Red-green color blindness is the most common type of color deficiency. Also known as deuteranopia, this is most likely a congenital condition, meaning that you’re born with it.
If you have this type of color blindness, you may have difficulty seeing different shades of red, green, and yellow. However, you may not be aware of these vision deficiencies until they’re pointed out by a loved one or detected by a doctor.
Read on to learn what you need to know about deuteranopia and how an eye doctor may help correct it.
A person with “normal” color vision can see all combinations of the three primary colors — red, blue, and green — in their true form.
This is also known as trichromatism. In all, it’s estimated that the human eye can see 10 million different variations of these colors.
Deuteranopia is a type of red-green color blindness characterized by the inability to distinguish red and green pigments. Protanopia is another type of red-green color deficiency. Both are primarily caused by recessive genes in the X chromosome.
Your ability to see colors is dependent on three genes: OPN1LW, OPN1MW, and OPN1SW. These genes produce instructions for making pigments that contribute to your retina’s light receptor cells, which are located in the back of your eye.
Light receptor cells can be broken down into two parts:
Both cones and rods transmit signals to the brain to help produce vision. Cones provide vision for bright light, which includes color vision, while rods are used for dim light conditions.
Red-green color blindness is typically caused by genetic mutations.
Color blindness occurs when there are genetic deficiencies with one or more of the three cones: L, M, and S.
Red-green color vision deficiencies occur when there are defects with the OPN1LW (red pigment cone) and OPN1MW (green pigment) genes. These affect the way that color wavelengths are detected by the cones in your retina.
Deuteranopia means defects within the green cone pigments, while protanopia results from defects in the red cone pigments.
On the other hand, S cones (dictated by the OPN1SW gene) create blue-yellow color vision deficiencies. This type of color blindness is considered rare.
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It’s estimated that red-green color vision deficiencies occur in 1 out of 12 men and 1 out of 200 women, according to the UK National Health Service.
Less commonly, red-green color blindness may sometimes be acquired, rather than inherited. Possible causes may include:
- retinal diseases
- issues with the optic nerve
- age-related conditions, including macular degeneration and dementia
- exposure to organic solvents, such as fertilizers
- side effects from antimalarial drugs, including chloroquine
- prescription medications taken for high blood pressure, mental health disorders, autoimmune diseases, and infections
According to the National Eye Institute, deuteranopia is typically mild.
If you have deuteranopia, you may confuse red and green pigments. You may not realize you’re confusing these colors until someone points out the differences to you.
It’s also possible for symptoms of deuteranopia to be so mild that you don’t even know about it until you have an eye exam.
Symptoms of red-green color blindness may include difficulty seeing reds and greens as well as their variations, including oranges and browns.
Red-green color blindness can be further broken down into two subtypes that help describe varying degrees of color vision deficiency:
- protanomaly (primarily red color deficiency)
- deuteranomaly (primarily green color deficiency)
With a protanomaly, you may confuse the following colors:
- some shades of blue with dark pinks, reds, and purples
- black with multiple shades of red
- mid-greens with oranges
- dark brown with dark reds, greens, and oranges
And, with a deuteranomaly, you may confuse the following:
- mid-reds with mid-greens
- mid-reds with mid-brown
- bright greens with yellows
- blue-greens with either mid-pinks or gray
- pale pinks with light gray
- light blues with light purples
You can test at home for color blindness, either on paper or on a computer screen. This is known as a color vision test, or the Ishihara color test.
Such tests usually contain circles with varying colors that have numbers in their centers. If you can’t read the numbers, then you might have a color vision deficiency like deuteranopia.
However, even if you take a test at home or online, you’ll still need to see an eye doctor for an office visit. Your family doctor may refer you to an optometrist or ophthalmologist.
Your doctor will administer a color vision test via cards that contain varying colors and symbols. They may also test one eye at a time.
Currently, there’s no cure or treatment option available for deuteranopia.
However, corrective contact lenses or glasses may help neutralize red-green color blindness. These come in the form of tinted lenses or filters that go over your glasses and can help you see reds and greens more clearly.
Since red-green color blindness is largely inherited, you may experience issues with seeing certain colors unless you wear corrective lenses.
In the rare cases that deuteranopia is caused by a medical condition, treating the underlying issue may help resolve color vision deficiencies.
Inherited deuteranopia isn’t a progressive condition. This means if you have a mild or severe case, you should expect the same severity of symptoms going forward, without worsening.
Deuteranopia refers to red-green color blindness. This is the most common type of color vision deficiency, and it’s usually genetic.
While there’s no cure for deuteranopia, corrective contact lenses or glasses can help you see better. If you suspect you have issues with red-green color vision, see your eye doctor for an exam.