Dialated pupil and light sensitivity

Occasionally (about 2 - 4 times per year) I have a problem where one of my pupils will dialate and allow too much light in. This causes problems with my vision, namely focus, and light sensitivity. There are very bright halos around any source of light and is often difficult to see. If I close the affected eye, the problem goes away. It is always the same eye. I have had this problem since I was young. The first time it happened it was accompanied by the worst headache I have ever known. Since that episode the headache is never as severe and seems to be caused by the excess light. I have been to an eye doctor during one of the episodes and everything checked out okay. The doctor told me it was obviously not an eye problem. These episodes usually last a few days and then disappear. Another issue that I notice when it occurs is that after a while, my eye actually feels sore - mostly in the back especially when I look side to side, as though my eye has been through a very vigorous workout.
Any insight or suggestions would be appreciated. Thanks.

[Ray T Oyakawa, MD]

See a neuo-ophthalmologist.  This could be Adies,  Horner's, cluster headache, etc.

Dr. O.