Dr. Le confirmed that it was the radial keratotomy that was causing the fluctuation of vision at a high altitude. He was very pleasant, professional, and he took the time needed with me, and will be happy to return each year for my exams. Thanks to the staff for working me in after having another ocular migraine. I can't remember if we discussed "why" I'm having these. If you could let me know if it's due to the radial keratotomy or something else, I'd appreciate a call....leave a message, if I don't happen to answer. Thank you again!