Although the horse excellent peripheral vision to detect motion with a total visual field of nearly 350 degrees, horses have only a little more than half the visual acuity of people. Normal horses have approximately 20/33 vision. They can see well at night, but their color vision is limited to shades of blue and red.
Ophthalmic conditions of horses are most often admitted as an emergency, although in some cases the onset of ocular disease is more subtle. Dr. Kristina Vygantas is a board-certified ophthalmologist who consults with our veterinarians on ophthalmic conditions. The most common ocular condition seen in performance horses is the corneal ulcer. Some of these ulcers heal with minimal care, while others require hospitalization and placement of a sub-palpebral lavage system in order to facilitate repeated treatments throughout the day and night. Tumors of the globe or eyelids are removed with the Carbon Dioxide Laser in conjunction with follow-up chemotherapy. Foals occasionally require limited plastic surgery to correct entropion (inversion or inward turning) of the eyelids that cause ulceration of the corneal surface if left untreated. Laceration of the eyelids is yet another common injury that is usually repaired with sedation and local anesthesia on an outpatient basis.