My daughter's young SO has it and he is sick as a dog. They have done an MRI and are talking about all sorts of scary things causing it. He can't barely lift his head without tons of pain. I never heard of it before, but 10% of those who have it go blind and it can be caused by tumors or cancer or systemic disorders. He has been off work for over a week and won't be able to go back anytime soon...I really like him and am quite concerned as is my daughter... Thank you.