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Understanding Eye Colour

eyes green close up woman

Eye colour is a hereditary trait that depends on the genes of both parents, as well as a little bit of mystery. The colour of the eye is based on the pigments in the iris, which is a coloured ring of muscle located at the center of the eye (around the pupil) that helps to control the amount of light that comes into your eye. Eye colour falls on a spectrum of colour that can range from dark brown, to grey, to green, to blue, with a whole lot of variation in between. 

Genetics

The genetics of eye colour are anything but straightforward. In fact children are often born with a different eye colour than either of their parents. For some time the belief was that two blue-eyed parents could not have a brown-eyed child, however, while it’s not common, this combination can and does occur. Genetic research in regards to eye colour is an ongoing pursuit and while they have identified certain genes that play a role, researchers still do not know exactly how many genes are involved and to what extent each gene affects the final eye colour.

The Iris

Looking at it simply, the colour of the eye is based on the amount of the pigment melanin located in the iris. Large amounts of melanin result in brown eyes, while blue eyes result from smaller amounts of the pigment. This is why babies that are born with blue eyes (who often have smaller amounts of melanin until they are about a year old) often experience a darkening of their eye colour as they grow and develop more melanin in the iris. In adults across the globe, the most common eye colour worldwide is brown, while lighter colours such as blue, green and hazel are found predominantly in the Caucasian population. 

Abnormal Eye Colour

Sometimes the colour of a person’s eyes are not normal. Here are some interesting causes of this phenomenon.

Heterochromia, for example, is a condition in which the two eyes are different colours, or part of one eye is a different colour. This can be caused by genetic inconsistencies, issues that occur during the development of the eye, or acquired later in life due to an injury or disease. 

Ocular albinism is a condition in which the eye is a very light colour due to low levels of pigmentation in the iris, which is the result of a genetic mutation. It is usually accompanied by serious vision problems. Oculocutaneous albinism is a similar mutation in the body’s ability to produce and store melanin that affects skin and hair colour in addition to the eyes.

Eye colour can also be affected by certain medications. For example, a certain glaucoma eye drop is known to darken light irises to brown, as well as lengthen and darken eyelashes.

Eye Colour - It's More Than Meets the Eye

It is known that light eyes are more sensitive to light, which is why it might be hard for someone with blue or green eyes to go out into the sun without sunglasses. Light eyes have also shown to be a risk factor for certain conditions including age-related macular degeneration (AMD).  

Colour Contact Lenses

While we can’t pick our eye colour, we can always play around with different looks using coloured contact lenses. Just be sure that you get a proper prescription for any contact lenses, including cosmetic coloured lenses, from an eye doctor! Wearing contact lenses that were obtained without a prescription could be dangerous to your eyes and your vision.  

Thank you for trusting your eyecare with us over the years.  The Foresight Eyecare team follows the government mandate to reduce the spread of the COVID-19 pandemic.  After December 2020 announcements made by the Alberta Government, our clinic is following the revised Infection Prevention and Control policy by the Alberta College of Optometrists.

Patients interested in obtaining eye exam services or eye care products can be seen by appointment only.  Please call ahead, and staff will arrange an appointment time and ask COVID-19 screening questions.  If you have any symptoms of cough, fever, runny nose or shortness of breath, we ask that you call or e-mail us and do not attend the clinic for your scheduled visit.   Within the clinic, please wear a mask and use the hand sanitizer at reception.  Our clinic complies with the City of Calgary bylaw requiring mask covering over the age of two years old.  For patients who are unable to wear a face covering due to medical reasons, the patient can be scheduled for an appointment at a time when minimal number of other patients are in the clinic such as at the beginning or end of the day to ensure appropriate physical distancing requirements.

We are using disposable disinfectant wipes on all surfaces and devices such as front desk counters, chairs, handles in exam rooms and waiting room.  All eyewear that have been touched by patients are continually being sanitized.   Any toys and magazines are stored at this time.  Examination areas are being sanitized with hospital grade disinfectant.  Debit and credit cards but NO CASH payments will be accepted.

COVID-19 symptoms are not always obvious.  We want to fend off this pandemic and minimize risk to our patients and the Foresight staff as front line health workers.   Contact that is closer than 2 m (6 feet) is to be avoided, with barriers in place when this cannot be avoided. We choose to continue to do our work and cautiously take care of our patients with compassion, humility, gentleness, and patience.   It is a challenging and new experience for many of us, so let‘s support each other and prevent virus spread!  Beyond 2020, our focus is on take care of you and keeping Clean Hands, Clear Heads and Open Hearts.   For more information, please refer to the following web pages or phone Health Link 811.

www.albertahealthservices.ca

www.collegeofoptometrists.ab.ca

Drs. Dianna Leong, Anh Bui, Andrew Chan