Uneven Pupil Dilation

Hi,
I am a 20 year old male and I have recently noticed that in dim light my right pupil dilates further than my left pupil. This is more noticeable if I am tired, and possibly after a glass of wine. I am not sure how long this has been noticeable, and looking at photos it is hard to see as I have quite dark eyes, so the pupil is hard to distinguish from the retina.

I am a medical student myself, and have recently studied the eye. I found this facinating so decided to have a good look at my own using the bathroom mirror one night (about a week ago), and this was how i first noticed the difference, if it wasnt for this I am sure I would not have noticed (and hence I have no idea if my eyes have been like this for 2 weeks, or 20 years). In bright light, there is no difference between my two pupils. I have no other symptoms (no headache etc.)

I was wondering do you think I should be concerned and if you had any advice.

Thanks,
Tom

[Michael J Kutryb, MD]

Tom, there a couple of possibilities. First the term we are talking about is anisocoria or difference in pupil size.  It is very important to determine which pupil is the abnormal. The fact that the difference is greater in dim light suggests that one pupil might have difficulty dilating normal so it is possible that the smaller pupil is the abnormal one. Of course this is not definite - just a suggestion.  Look for associated ptosis (droopy eyelid) and or a crossed or misaligned eye which could suggest a cranial nerve palsy.  A third nerve palsy could cause a dilated pupil, ptosis and an eye that has difficulty looking up, in or down.  Trauma to the eye can sometimes cause an abnormally large pupil as can certain eyedrops and drugs.  Horners' Syndrome and Adies pupil are two disorders that can cause an abnormally small pupil.  Please make an appointment with an ophthalmologist (neuro-ophthalmologist if possible) to get evaluated for possible anisocoria.

Michael Kutryb, MD

[TomE23]

so the pupil is hard to distinguish from the retina.  should read so the pupil is hard to distinguish from the iris, sorry!

[TomE23]

sorry one more thing that I am not sure if i was clear about:

I only notice the difference on some nights, even in simular lighting conditions, tonight for example there is no noticeable difference between the two pupils, but last night there was, as I mentioned in the above post if I am tired, then I am more likely to notice a difference.

Thanks
Tom

[dukey]

Are we not talking about an Afferent Pupillary Defect (APD) here? That was my interpretation based on the description.