and it’s best to begin treatment as soon as possible.

Common injuries and diseases include corneal abrasion and ulcers, keratitis, conjunctivitis (tissue inflammation around the eye), uveitis (swelling and irritation of the middle layer of the eye), habronema (persistent conjunctivitis associated with eye worms), and keratoconjunctivitis sicca (dry eye syndrome – less tears are formed).

Signs of injury or disease include swelling, redness, or an abnormal amount of discharge. The eye may have a bluish-white tint or appear cloudy. Blood vessels will be seen across the surface of the eye, pulling this cloud with them and providing blood to repair the injury.

Your vet will utilize an ophthalmoscope and fluorescein dyes to diagnose any eye problems. Fluorescin will dye or stain the eye green to highlight injury or detect foreign bodies. It is placed under the lid via a slip of paper containing the stain or with a syringe. Stain will only be taken up when there is a break in the tissue and will differentiate which layer has been affected.

Treatment is based on how the stain is dispersed (i.e. one line, several small spots). If stain is present, the objective then becomes preventing infection in the surface wound.

If there is no stain uptake, treat the horse to prevent infection and lessen discomfort, clear up redness of conjunctivitis, and lubricate the eye to prevent irritation. Ophthalmologic triple antibiotic is commonly used. It is important you do not use an antibiotic made with steroids in place of the triple antibiotic ointment, as steroids can restrict blood flow to the eye, causing a slow healing process and can do more harm than good to the eye.

Discomfort may be caused by eye muscle contraction to the lens. A secondary eye medication may be required to relax these muscles.

Eye Infections

Eye infections, like all eye injuries, need to be treated carefully. If the infection is bad enough, the eye structure can actually erode and cause it to collapse.

Treat for an infection if you notice a cut, torn, or swollen eyelid, obvious damage to the eye, a white film is present, red or inflamed eye or tissue can be seen, tears running down the face, large amounts of eye discharge, eyelid tumors, or the eyelids of a foal are turned under.

If an injury or infection is suspected, flush the eye with a saline solution (contact lens solution will work), put a fly mask on the horse and keep him in a dim stall until your vet can address the situation.

Corneal Ulcers

Corneal Ulcers are disruptions of the corneal epithelium (outer layer of cells). They begin with corneal trauma, resulting in the removal of corneal epithelial cells, exposure of stroma (connective tissue), and can result with bacterial or fungal organisms invading the stroma. These ulcers can be directly seeded by branches brushing the eye.

Fungal Ulcers

Fungi are found in hay, grass, shavings, straw and dust. They can live with bacteria on the surface of the cornea and conjunctiva. Fungi cause the severe corneal disease keratomycosis (in which you will see ulcers, abscesses and iris prolapses) following corneal trauma or inappropriate treatment for corneal ulcers.

Fungal ulcers are commonly seen in warm, humid regions.

Keratomycosis

Signs of keratomycosis include corneal swelling, droopy upper eyelids, small pupils, squinting, and increased tearing. Diagnosis is based on a cellular exam of a corneal scraping, culturing the corneal lesion or a surgical biopsy. A downside to diagnosis of keratomycosis is that if the fungus has worked its way deep into the cornea, a false negative result can be seen.

Uveitis, or iridocyclitis (inflammation of the iris and cilary body) are always found too.

As few as fifty percent of eyes with keratomycosis may retain vision. Half of keratomycosis-infected eyes may become blind or need to be removed. The high rate of failure may be due to a lack of aggressive treatment early on. If discovered and treated early, there is a positive probability for both vision and eye survival – nearly 90%, but treatment will be prolonged, expensive and corneal scarring may occur.

Your vet will recommend a plan to treat the fungi as well as the inflammation. This may require an extended period of treatment as anti-fungals tend to slow growth rather than kill fungus quickly. Anti-fungals include miconazole, itraconazole, silvadine, and fluconazole. Antibiotics will be recommended because bacterial infection commonly runs concurrent with fungal infections.

Treatment of Eye Injury/Disease

Most common, a therapy of triple antibiotic eye ointment will be recommended. However, topical antibiotics are not always the answer, as they can suppress certain bacterial strains and allow multiplication of resistant organisms.

Acetylcysteine is used as a last resort to decrease enzyme activity in the tears of horses with melting corneal ulcers (due to psuedomanas or matrix mecalloproteinase). Drawbacks to this medication include eye irritation, costs (it is quite expensive), a foul odor and the need for refrigeration.

There also is a therapy involving use of blood serum enzymes to speed corneal healing.

Your vet may suggest you treat the horse with atropine sulfate drops to dilate the pupil and Banamine to ease eye pain associated with ulcers.

As previously mentioned, be aware that use of ophthalmologic steroids can worsen eye diseases, suppress immune protection so microbes can more easily cause disease and predispose the cornea to fungal infection, and decrease effectiveness of antifungal agents, thus furthering the infections.

Surgery may be necessary if the ulcers are deep, and do not respond (or worsen) during treatment. Up to 50% of horses might require a combination of traditional treatment along with a conjunctival graft or a full-thickness corneal transplantation (taken from a donor horse).

For major eye injuries, medication is administered via an eye pump. This pump is attached to tubing which is threaded directly to the eye. A disk containing several medications continuously delivers treatment to the affected area. These pumps are an expensive but necessary therapy.

Use any medications prescribed for the full course, even if the horse appears to be more comfortable. Keep the horse in a dust free, dim environment and cover any sharp edges or nails he may be tempted to scratch on. Always be aware of his blind side when working around him.

Preventing and Handling Eye Injuries

Keep in mind that eye injuries and disease are not uncommon. Owners should take precautions to keep the horse in as safe an environment possible, free of protruding nails and sharp edges. The area should be as dust free as possible.

Contact your vet immediately if you discover or suspect any injury to the eye. If the eye is lacerated, clean with a saline solution of ¼ teaspoon salt to 1 cup of lukewarm water (contact lens solution will work also). If a foreign object is in the eye try to remove it – easy if it is in the eyelid but if the eyeball itself is involved, do not attempt it. Keep your horse quiet until the vet can arrive.

Keep the horse’s face covered with a fly mask during the summer months and avoid bright light. Follow all courses of medication as directed and remember, the horse may have some obscured vision and be spookier than usual.

With proper care, minor eye injuries may heal in as little as one week – much faster than skin injuries.