Color Blindness or Color Vision Deficiency

What is color blindness?

Color blindness is the inability to see color. It is not some form of blindness, but when you are color blind, it is difficult for you to distinguish between certain colors, like red and green or blue and yellow. The inability to see red-green is the most common form of color blindness. Less common seems to be the inability to see blue-yellow. Contrary to popular belief, it is very rare for a color blind person to only see shades of gray.


Is color blindness inherited?

Color blindness may be inherited or caused by disorders of the optic nerve or the retina.

Acquired color blindness affects only the eye that presents a problem and may worsen with time. Patients with color blindness that is caused by other disorders usually have difficulty distinguishing blue and yellow colors.

Inherited color blindness is much more frequent. It affects both eyes and does not worsen with time. This type of color blindness is found in 8% of all males and 0.4% of all females. Color blindness is connected to the X chromosome and in almost all cases it is carried from mother to son.

Color blindness may be partial and only affect some colors or total and affect all colors. Total color blindness is very rare. The patients with total color blindness usually present other ophthalmological problems.

What causes color blindness?

Our eyes are capable of distinguishing colors, as well as brightness, because at the posterior segment there are cells known as cones and rods. Cones recognize color and rods brightness. Cones are gathered in the central area of the retina and contain three light-sensitive pigments: red, green and blue. Those with color blindness have partial or total lack of one or more of the above pigments. Depending on the number of cones in each patient with color blindness, the degree of color blindness varies. A person that is red and green color blind does not have enough red and green cones. This, of course, does not mean that the patient sees everything in black and white, but that he confuses red with green or brown, as well as blue with purple. Color confusion in the color blind patient depends on lighting conditions. For example, the person that can't distinguish green might, under intense sunlight, distinguish a strong green as green. On the other hand, under low artificial light he may confuse the green color with brown or even red.

Patients with normal color perception are called trichromats..

Patients with partial color blindness and lack of one pigment are called anomalous trichromats (this is the most frequent type of color blindness). A color blind patient of this type has total lack of one cone pigment.
What are the symptoms of color blindness?
The symptoms of color blindness depend on various factors, for example if the problem is inherited or acquired, partial or total.

Difficulty in recognizing red and green (most common conditions)
Difficulty in recognizing blue and yellow (less common conditions)

The symptoms for more serious inherited problems of color blindness and some types of acquired color blindness may be:

Objects appear in various shades of grey (this appears in total color blindness and is very rare)
Decreased vision

Can color blindness be diagnosed?

Color blindness can be detected with special chromatic tables called Ishihara Test (Image 1). In every table there is a number formed by colored dots. The patient must recognize the number on the table in his hands under well-lit conditions. As soon as color blindness is diagnosed, a more thorough examination of the condition is in order.





Can color blindness be cured?

Color blindness cannot be cured. Nonetheless, its diagnosis from an early age is very important since during the school years a large portion of instructive material is based on color perception. Knowing the problem makes it easier for the child to face any learning difficulties based on color perception. So, if your child is color blind, you should notify his teacher, so that the lessons can be organized in such a way that will help with these learning difficulties.

The person that suffers from this eye condition should not be working with machinery or buttons with red or green colors and will have to find different ways to tell the colors of pills, objects, etc. It is important to point out that there are ways to help someone overcome this difficulty to distinguish colors. For example, someone with color blindness might tell his clothes apart in the closet by tagging them or placing them by color, so that it's easier for him to find them. Another example is that the red light of traffic lights is always on the top, even if we can't see its color.

Finally, we should mention that color blindness has some “advantages”. People with color blindness seek outlines to compensate for color confusion, that's why they can, for example, easily distinguish anything or anyone that is camouflaged. Furthermore, these people have sharper night vision than people with normal vision.

Remember: our ophthalmologist is the best source for responsible answers on issues related to your eyes and their health. Under no circumstances is information taken from our website intended to replace him. Seek your doctor for complete information.




Τμήμα Αμφιβληστροειδούς και Ωχράς Κηλίδας