Equine recurrent uveitis (ERU), also known as periodic ophthalmia or moon blindness, is one of the most common causes of blindness in horses. Classic treatment of ERU includes mydriatics, corticosteroids and nonsteroidal anti-inflammatory drugs. Despite vigorous topical and systemic treatment, however, in many cases, the prognosis for preserving vision remains poor.
Signs of Equine Recurrent Uveitis
The signs of this disease are acute pain with the eye closed, discharge, and unwillingness to expose the eye to light. The cornea is cloudy. The eyelids remain tightly shut and tears often run down the cheeks. The conjunctiva and iris are red and inflamed. Recurent attacks diminish the sight until complete blindness results. Despite extensive clinical research, the causes of equine recurrent uveitis (ERU) are still unknown. In general, the diseases is thought to be an exaggerated response of the immune system to a wide range of organisms, including leptospires bacteria and and Onchocerca cervicalis parasites.
Diagnosis is made based on detailed examination of the eye. Long and vigorous treatment is necessary to control the inflammation. Antibiotic treatment is used if a bacterial cause is suspected. Corticosteroids and atropine applied to the eye are also essential. New surgical techniques for ERU have been recently developed giving horses with equine recurrent uveitis a chance of a cure, and the possibility of maintaining their eyesight. The surgery involves making an incision through the sclera and removing the infected base where the organisms are. Then, antibiotics are flushed into that tissue to kill any residual organisms. Any clouded up and inflammatory debris is also removed.
Researchers at the ophthalmology department at North Carolina State UniversityWe have developed a drug delivery device (a micro-implant) for treating uveitis. The implant, which delivers a constant amount of cyclosporine (an immunosuppressive agent) within the eye, is made at NCSU and currently is being distributed free of charge to ophthalmologists who request one.
Proper treatment improves the course of the disease, especially if started early. However, the disease is often complicated by secondary catarcts and detachment of retina usually result in irreversible loss of vision. Conventional treatment does not prevent recurrence and horses that have had one attack will almost invariably have another at unpredictable intervals. Some eye problems are more preventable than others. Professor Brian Gilger, DVM, MS, Dipl. ACVO, Chief of the Ophthalmology Service, the ophthalmology department at North Carolina State University recommends that horse owners minimize the risk of eye trauma and infection by using a fly mask, and feeding hay on the ground, not from nets, bags, or elevated mangers. "They're horrible about causing eye trauma," he warns.