What Causes Red-Green Color Blindness in Men?

Color Blindness Mainly Affects Men

Female optometrist examining mans eyes
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Causes of Color Blindness

The most common form of color blindness is inherited. However color blindness can also be caused by diseases such as macular degeneration, poisoning and side effects of medication. Women are usually the 'carriers' of the defect which is passed on through a defective x chromosome. It is mostly men who inherit color blindness, affecting about 1 in 20 men for every 1 in 200 women.

Color blindness explained

In color blindness there are a reduced number of cone cells in the retina of the eye. It is the retina that is responsible for color vision.

There are three types of cone cell, red, blue and green cells, that are sensitive to light. The type of color blindness a person experiences depends on the degree of damage and on which groups of cells are affected.

Vision itself is not affected, only the ability to distinguish between certain colors.

Common Forms of Color Blindness

The most common form of color blindness is red-green color blindness. It is passed on through a faulty color vision gene on an X chromosome as a recessive disorder. This type affects about one in 10 men and has two forms. In one form different shades of red appear dull and indistinct and in the other greens, oranges, pale reds and browns all appear as the same hue, distinguished only by their intensity.

Rare Forms of Color Blindness

In one rare form of color blindness, blues and yellows cannot be distinguished. Another rare form of color blindness means that all colors are seen in black and white.

Is There a Cure for Color Blindness?

There is no cure for defective color vision that is inherited. Color blindness caused by disease or medication side effects can sometimes be treated.

What Are EnChroma Glasses?

EnChroma glasses are a new type of optical device that help people (men) with red-green colorblindness better appreciate color. Although EnChroma does not improve color contrast enough so that a person can pass a colorblindness test, it does help people with colorblindness get a taste of what it is like to have color vision. For example, EnChroma lenses may help people with colorblindness better appreciate things like an orange blazer or a lavender flower petal.

EnChroma is a tinted plastic lens which is coated in nearly 100 layers of dielectic material. This lens works by filtering out certain wavelengths of light that overlap in people with red-green colorblindness. More specifically, by using multi-notch filters, EnChroma lenses effectively drive a wedge into areas of optic interference thus enhancing the perception of reds and greens.

EnChroma is by no means curative and has disadvantages. First, it takes about 30 minutes for EnChroma lenses to take effect. Second, EnChroma glasses are more expensive than regular glasses and can cost a few hundred dollars a pair.

Third, EnChroma lenses won't improve daily functioning in any appreciable way.

Interestingly, EnChroma glasses can also be worn by people without colorblindness. For people with normal vision, EnChroma lenses make colors more vibrant or "pop."

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