my shih tzu had an eye ulcer last fall and he recently went in fo another eye ulcer. the vet checked the old ulcer and showed me how it had scar tissue and is still reactive. does this affect their vision? i notice when he sees a squirell far away he wants to go after it. i caught the second ulcer early so it is just the size of a pin point. the first one i didn't realize the signs and it got bad and had to have his eye sewn shut to heal. if you ever see your dog rubbing his eye on the ground, blinking a lot, and squinting, get your dog to the vet immediately.