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my 16 year old daughter has one of her pupils noticably smaller / larger than the other. possible causes?


The most common cause is physiologic anisocoria – which means that her pupils simply are different sizes. In this condition each pupil will react to light the same way meaning that the size difference stays the same in light and dark conditions.

Another condition could be Horner’s syndrome which is a problem with the sympathetic nervous system. With this condition the difference in the size of the pupils will increase in dim light conditions. The affected pupil will be smaller in size.

The last condition could be Adie’s tonic pupil which is a problem with the parasympathetic nervous system. This pupil is minimally reactive to light and the patient may complain of blurred near vision.

If you have any concerns she should be evaluated by an eye care professional.

For more information:

Go to the Eye and Vision Care health topic.