Color Blind Test

The retina of the eye has cells, called cones, which detect color and which are necessary to see color properly. There are three types of cone cell, sensitive to red, blue, or green light. If one or more of these cone cells are faulty, then color blindness results.

Colour blindness may also occur because of certain diseases such as macular degeneration or from side effects of medicines.

There are a number of different types of color blindness. The most common being red/green colour blindness, which involves confusion between the colors red and green. This type of color blindness is inherited through a faulty colour vision gene and has two forms:

• different shades of red appear dull and indistinct


• greens, oranges, pale reds and browns all appear to be the same hue, distinguished only by their intensity

Those who are not colorblind should be able to distinguish the number 6 in the image to the right.



Other, more rare, forms of colour blindness are:

• where blues and yellows can't be distinguished.


• All colours are seen in black and white.

The Ishihara Color Blind Test is the most common test used to diagnose colour blindness, it is a test for red/green color confusion.
This test consists of a number of colored pictures each of which contain a circle of dots appearing randomized in color and size. Within the pattern are dots which form a number visible to those with normal color vision and invisible, or difficult to see, for those with a red-green color vision defect.

The The Farnsworth D-15 test is well known and belongs to a category of color blindness tests called Color Arrangement Tests. The tests are based on different colors which have to be arranged in the correct order. According to the order you choose a tester can find out if you are suffering from a red-, green- or blue-color deficiency.

The French optician Jean Jouannic offers an Online Multiple Choice Color Blindness Test based on 31 images. The images are either hidden signs and letters or a handful of colors which you have to match to a choice of color names. As colorblind people show great difficulties matching color names to colors, this is another appropriate method to test color vision. The test has some nice statistics when you have finished and tries to quantify your color blindness in detail.

Colour blindness will not becessarily affect your life but it may limit your choice of career.

For example, being color blind needn't stop someone driving as traffic lights can be distinguished by the position of the light. But people affected by color blindness will be affected in their choice of careers by not being able to take up a career where good colour vision is important, including pilots, electricians, train drivers and some jobs in the printing, fashion and design industries.