Well, generally speaking, if you suffer from eye blisters on the cornea, it can be painful but will usually heal within a week. For the causes, a foreign body in the cornea, a scrape or injury to the cornea, hard contact lenses, dry eye and Keratitis can be possible. There are many ways which can be used to treat it. In common, treatment options may include lubricants, ointments or eye drops. Also, you can wear an eye patch, which will reduce the pain and allow the cornea to heal. By the way, a prescription of antibiotics can prevent a serious infection. So you can just have a try. And when it occurs, it may accompany with some other symptoms, such as sensitivity to light, eye pain, and blurred vision, redness in the eye, watery eye, scratchy eye and difficulty opening the eye.