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Anyone Have One Pupil Larger Than The Other When They Are Feeling Particularly Poorly?

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Hi Canadagirl,

From my neuro studies, I learned that pupils should be the same size. For some with vision imbalances and habits (e.g., my left eye is stronger, used more for reading, and smaller), it may always be that way.

But for others with varying sizes, the control of pupil size is neurologic. There are many factors, but you can be pretty sure that it is an indicator of something happening in your nervous system. We learned that, other things being equal, the larger size is the one with the problem. Since the right brain is more controlling of the ANS (and the right pupil), then it might explain the difference when you are down.

I think beta blockers change the size in general, but I haven't found any association between one pupil being more affected.

That may confuse more than help, but I tried to be simple. Search "corectasia" for some more info.


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Hey! :) My right is always slightly larger than my left, I have no idea why though. I haven't really looked much when I'm feeling particularly bad vs. particularly good but I haven't noticed that it changes much depending on that. I would think that this would have something to do with how the ANS is affected, maybe that the different sides of our bodies are affected slightly differently?? I don't know, just a shot in the dark there. Maybe I'm going nuts but I've also noticed that the balance in my left leg is better than my right when I do exercises. I was just thinking that maybe there was a connection and that my left side was less affected than my right.

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Hi Canadagirl,

I get Different sized pupils quite often, especially when I'm tired. It is a sign of autonomic dysfunction.

As part of my workup I had pupilometry done. High tech camera attached to a computer flashes different intensity lights in your eyes (you sit in a dark room) they can then analyse the pupil reflex, intensity of reflex etc. Any abnormalities are due to autonomic dysfunction. My results were completely abnormal - really slow response & not enough response. My pupils on the day of the test looked the same size but when they measured them with the camera they were slightly different, which is not normal.

I frequently get blurry vision which is worse at night, my docs have said that my abnormal response to light would be contributing to this. Do you get blurry vision too?


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If you have not been checked by either a neurologist or a neuro-opthamologist, you may wish to consider it. Significant size differences in pupils can, as others here have said, can indicate neurological issues. For example, Chiari (aka Chiari malformation) can cause transient problems with unequal pupils--and can also cause changes in blood pressure and heart rate, as well as sleep apnea, etc.


similarly, spinal problems cause also produce similar symptoms:


A neurologist or neuro opthamologist can help you rule out problems that may be causing your symptoms.


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15 years ago, one of my first symptoms was that my left pupil would be larger than my right pupil. My left eye would feel dry.

Finally when I was in the hospital for a week my doctor came in one morning and said "your pupil is alot larger on the left eye."

He said the autonomic system controls the size of our pupils. I still have it all the time. I don't correlate with symptoms as I usually always feel crummy. That pupil is also more sluggish when they expose it to light.

I just chalk it up to another POTS symptom.


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If you go into a neurologist or opthalmologist with pupils of uneven size, they will definitely take you seriously.

Can you open the lid fully on the eye with the small pupil? Can you sweat on that side of the face? If not, you have Horner syndrome.

Horner syndrome is a syndrome because it is a set of symptoms and signs that tend to occur together. It can result from all sorts of different problems, including migraine.


If your pupils are too big, you will get blurry vision because depth of field gets smaller when the aperture gets larger. Same as in a camera. The bigger the opening for the light to enter, the less is in focus.

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my pupils are different sizes and have been for years, though the degree of the difference varies. after blacking out/ fainting in the past docs used to be "sure" that i had a concussion b/c they would notice this. i've also had the pupillometry testing (as part of autonomic research, at cleveland clinic) which showed all sorts of goofy things with my pupils' responses, aka their autonomic function. docs from hopkins to vanderbilt to cleveland clinic (and many places in between) have been intrigued with my pupils.

for me it's "just" part of my overall neurological issues but if you haven't discussed this with a doc, esp. a neuro, it's something they should be aware of. especially if it's new for you.

B) melissa

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