My Husband's Right Eye Has Been Bothering Him For Several

My husband's right eye has been bothering him for several weeks. CT's of brain and eye were WNL. An ultrasound of his carotid artery last night was WNL. The opthamologist found that he had an inflamed optic nerve but he does not know the cause yet. Fuch's dystrophy runs in my husband's family. Any guesses as to what is causing this? We are at wit's end and about to go to the Mayo Clinic. Thanks.