Ophthalmology

Equine recurrent uveitis, also known as moon blindness, is the leading cause of blindness in horses worldwide, affecting an estimated 2–25% of the global equine population. It involves repeated bouts of intraocular inflammation that progressively damage the lens, vitreous, and retina, with Appaloosas at up to eight times higher genetic risk than other breeds.

Diagnosis relies on fluorescein staining and slit-lamp or penlight examination. Treatment depends on depth and microbial involvement and may include topical antimicrobials, atropine, serum or plasma drops, and in deep or melting ulcers, surgical intervention such as conjunctival grafting.

A complete exam includes menace response, pupillary light reflex, direct and consensual testing, fluorescein staining, tonometry, and evaluation of the anterior chamber, lens, and fundus. Sedation and nerve blocks may be needed for a full assessment in fractious or painful horses.

Suprachoroidal cyclosporine implants are considered in horses with recurrent uveitis that is poorly controlled with topical therapy alone. The sustained-release device delivers localized immunosuppression for approximately three years and has been shown to reduce the frequency and severity of flare-ups.

Evidence of prior uveitis, cataracts, corneal scarring, squamous cell carcinoma risk, and fundic abnormalities are key concerns. A documented ophthalmic exam establishes a baseline and helps buyers understand potential long-term risks to vision and performance.

Treatment options include surgical excision, cryotherapy, radiation therapy, and topical chemotherapy, selected based on tumor size, location, and stage. Early detection improves outcomes and may preserve the globe in cases involving the eyelid, third eyelid, or limbus.