Glaucoma (border collie type) is an inherited eye disease affecting dogs. Affected dogs display malformations in an area of the eye known as the iridocorneal angle often resulting in increased eye pressure in both eyes. As the pressure in the eyes increases, they become painful. Signs of pain include excessive blinking, tearing and redness. If left untreated, increased pressure in the eyeball leads to enlargement, optic nerve damage, and the gradual loss of vision.