[Fast]

My left pupil has been noticeably larger than my right pupil for about a week now; this has not affected my vision. It will still dilate when I shine light directly into it. I've had no recent head injuries or trauma of any kind. As of last night, I've felt pressure and mild pain in my left eye-"achy pressure"is the only way to describe it.The only medication I take is ultram 50mg 1-3 times per day, as needed for a preexisting condition, which I have taken for almost a year now and has caused no previous problems.What could be the cause of this? What should I look out for?

[Shine Eyed Mr. Zen]

Not to scare you, but I've read somewhere that a brain tumor could be the cause.You should make an appointment with your doctor.

[Hope]

you really need to consult with your doctor on this. any time you have a noticeable change in your eyes (pupils) like this it could mean many things including a tumor behind the eye.If you get it checked out early, most things are treatable - but if you wait - you may not like the outcome - Please seek medical advise on this!