Colour Blindness: Causes, Symptoms and Diagnosis

Our eyes are very important to us and we have to pay attention to our eye health if we want them to serve us effectively. There are several problems that can affect our eyes among which blindness is the most dreaded, and even under that, we have several kinds of eye blindness.

This article talks about colour blindness, what it is, causes, types, symptoms, diagnosis and treatment. Learning about this will help you to understand colour blindness and help you take action to prevent against it or seek medical attention if you or someone you know develops symptoms of the eye condition.


What is Colour Blindness?

Colour blindness simply means the inability of the eye to see or differentiate between certain colours properly; it doesn’t refer to blindness in the sense that the eye cannot see at all. Hence, colour blindness is more correctly called color vision deficiency (CVD).

The retina of the eye have millions of photoreceptive cells called rods and cones. Rods are more sensitive to light whiles cones are sensitive to colour perception. People who are colour blind have difficulty in distinguishing between the colours blue and yellow or red and green because of the deficiency or complete absence of these cones. Red-green colour blindness is more common than blue-yellow colour blindness.

Basically there are two forms of red-green colour blindness, which are protanomaly and deuteranomaly. Blue-yellow colour blindness is also called tritanomaly.


1. Protan : People with Protanomaly, have a type of red-green colour blindness in which the red cones in the retina do not detect enough red and are too sensitive to greens, yellows, and oranges. As a result, greens, yellows, oranges, reds, and browns may appear similar, especially in low light.

2. Deutan : Those with Deuteranomaly, have a type of red-green colour blindness in which green cones in the retina do not detect enough green and are too sensitive to yellows, oranges, and reds. As a result, greens, yellows, oranges, reds, and browns may appear similar, especially in low light.

3. Tritan : In tritanomaly, the cones in the retina have reduced sensitivity to the colour blue.  As a result, there is confusion between blue versus green and red from purple. More commonly, tritanomaly is acquired later in life due to age-related or other factors like cataracts, glaucoma and age related macular degeneration.



This is usually an inherited eye condition. Most people are born with it as a congenital defect. These birth defects are as a result of partial or complete absence of the cone cells of the retina which are responsible for picking up colours in the eye.

Males are more affected than females. Although not very clearly understood, having other health conditions can also be a cause. Common causes of acquired colour blindness include :


What are the symptoms?

The symptoms can range from mild to severe. Many do have such mild symptoms that they are unaware that they have a colour deficiency. Mothers can usually observe these symptoms in their children when they are young.

The 2 notable symptoms include:

  • Difficulty distinguishing between colours.
  • Inability to see shades or tones of the same colour

Except in the most severe form, it does not affect the sharpness of vision.


Diagnosis and Treatment

Should you notice any of the symptoms above, your ophthalmologist will be able to conduct a simple test to determine if you have the condition.

The test consists of showing you a pattern made up of multi-coloured dots. If you do not have a color deficiency, you will be able to see numbers and shapes among the dots. If you are colour blind, you will have a hard time finding the number or shape in the pattern.

There is no known cure, contact lenses and glasses are available with filters to help colour deficiencies, if needed. Fortunately, the vision of most colour-blind people is normal in all other respects and certain adaptation methods are all that is required.





How useful was this post?

5 / 5. 1

Related posts