What Is Anisocoria?

Anisocoria is when your eye’s pupils are not the same size. The pupil enables light to get in the eye so that you can see. Anybody can have pupils that vary in size without any issues. In reality, one from five people have pupils that are generally different sizes.

Sometimes, though, having unequal pupil size can be a symptom of a serious eye issue. People who may get anisocoria consist of those who have a nervous system issue, a history of damage to the eye, risk of having a stroke, a viral infection, Adie’s tonic pupil (when one pupil does not respond to light along with the other pupil).

One pupil look noticeably larger or smaller than the other

Causes Of Anisocoria

Many cases of moderate anisocoria are normal and do not have any underlying pathology or history of injury. Usually, these cases of anisocoria where one pupil is bigger than the other by less than 1.0 mm without any apparent cause are called basic anisocoria, benign anisocoria or physiologic anisocoria.

In one research study of the occurrence of anisocoria, scientists photographed the pupils of 128 normal topics in dim light for 5 successive days. Photos were taken in the morning and afternoon every day.

Fifty-two of the subjects (41 percent) had an anisocoria of 0.4 mm or more at one time or another during these 5 days. At any given picture session, a relatively constant number of subjects (19 percent) showed this amount of mild anisocoria.

The frequency of anisocoria did not differ with the time of day or from day to day; nor was it influenced by the sex, age or eye color of the subject.

Other research also suggests roughly 20 percent of the basic population have mild benign anisocoria.

Substantial anisocoria, nevertheless, can have a number of causes, and some can be medical problems. Causes of significant anisocoria (one pupil larger than the other by more than 1.0 mm) include:

  • Eye trauma. For instance, read about David Bowie’s eyes below.
  • Certain eye medications. For instance, pilocarpine eye drops used to treat glaucoma might cause the pupil of the dealt with eye to be smaller sized than the other pupil.
  • Inflammation of the iris. Iritis (anterior uveitis) can cause anisocoria that generally is accompanied by eye pain.
  • Adie’s tonic pupil. This benign condition (likewise called Adie’s pupil, tonic pupil, or Adie’s syndrome) usually causes one pupil to be noticeably larger than the other. The impacted pupil also does not respond to light. In most cases, the cause of Adie’s pupil is unknown. However it can be related to eye injury (consisting of injury triggered by complicated cataract surgery), lack of blood circulation (anemia) or an infection.
  • Neurological disorders. A variety of conditions that damage nerves in the brain or spinal cord can cause anisocoria. One of the most considerable of these is Horner’s syndrome [see below] People with nerve system conditions that cause anisocoria often also have a drooping eyelid, double vision and/or strabismus. Brain disorders associated with anisocoria consist of strokes, hemorrhage (spontaneous or due to head injury) and, less commonly, certain tumors or infections.

Anisocoria Symptoms

Frequently people do not understand their pupils are various sizes. Some people only notice it when comparing old and recent pictures of themselves.

However, if anisocoria establishes from an eye health issue, you may discover other symptoms connected to that issue. These symptoms may consist of drooping eyelid (ptosis), problems moving your eye, fever, headache and eye pain, lowered sweating.

If you experience any of these symptoms with anisocoria, call an ophthalmologist immediately.


Your eye doctor will analyze your pupils in both a lighted space and a dark room. This enables them to see how your pupils respond to light. This can help them figure out which pupil is irregular.

Your ophthalmologist will likewise inspect your eyes with a slit-lamp microscope. This instrument lets your eye doctor take a look at your eye in little, comprehensive sections. That makes it easier to spot issues.

If you have other symptoms in addition to various pupil size, your eye doctor will do other tests to learn more about your condition.

Anisocoria Treatment

Normally anisocoria does not have to be treated because it does not affect vision or eye health. If anisocoria is associated with an eye illness, that problem will need to be dealt with. If you have concerns about anisocoria, make sure to ask your eye doctor. Your ophthalmologist is dedicated to protecting your sight.

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