Color blindness, or color deficiency, isn’t a debilitating disease. Not like actual blindness. But for the 1 in 12 men and 1 in 200 women worldwide who struggle with color blindness, it is a real and saddening problem.

Color blindness happens when you aren’t able to see colors in a normal way. It typically happens when someone can’t differentiate between certain colors. This most commonly is between greens and reds, occasionally including blues.

The normal eye pieces together vision with information from two types of cells in the retina: rods and cones. These specialized cells help translate light waves into vision. Rods detect only light and dark and are sensitive in low-light situations. Hence, they are your “night vision”. On the other hand, cones detect color and are clustered near the center of your vision. Your cone cells are programmed to see one color, either red, green, or blue. When your brain puts these signals together, it perceives color.

When one or more type or “color” of cone cell is missing, not working, or is detecting a different color than it should, color blindness results. When all three color detecting cones are missing, severe color blindness occurs. Whereas when just one is missing or defective, there is only a case of mild color blindness.

A person with severe color blindness will only see things in shades of gray. Fortunately, this form is relatively uncommon. Most forms of color blindness affect people’s ability to see colors in low light conditions when the cones are even less sensitive. Generally, color blindness affects both of a person’s eyes equally and stays about the same throughout life. Although most cases are present at birth, you can develop color blindness later in life.

What Are The Symptoms Of Color Blindness?

As you probably can guess, the symptoms of color blindness are mostly related to not being able to perceive colors correctly. However, in severe cases other symptoms may manifest themselves.

Common symptoms of color blindness are usually detected when a child is learning his or her colors. A parent or teacher often notices a difficulty and then color blindness is confirmed by an eye doctor. These symptoms include trouble seeing colors and an inability to differentiate between similar shades of colors or colors like red and green or blue and yellow.

In severe cases, color blindness may affect the sharpness, or acuity, of vision. If a person’s color blindness is so severe that they can only see in shades of gray, also known as achromatopsia, other symptoms may occur. These include amblyopia, nystagmus, light sensitivity, or poor vision.

What Causes Color Blindness?

Most people with color blindness are born with the condition. This makes it a widely congenital condition. In most cases, it is usually passed on from mother to son. Since the genetic defect is on the X chromosome, men are much more likely to be color blind than women. This defect causes the cones to not work properly or be missing altogether.

If color blindness develops later in life, there are generally only a few causes. Disease, trauma, toxic drug effects, metabolic disease, and vascular disease are the primary causes of non-congenital color blindness. It may also be linked to damage to the retina or optic nerve. Unlike congenital color blindness, when caused by a disease it can affect both eyes differently and get worse over time.

Who Is At Risk For Color Blindness?

Not everyone is at equal risk for being color blind. As mentioned, men have a much higher rate of being born with color blindness than women. It is estimated that 8% of all men have some form of color blindness. Men of Northern European decent are also at higher risk. If a parent has the defect (or if both do) than their children are at increased risk.

Those at risk for developing disease-related color blindness include diabetics, those with glaucoma, those with Alzheimer’s or Parkinson’s, chronic alcoholics, and cancer patients. Some drugs can also increase your risk. For example, rheumatoid arthritis drug hydroxychloroquine (Plaquenil) can cause color blindness.

How Is Color Blindness Tested?

Unlike testing for some eye-related diseases, testing for color blindness is easy. An eye doctor will use a set of images called Ishihara color plates. This is one of the most common and most reliable color blindness tests. You simply look at the images and determine which number is embedded in dots of color. All the dots are similar in color, but the number is different than the background. If you are unable to differentiate the number from the background, then you have some form of color blindness.

Should I Be Tested For Color Blindness?

There is no formal guideline on whether or not you should be tested for color blindness. However, if you have a family history of the disorder or are suspicious that you or your child has it then there is no harm in taking the simple test to detect it.

How Is Color Blindness Diagnosed?

After taking a test with the Ishihara color plates, your eye doctor can easily diagnose color blindness. However, there is more than one form of it. For example, red/green color blindness is the most common type. It makes reds and greens look similar, more like a brown. Another type is blue/yellow color blindness which has the same affect but with different colors. Depending on the origin of your color blindness, your eye doctor may be able to help provide treatment.

How Is Color Blindness Treated?

Unfortunately, congenital color blindness is not treatable. There is currently no known cure for the disorder. However, it is only minimally impacts everyday life. In fact, most people who are color blind can see most colors clearly and only struggle with a few. Some new treatments such as special contact lenses or glasses may help with color perception, but do not fix the disease itself. For patients with acquired color blindness from a disease, your eye doctor will develop a specialized treatment plan.