List three classic signs of glaucoma in the horse.

• A. Elevated intraocular pressure, corneal edema, and a dilated, nonresponsive pupil
• B. Conjunctival hyperemia, mucopurulent discharge, and minimal aqueous flare
• C. Hyphema, retinal detachment, and cataract
• D. Decreased intraocular pressure, shallow anterior chamber, and episcleritis

Answer: (A)

Glaucoma in the horse is driven by a rise in intraocular pressure from impaired outflow of aqueous humor. That elevated pressure leads to corneal edema, making the cornea appear cloudy or blue-tinged as the stroma swells. The iris and pupil are also affected by the high pressure, resulting in a dilated pupil that is slow or nonresponsive to light. These three signs—high intraocular pressure, corneal edema, and a dilated, nonresponsive pupil—are classic indicators of glaucoma in horses. The other options describe findings more typical of inflammation or other ocular diseases (such as conjunctival inflammation, discharge, hyphema, retinal issues, or a shallow chamber with low pressure), rather than glaucoma.