Horse eye

Squinting or excessive blinking is the motion or position of the eyelid over the eye to protect against pain or irritation. In horses causes of pain or irritation to the eye include injuries, infections, and environmental irritants.

Enlarged eyes in horses can be caused by a number of different underlying conditions, including facial injury, glaucoma, infections, and cysts.

Blindness in horses is uncommon, and often difficult to identify due to their ability to adjust to gradual vision loss.

Eye discharge in horses describes any fluid leaking from the eyes.

Eye redness is a common symptom in horses that is associated with ocular conditions.

Dilated pupils (also referred to as mydriasis) describes when the hole in the middle of the iris of the eye is very large. Pupils normally change size in reaction to light changes or a particular emotional state such as anxiety or excitement. 

Equine Recurrent Uveitis (ERU), or moon blindness, is an uncommon condition affecting horses, characterized by inflammation within the eye that occurs repeatedly. ERU cycles through periods where it is active, aggressive, and painful, as well as mild phases which often show no symptoms.

Cloudy eye, also called corneal edema, describes an opacification of the eye which makes the outer surface of the eyeball appear gray, white, or blueish instead of clear.

Nystagmus is involuntary, erratic movement of the eyes. Nystagmus is a very rare symptom in horses, but when present indicates a brain injury or disorder and requires urgent medical attention.