People have eyes of different sizes

What do different sized pupils mean?

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Written by Dr. rer. nat. Geraldine Nagel • Medical editor

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A look in the mirror suddenly draws your attention - don't the pupils somehow look different? Pupils of unequal size can be harmless, but they can also indicate serious health problems. What it can mean when the pupils are of different sizes.

If the pupils are of different sizes, experts speak of anisocoria. There is not always something questionable behind it. It is estimated that around 10 to 20 percent of people have this condition congenitally without any associated health problems.

In addition, there is some slight difference in size between the pupils of all people during the day. In such cases, the difference is usually between 0.2 and 0.4 millimeters, but then normalizes again.

If you only got pupil-expanding eye drops in one eye for an eye examination, a difference in size is also harmless. Other drugs can also cause pupils of different sizes. Usually these are drugs that accidentally get into the eye, such as an asthma spray.

Sometimes an indication of health problems

In addition, pupils of different sizes can sometimes also be an indication of a disease, such as:

  • increased intraocular pressure, e.g. B. from glaucoma (glaucoma)
  • migraine
  • Epilepsy (pupils of different sizes may occur during or after an attack)
  • inflammation of the brain or meninges, such as B. in meningitis or encephalitis
  • increased intracranial pressure, e.g. B. by a ruptured aneurysm, a head injury, a cerebral haemorrhage or a stroke
  • space-occupying changes in the brain, e.g. B. by a brain abscess or a lump in the brain
  • nerve damage, e.g. B. as a result of diabetes mellitus or Horner's syndrome

Reading tip:Early detection of eye diseases - when and for whom?

Different sized pupils: when to see a doctor?

If you notice that your pupils are of different sizes, otherwise no further symptoms occur and the condition normalizes on its own, a visit to a doctor is usually not necessary.

If your pupils are of different sizes and the pupils do not readjust themselves, you should have this clarified by a doctor. Even if you have no further complaints. If you take medication regularly, it is best to notify this during the appointment (even without being asked).

Indication of a medical emergency

However, if you have other symptoms in addition to the pupils of different sizes or if you recently had an accident with an eye or head injury, it may be a medical emergency. In this case, do not hesitate to call the ambulance service (112) or go to an eye clinic as soon as possible. In particular, these include symptoms such as:

Anisocoria. Online information from the U.S. National Library of Medicine: (Status: 8.2.2021)

Anisocoria. Online information from MSD Manual: (as of March 2018)

Anisocoria. Online information from the Pschyrembel: (as of April 2016)

Lang, G. K .: Ophthalmology. Thieme, Stuttgart 2014

Burk, A., et al .: Checklist ophthalmology

additional Information

ICD-10 Diagnostic Key:

You can find the appropriate ICD-10 code for "Pupils of different sizes" here:

Last content check:25.02.2021
Last change: 08.03.2021