Ideal Optical

Colour Vision in Mississauga

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The Human Eye Can See Millions of Colours

Have you ever thought about how our eyes see colour? Every kid has asked why the sky is blue, but how long has it been since you have thought about it too? It all has to do with the wavelengths of visible light and how our eyes receive this information.

Without getting too much into the physics of it all, let’s discuss the physiology of our eyes.

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How the Eyes Work

Everything about our eyes is designed to focus light and interpret and transmit it as information to the brain:

  • The cornea, iris, ciliary body, and lens all work on focusing light onto the retina.
  • The choroid, aqueous and vitreous humours, and the lacrimal system provide balance, maintain pressure, and nourish the ocular tissues.
  • Light that enters the eye is refracted through the cornea, aqueous humour, lens, and vitreous humour before it reaches the retina. How well these parts work together account for visual acuity.
  • The visual information received by the retina is then transmitted to the brain through the optic nerve.

The retina contains 2 types of photoreceptor cells: rods and cones.

The eye has 3 different types of cones that contain several types of pigment, each reacting to different light wavelengths. The 3 types of cones are called either blue, green, or red, or short (S), medium (M), or long (L), based on the wavelength of light they react to.

When the eye is missing some of these pigments, this is called colour deficiency.

What Is Colour Deficiency?

Also known as colour blindness, colour deficiency occurs when there’s an imbalance in the types of cones in the retina. It is usually inherited but can also occur after trauma, as a side effect of medication, or from certain diseases.

Types of Colour Deficiency

There are 3 types of colour deficiency:

  • Red-Green colour blindness is the most common type, and makes it difficult to see the difference between red and green.
  • Blue-yellow colour blindness is less common, and makes it difficult to see the difference between blue and green or yellow and red.
  • Complete colour blindness is pretty uncommon. Also known as monochromacy, those with this colour deficiency cannot see the difference between any colours and may be more sensitive to light.

How Is Colour Deficiency Detected?

The test for colour deficiency is easy and nonintrusive. The most well-known test is called the Ishihara test and includes a set of coloured dotted plates with a different number. Those with colour deficiency will see a different number than those with normal colour vision, or will be unable to differentiate the numbers at all. Our office also has a Farnsworth D15 test which can be performed if the Ishihara test is failed. This test is often required for certain employment applications such as the police force.

Children with colour deficiency will likely not realize they see differently than their peers. Because many children’s learning materials are colour coded, children should be tested for colour deficiency, which can be done during a routine pediatric eye exam. A child with colour deficiency may struggle in a regular educational setting.

How Is Colour Deficiency Treated?

There’s no cure for colour deficiency. If discovered early, children can learn to tell the colours apart and proper colour naming. There are special eyeglasses, contact lenses, and filters that can help those with colour deficiency distinguish colours.

If you have questions about your colour vision or suspect your child may have a colour deficiency, please call our office and book an appointment. We would be happy to check for you!

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Where to Find Us

We are in the Mississauga Marketplace in the South East corner of Hurontario and Eglinton Avenue. Parking is free, and wheelchair accessible spots are available. Visit us today!

Our Address

#3A-4559 Hurontario Street
Mississauga, ON L4Z 3L9

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Our Hours

10:30 AM — 5:00 PM
10:30 AM — 5:00 PM
10:30 AM — 5:00 PM
10:30 AM — 5:00 PM
10:30 AM — 5:00 PM
10:30 AM — 4:00 PM

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