Which condition is listed as a cause of central-origin blindness?

• A. CNS disease
• B. Trauma
• C. Hyphema
• D. Glaucoma

Answer: (A)

Central-origin blindness refers to loss of vision due to pathology within the brain and the central visual pathways (from the optic nerve onward to the visual cortex), not the eye itself. When the visual system is damaged at the CNS level, the horse can be blind even if the ocular exam looks normal. Among the options, CNS disease directly affects these central pathways, making it the best fit for central-origin blindness. Hyphema is bleeding into the anterior chamber and represents an ocular, not central, problem. Glaucoma damages the retina and optic nerve within the eye due to elevated intraocular pressure, also an ocular origin. Trauma can cause blindness, but unless it specifically injures the brain or optic pathways, it’s not the central-origin mechanism being tested here.