Sight loss can be due to corneal ulcers or other eye diseases. To determine if your horse has lost its sight, look for what we call the “dazzle response”: Shine a bright light into the eye and watch for a slight closing of the upper eyelid. Essentially the horse is letting you know they sense the light. Care must be taken to avoid touching the eyelids so a little distance from the eye is important and it can require an intensely bright light.