Horse eye issues

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.