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Does Eye Colour Change?

closeup of blue eye

Whether your eyes are brown, blue, green or hazel, your eye colour makes you unique! Babies’ eyes naturally change colour in their first year or so of life. However, once you’re an adult, changes in your eye colour could be a signal of a deeper issue. Here’s what you need to know.

How Is Eye Colour Determined?

Eye colour is determined by genetic traits handed down to children from their parents. A parent’s genetic makeup determines the amount of pigment, or melanin, in the front layers of the iris. Consequently, people with brown eyes have a large amount of melanin in the iris, whereas people with blue eyes have much less of this pigment.

Factors That Can Affect or Influence Eye Colour

Although unlikely, there’s a possibility that your eye colour could change in adulthood. Here are a few reasons why:

  • Pupil changes. Pupil size can cause your eyes to appear a different colour. For example, if the pupil widens, not as much of the iris is exposed, making your eyes look darker. Conversely, when your pupils are smaller, your eye colour may appear lighter.

  • Injury. Trauma to the eye can damage the iris, causing tissue loss. This tissue loss can make your eyes seem to be a different colour.

  • Excessive sun exposure. Melanin plays a big role in eye colour. Therefore, sun exposure can lead to eye colour changes. For example, irises that are consistently exposed to the sun can develop freckles which makes the iris darker over time.

  • Acquired heterochromia. This is when an adult develops two different coloured irises or more than one colour in a single iris later in life. There are several causes of acquired heterochromia, including uveitis, ocular melanosis, iris ectropion syndrome and diabetes mellitus. Your optometrist can detect these conditions.

  • Medications. Certain medications can cause eye colour changes. For example, glaucoma medications, called prostaglandins, can permanently turn your eyes a darker shade.

  • Eye diseases. Medical conditions, such as Fuchs heterochromic iridocyclitis (FHI) and Horner’s syndrome, can lead to depigmentation of the iris.

  • Other benign reasons Surrounding lighting can make the iris appear a different colour temporarily. Other normal aging changes to the cornea (e.g. arcus senilis) can make the iris appear lighter at the outer edges.

If you’ve noticed a sudden change in the colour of your eyes, it’s important to visit an optometrist. It could be the sign of a serious condition that could permanently affect your vision.

Eye Doctors and Eye Care Specialists in Edmonton

At Optometrists’ Clinic Inc. in Edmonton, we take the safety and health of our patients’ eyes seriously. If you have concerns about your eye health or simply haven’t had an eye exam in a while, we can help. We also carry designer eyewear and various contact lenses to suit your needs. Contact us today to set up an appointment.


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