A 41-year-old member asked:

I have unequal pupil sizes. what is the reason why?

1 doctor answer2 doctors weighed in
Dr. David Chandler
Ophthalmology 31 years experience
Many causes: An eye exam is needed to know why the pupils are unequal, as there are many causes. A slight asymmetry in pupil size might be normal for some. A dilated pupil on one side can the the sign of a serious problem (3rd nerve paralysis), as can an abnormally small pupil on one side (horner's syndrome). Adie's tonic pupil causes a large poorly reacting pupil on one side. Get an exam for a diagnosis.
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Last updated Jan 26, 2015


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