Normally, our pupils are round and equal in size between both eyes, but about 20% of the population has naturally different-sized pupils. The difference is usually very small, like one millimeter. Anisocoria is a medical term that refers to pupils of different sizes. If you were born with different sized pupils that is usually not something to be concerned about. However if you suddenly notice a difference in the size of your pupils, then that can be caused by an underlying condition and should be looked at.

What can cause anisocoria?

In 20% of the population, the difference in pupil size is normal and they were born that way. However, we want to focus on the other portion of the population who have anisocoria that does not occur naturally. Among the many causes of anisocoria are:

  • Horner syndrome
  • Central nervous system issues
  • Eye injury
  • Brain tumor
  • Aneurysm
  • Seizure
  • Other vascular changes

What symptoms are associated with anisocoria?

In the event that you have different-sized pupils because of underlying medical conditions, you may experience symptoms such as:

How can anisocoria be treated?

Anisocoria does not currently have a treatment, however the underlying causes or symptoms can be addressed. The majority of the time, anisocoria does not require any treatment because it does not affect your eye health or vision. In the event that it does affect your vision, our eye doctor may be able to prescribe appropriate glasses that can help improve your vision. There may be an underlying medical condition causing the difference in pupil size, and this will be treated appropriately.

After establishing what is causing anisocoria, the eye doctor initiates appropriate treatment. When a patient has uneven pupil size due to an infection, antibiotics or antivirals are prescribed as eye drops to combat the microbes and correct the situation. In case of injury or trauma to the brain caused by abnormal growths, the doctor will refer the patient for additional tests and if needed surgery to remove the tumor and restore your normal vision and pupil size.

Pupils: what are they and how do they work?

Your pupils are the black circles at the center of the colored part of your eye. Based on what situation you're in, they let light in. If it's really bright outside, your pupils usually contract to a smaller size to prevent too much light getting in. Alternatively, if it's dark outside, they expand so that more light can be let in and you can see better.

Access top-quality eye care for an eye exam at our well-established optometry clinic in Olympia, serving patients from the surrounding areas including Lakewood, Tacoma, and Lacey. Call (360) 491-2121 or fill out this form to make an appointment today.
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