Our NEW LOCATION is now OPEN at 107-1411 Cook Street, Victoria BC, V8V 0E8. We now have a full range optical for all your eyeglass needs. We cant wait to show you!

Inner Harbour Optometry logo white

Unequal Pupil Size – Causes, Symptoms & Treatments

man sitting outside

Our pupils change size due to a number of things like light or how we are feeling. Generally, our two pupils change size equally. However, anisocoria refers to individuals who have pupils of differing sizes. This week’s article will explore this medical condition’s causes, symptoms, and treatments. Read on to learn about unequal pupils!

What & Where Is The Pupil Located?

Before we go on it is important to understand the purpose and location of the pupil. It is located in the center of the iris. When you are looking at someone’s eyes the black hole in the center of their colored iris is called the pupil. The iris’s muscles help constrict and widen the center hole to allow just enough light to enter into the eye. You don’t have to think about changing your pupil size because it is done involuntarily through a process referred to as the pupil reflex.

Want to know more about why pupils change size?


What Are The Causes Of Unequal Pupil Size?

Anisocoria may occur in an individual because of any number of reasons. Some people are born with it, whereas others can develop it later in life. However, in all cases, it is important to determine if the cause of unequal pupil size is physiological or due to something else like ocular trauma, cranial third palsy, or Horner’s Syndrome. Physiological anisocoria refers to those who have unequal pupil sizes but it is not due to any underlying medical issue. Unlike, say Horner Syndrome, which is caused by the damage to the sympathetic nervous system. The U.S. National Library of Medicine explains that “The sympathetic nervous system prepares your body for physical and mental activity.  It makes your heart beat faster and stronger, opens your airways so you can breathe more easily, and inhibits digestion.” This system also regulates pupil size. The cause of damage to the sympathetic nervous system could be due to any number of things, which include a stroke, tumor, neck or chest trauma. The root cause of why one exhibits anisocoria is extremely important to determine. As the underlying causes could become fatal if left untreated.


What are the Symptoms of Anisocoria?

It’s important for patients to be aware of symptoms so that they can take immediate actions. Too often people will brush off issues in order to avoid seeing their family eye care physician, or they may just think it will go away. And sometimes it does. However, in cases of those patients who have unequal pupil sizes due to an underlying medical condition, it is imperative these symptoms be checked by an eye professional and diagnosed. Some symptoms to watch out for include:

  • Pupil size difference may be obvious or subtle
  • Patient may exhibit ptosis (droopy eyelid)
  • May have no visual effects
  • Face or neck pain
  • Light sensitivity
  • Headache
  • Double or blurred vision
  • Hand weakness
  • Vision issues

Dr. Sharma always reminds patients to err on the side of caution when it comes to your eyes. So if you think there just isn’t something right, come in for a check-up, your eyes will thank you!


Treatments For Anisocoria

In order to treat anisocoria, the underlying issue (or lack thereof) must be first determined. The first step in doing this is seeing your local Victoria, B.C. optometrist for a comprehensive eye exam. Your eye doctor will examine your eyes thoroughly and even order additional testing, like an MRI or X-ray. For example in the case of someone who has unequal pupil size because of Horner’s Syndrome, your optometrist may send you to a neuro-ophthalmologist who may order an MRI to locate the area that is causing the abnormality. It is extremely important to locate areas of abnormality and seek appropriate treatment for them because anisocoria is considered an after effect of a greater issue in the body like an aneurysm, or brain tumor. If these are left untreated it can lead to death. This is a great example of how our bodies are interconnected. Sometimes issues surface in the eye, which really is pointing to a greater underlying issue.


Do you need a full comprehensive eye exam? Book an appointment with Dr. Sharma by giving our office a call or easily booking online

We are Victoria B.C.’s trusted family eye care center.