Anisocoria means unequal pupil size. Your pupil is that black hole in the center of your eye, which darkness causes to open and sunlight causes closure. Your pupil’s change in size is largely controlled by your autonomic nervous system and iris muscle.
Normally pupil size is even. Yet, it’s not a major health concern if the size of your pupils are slightly different, what’s referred to as physiologic anisocoria. And about 1 in 5 have this type of unevenness.
Also, your pupils can differ in size temporarily, then return to normal. In the absence of other symptoms, briefly unequal pupils are not typically out of the ordinary. A couple of causes for this harmless anisocoria are eyedrops and inhaled medication for asthma.
However, if you have unequal pupil size that fails to equalize within a short time, it can be a symptom caused by a brain, blood vessel or nerve problem.
Some of the causes for pupil size to appear uneven are:
- head injury
- brain tumor
- Adie’s pupil
- brain abscess
- Horner syndrome
- brain hemorrhage
- migraine headache
- brain membrane infection ~ meningitis, encephalitis
- autonomic neuropathy ~ diabetes, syphilis, Sjogrens syndrome
- third cranial nerve damage caused by certain drugs, caffeine, alcohol, a virus, diabetes
You need to seek health care attention immediately if your pupils are suddenly different and you’re also experiencing any of these symptoms:
- stiff neck
- loss of vision
- double vision
- blurred vision
- severe eye pain
- nausea, vomiting
You may not be able to see for yourself that the size of your pupils are uneven. So, you may first discover anisocoria when some one else mentions your pupil size differs.