Some Causes and Features of Unequal Pupils
Cause | Common Features* |
|---|---|
Adie (tonic) pupil (a pupil that does not constrict normally in response to light) | One or both pupils are too wide, do not fully constrict in response to light, and widen slowly after being constricted by light No other symptoms |
Argyll Robertson pupil | Pupil that constricts better to accommodation (when a doctor's finger moves towards the eye) than to light History of syphilis |
Birth defects of the iris | Features that are present lifelong Usually other birth defects |
In people who use or have been exposed to these substances Sometimes difficulty focusing, particularly on nearby objects | |
Horner syndrome (disruption of certain nerve fibers that connect the eye and the brain) | On one side of the face, a drooping eyelid, a small pupil that is slow to widen in response to darkness, and decreased sweating If the cause of Horner syndrome is a disorder (such as migraines or a lung tumor) or an injury, other symptoms |
An eye injury or eye surgery | In people who have had an eye injury or eye surgery Sometimes pain with exposure to bright light and/or eye redness |
Physiologic anisocoria (pupils that are normally different sizes) | Present for a long time No symptoms or abnormalities found during the examination A difference of less than 1/16 inch (about 1 millimeter) in pupil size and pupils that constrict normally in response to light |
Double vision and a drooping eyelid Sometimes, in people who have had a head injury or who have a bulge (aneurysm) in an artery supplying the brain, bleeding in the brain, diabetes or hypertension that affects the blood vessels, or a brain tumor | |
* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. | |
COPD = chronic obstructive pulmonary disease. | |