Some mild difference in pupil size can be normal, up to about 0.5mm, and is called 'anisocoria'
Without other neurological signs or symptoms, there is usually no underlying abnoramlity.
If the pupil difference changes, or there is for instance worsening headache, double vision, etc then it hsould be evaluated
Brain tumors or nay other masses cause unequealpupuls by pressing on the cranial nerves - in this case usually there are other signs like impairment of eye movement. An MRI would be low yield to show an abnormality then but may serve to assure that it is normal, CT brain cannot ruleout out a tumor.
Good luck
I dont know. I'm almost afraid to get the MRI.
As far as having migranes before, the only time I knew I had one was last year and it lasted for a month before I got migrane meds from the doc. I dont remember my pupils being odd.
Had what I think was a migrane last night, a really sharp pain on the right side of my head then followed a bad headache. Same spot everytime this happens. I am so scared :( :( :(
I know it's scary to get an MRI, but since migraines can only be diagnosed by ruling out all other possible causes, you really need to let your doctors run the appropriate tests. But I truly don't think you need to be too worried; you have a definite history of migraines, and you could at times be having migraine activity in your brain without actually having headaches (such activity is called "migraine equivalents"). I had migraines 30+ years ago as a child/young teenager, and like you, in the past my pupils were fine. Ironically, I started noticing my pupils were frequently a different size this past September, but I really haven't had an all-out migraine headache in several years. I, too, got very scared, particularly as I'd been having periodic dizzy spells, light sensitivity, and sound disturbances (i.e., sometimes things either seem too loud or too soft); but now I've learned that all of these are also signs of "migraine equivalents." So you really can't diagnose yourself just by watching your pupils. I do hope you'll get the MRI; I really think it will ease your mind.
Just to ease your mind: I've been having the same sort of size difference in my pupils, and I recently had a completely normal brain MRI. Both my neurologist and neuro-ophthalmologist believe the pupil abnormality in my case is migraine-related (and neither doctor is at all alarmed). So although you should probably have the MRI to be sure, if you've had migraine symptoms in the past it seems likely/possible that migraine activity in your brain would explain your pupil difference (as a brain tumor would likely be causing more dramatic symptoms).