If the corneal surface of the eye is damaged, the most likely result is an ulcer, which can be very painful.Corneal ulcers are really common so it´s probably the first thing the vet will suspect if he sees a horse with suddenly red, sore, half-closed and weeping eye.It is absolutely essential that you consult a vet immediately for any problem concerning your horse's eye. any inappropriate treatment or the lack of proper treatment can lead to blindness.