People who are colour blind, have a deficiency in distinguishing colours. The general misconception concerning colour blindness is that everyone affected by the condition can only see shades of gray, but that is incorrect! Most people who are colour blind do see some colours although, they may appear washed out and may be easily confused with other colours depending on the type of deficiency they have. Typically, they cannot see reds and greens or in rarer cases a person may have reduced ability to see blues and yellows. Men are usually the ones most commonly affected by this condition. Colour blindness affects the X chromosome and since women have two X chromosomes, if one chromosome is affected by the condition, the other may compensate whereas men only have one X chromosome, so if it is affected, then they will be colour-blind.
Colour blindness is a result of the response failure of the light-sensitive cells in the retina. These do not appropriately react to variations in wavelengths that light emits which generally enable people to see colours. There are three types of colour blindness: red-green blue-yellow and, complete colour blindness.
Red-Green colour blindness is the most common form of colour blindness. It is a mild condition and generally does not hinder the colour-blind person’s daily life. This type of colour blindness dulls colours like red, orange and yellow and make them appear green, yellow or redder.
Blue-yellow colour blindness is a much rarer form than red-green. The affected person will have difficulty distinguishing between blue and green, as well as yellows and reds from pink or violet.
Complete colour blindness, on the other hand, is the complete lack of colour and in some cases may also affect the patient’s visual acuity. People affected by this form of colour blindness will see the world in black, white and gray. Although these extreme cases are very rare.
Being colour blind is hereditary therefore people are born with it. That is why from a young age it is important to have your vision checked. The optometrist can determine whether someone is colour-blind through an Ishihara test, that measures colour deficiencies for colour perception. This is the test with a coloured number made up of different sized dots placed inside a circle of dots of another colour.
Yearly eye exams are also very important because although this condition is mainly based on our genetics, certain factors or diseases can cause people to develop colour blindness, for example: Parkinson’s disease cataracts and, certain medications. In some cases, damaged retinal cells caused by aging or by an injury or damage to the area of the brain where vision is processed, can also cause certain people to develop colour deficiencies.
Make an appointment with your IRIS optometrist to find out more.