Why are my pupils different sizes?

[Ksilver2]

Hi, I am a 24 year old male who has noticed unequal pupil size for the last 4 months.
To be more specific my right pupil is more constricted than my left pupil.  The difference in size is more noticeable in dim light but still recognizable in bright light.  Sometimes the difference in dim light can be somewhere around 2mm.  According to multiple doctors, both eyes respond normally to light.  I also had an ophthalmologist tell me my eyes are healthy and I have had a normal CT, MRI, and chest x-ray.  Along with that I have had multiple ekgs, blood tests, and neurological exams.  I do not have any other neurological symptoms currently but for a while I had ocular migraine symptoms that have now gone.  This condition has caused severe anxiety to the point where I can't believe there isn't something terribly wrong with me.  I have been on lexapro for a week for that.
My neurologist is too busy to talk to me so I'm here instead.  The reason I'm here is because of how different my pupils can get, can essential anisocoria show differences >1mm?
Also I have not had any serious trauma to my head or eye recently. My parents also think they remember bringing this up to my doctor as a child but it was a very long time ago.
If you have any questions feel free to ask them.
Thanks!

[JohnHaganMD]

You have had an extensive work up that should have shown up the serious causes of acquired aneisocoria.  Unless something changes and I would stop worrying and move on.   Many cases are begin.  Some of the most common causes:  sudden awareness of longstanding unequal pupil (at least 10% of people have unequal pupils that they were born with)  Addie's tonic pupil is a common cause without serious cause, Some cases of acquired Horner's Syndrome are without serious cause.   Most physicians would feel you have had enough tests and tell you to stop worrying unless something new or different develops.