Lisa, off the top of my head, the only thing that springs to mind is a recurrent erosion. It starts off as being a minor injury/scratch to the cornea. this heals but leaves an uneven area on the cornea. What occasionally happens then is that the patient goes to sleep and the eyelid adheres to the uneven patch on the cornea. When the eyelid is opened a few cells are ripped off the surface of the cornea again and the old injury opens up. The cornea heals quickly but the same uneven patch is still there so it happens over and over again. If this is the problem then the best thing to do is to use an ocular lubricant at night, like Vidisic Gel or Lacrilube ointment. This stops the eyelid from adhering to the cornea and allows it to heal properly. Might be worth a try.