Color blindness or Daltonism: what can be done about it?

With color blindness, the ability to distinguish colors is less than normal. In the Netherlands, approximately one in twelve men is color blind and one in two hundred women. Many more men because the main color disorder is passed on via the X chromosome. Complete color blindness (achromatopsia) occurs in a very small group: approximately one in thirty-three thousand people. These people perceive the world through a kind of gray filter. Can color blindness be remedied?

Article content

  • Daltonism
  • Color blindness
  • Can a newborn distinguish colors?
  • Seeing colors
  • The most common forms of color blindness
  • Red-green color blindness
  • Blue-yellow color blindness
  • Diagnosis of color blindness and the different tests
  • Problems at school due to color blindness
  • Problems in traffic due to color blindness
  • For (among other things) which professions is color blindness a disability?
  • Treatment of color blindness


Daltonism/color blindness, was first described in 1794 by scientist John Dalton . He could hardly tell red and green apart. Color blindness is actually a misnomer, the majority of people who are color blind can certainly see colors, but have difficulty perceiving some colors.

Color blindness

Color blindness is the limited ability to tell some colors apart due to a defect in the cones. The cones in the eye are the specialized cells in the retina (light-sensitive), they are located at the back of the eye. There are three types of cones, they are sensitive to blue, green and red light. If one or more of these types of cones show defects, the result is color blindness. This is usually hereditary.

Can a newborn distinguish colors?

Babies are born color blind. Only after four months does the ability to distinguish colors begin to develop.

Seeing colors

Seeing colors does not have much to do with perceiving light. Light can be described as a part of the electromagnetic spectrum that lies between three hundred and eighty and seven hundred and forty nanometers. Our eyes can sense light in different wavelengths and can filter wavelengths. Filtering is a task of light-sensitive pigments in the eye. They split the light into red, blue and green. You don’t necessarily need light to see color. If you close your eyes, you can still see colors. Our eyes capture light and colors via cones and rods (receptors) on the retina. The cones are responsible for color: they convert red, green and blue. The distribution of the cones is approximately: 60% red, 30% green and 10% blue. Most cones are located on the outer edge of the retina. Sufficient light is required to convert color; if there is too little light, the rods take over. These provide visibility in low light conditions, a kind of night vision goggles. If the rods do not work, a person is night blind . The cones and rods receive light stimuli, which are converted by the brain into image information.

The most common forms of color blindness

  1. Red-green color blindness
  2. Blue-yellow color blindness

Certain eye conditions, such as macular degeneration, can cause color blindness. Toxic effects of various medications, for example chloroquine (an antimalarial drug), can also cause color disturbances.

Red-green color blindness

  • This form of color blindness is the most common.
  • The differences between light red, green, orange and brown are not clearly seen.
  • This form of color blindness is caused by an abnormal gene on the X chromosome.
  • Many more men suffer from it than women. It mainly affects men, because women have a second X chromosome. This cancels out the effect of the abnormal gene.
  • The abnormal gene can be passed on by women to their children.

Parents can pass on red/green color blindness to their children. Every child has a certain chance of being a carrier or color blind:

  1. Mother and father both have normal color vision : every child born has normal color vision.
  2. Mother has normal color vision, father color blind : a son has normal color vision, a daughter is always a carrier.
  3. Mother carrier, father normal color vision : a son has a 50% chance of being color blind, a daughter has a 50% chance of being a carrier.
  4. Mother carrier, father color blind : a daughter has a 50% chance of being a carrier and a 50% chance of being color blind and a son has a 50% chance of being color blind.
  5. Mother color blind, father normal color vision : a son is always color blind, a daughter is always a carrier.
  6. Mother and father are color blind : every child is color blind.

Blue-yellow color blindness

  • Blue-yellow color blindness is much less common than red-green color blindness.
  • If you have this form of color blindness, it is difficult to see the difference between the colors blue and yellow.
  • You can inherit blue-yellow color blindness.
  • It is not linked to the X chromosome and therefore affects men and women equally.

Diagnosis of color blindness and the different tests

Color blindness is usually discovered during childhood when testing the eyes. But it can also be noticed during a medical examination for a job where color blindness is an obstacle.

The different tests:

  • Ishihara’s test : this test is suitable for determining abnormalities in the vision of the colors red and green. However, it is difficult to determine with this test which form of color blindness is involved. The test is also less suitable for children between four and six years old and for illiterate people. You have to search for a number or letter in a jumble of colored dots. There is a variant available for them that uses shapes (instead of numbers or letters).
  • America Optical-Hardy test, also called Rand and Rittler test . This is the most comprehensive test that, in addition to abnormalities in seeing red and green, can also determine whether someone is blue-color blind. It is even possible to determine the strength of the deviation with this test. Colorful figures must be sought against a gray background, the test is suitable for all test subjects.

Problems at school due to color blindness

A child who is color blind may learn from others that what he or she sees as a certain shade of green is called brown. Different shades of green can be distinguished and named in this way. But sometimes color combinations are chosen so awkwardly that it is impossible for someone with color blindness to see anything. Children who are color blind often have difficulty keeping up at school. This is because many teaching methods are used that use colors. For example, think of mini loco and puzzles. If it is not known that a child is color blind, assignments may be incorrectly considered incorrect. In higher classes the child encounters other problems. For example, in language teaching/parsing, a teacher gives each sentence part its own color. Maps in atlases and graphs in textbooks can also cause problems. The Cito final test (group 8) is issued in a special version for children who are color blind.

Problems in traffic due to color blindness

At a railway crossing without railway barriers, life-threatening situations can arise because the red signal disappears for many color blind people against the background of the black canopy of the signal.

For (among other things) which professions is color blindness a disability?

  • Pilot
  • Laboratory Technician
  • Electrician
  • Working in the transport sector: train driver, driver

In the above professions, dangerous situations can arise if someone cannot distinguish colors properly. This is very different for painters, where color blindness can actually result in fun and creative color combinations. For example, Vincent van Gogh and Herman Brood were color blind!

Treatment of color blindness

The hereditary forms cannot be treated. If the disorder is due to eye disorders or medications, the cause can sometimes be addressed.