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What is Colour Blindness?


The inability to perceive colours or colour blindness is a generally hereditary disability which inhibits someone's ability to differentiate between colour tones. Colour blindness is caused by damage to the cones in the eye's retina, typically affecting an individual's power to distinguish between variants of red or green, but occasionally impacting the perception of additional colours as well.


The perception of colour is dependent upon cones located in the eye's macula. Humans are commonly born with three kinds of pigmented cones, each perceiving different wavelengths of colour tone. This is similar to wavelengths of sound. When it comes to pigment, the size of the wave is directly linked to the perceived colour tone. Long waves are seen as red tones, moderately-sized waves are seen as greens and short waves are perceived as blues. Which pigmented cone is affected has an impact on the nature and seriousness of the colour blindness.


Since it is a sex-linked genetically recessive trait, green-red colour deficiency is more frequent in men than in females. Nevertheless, there are a small number of females who do experience varying degrees of colour blindness, particularly yellow-blue deficiencies.


Colour blindness is not a devastating disability, but it can hinder educational development and limit choices of professions. The inability to see colours as peers do could immediately hurt a student's self-confidence. For working people, colour blindness could become a drawback when competing against normal-sighted colleagues in certain fields.


Eye doctors use several tests for the condition. The most widely used is the Ishihara colour exam, named after its inventor. For this test a plate is shown with a circle of dots in different colours and sizes. Within the circle appears a digit in a particular colour. The patient's capability to make out the number within the dots of contrasting tones reveals the level of red-green colour sight.


While hereditary colour blindness can't be corrected, there are a few steps that can help to make up for it. Some evidence shows that using tinted contacts or anti-glare glasses can help to perceive the distinction between colours. More and more, new computer programs are becoming available for regular PCs and for mobile devices that can help users enhance colour distinction depending upon their particular condition. There is also exciting research being conducted in gene therapy to improve colour vision.


How much colour blindness limits an individual is dependent upon the kind and degree of the deficiency. Some individuals can adapt to their condition by familiarizing themselves with substitute cues for coloured objects or signs. For instance, many individuals are capable of learning the order of traffic signals or contrasting objects with colour paradigms like a blue body of water or green trees.


If you notice signs that you or your loved one could have a colour vision deficiency it's advised to schedule an appointment with an optometrist. The earlier you are aware of a problem, the sooner you can help. Feel free to call our Squamish, BC or West Vancouver, BC optometrists for additional information about colour blindness.