right pupil larger than left

[cwine]

I am a 32 year old female. I am in school and a few weeks ago I was trying to sleep during the day since I had clinical at night, I put on an eye mask. When I took the eye mask off it hurt my right eye. The vision was blurry for about 5 minutes, but came back to normal, but than I noticed my right pupil dilated more than the left. It was like for about a day and then went back to normal. Now it is two weeks later and it is doing it again. I went to the ophthalmologist who looked at my eyes and said the eye itself did not look abnormal. I have been researching the internet and I am only finding ominous information. I am really scared. Are there any reasons for this that don't include tumor, anerysm, stroke, Horner's syndrome? Both pupils react to light, the dilated pupil is only evident in low light.
Thank you

[CMoore416]

My daughters pupils would look uneven and I took her in and realized that when I was looking at her in bathroom the mirror was reflecting more light on that eye making it slightly larger. Everything is fine with her

[cwine]

Is Horner's syndrome always caused by something horrific, like tumor, carotid dissection. Are there any other known causes?
I still have the unilateral pupil dilation. Like when reading about Horner's it talks about the pupils looking equal in light and unequal in low light. I do not have pitosis or any anihydrosis that I know of. I have looked back at old pictures and this is a new event.

[Ray T Oyakawa, MD]

It is probably normal.  Different pupil sizes due to a medical problem usually have other symptoms.  There some abnormalities as you have suggested.  A Horner's usually has a lid droop.  Also, you might Google Adies pupil.

Dr. O.