6 Causes of Color Blindness

Color blindness, which is sometimes called color deficiency, is a condition in which a person can’t see colors normally. In many cases, the patient can’t tell certain colors apart. Many such patients, for example, can’t distinguish between green and red.

The problem lies in the retina, which contains two kinds of cells for detecting light. Rods detect darkness and light and help a person see in limited light. Cones enable people to perceive colors, and there are three types. Cones enable people to see either red, green, or blue. They send signals to the brain that then determines what colors the person sees.

A patient who is color-blind may have cones that are not working properly. For example, they may be detecting a different color than normal. The color-blind patient may also be missing some cones. In the most severe cases, they may have no cones at all and see everything in shades of gray. Fortunately, this type of color blindness is rare. At the other end, people with mild color blindness can perceive colors more or less normally in well-lit areas but have trouble in dim light.

Color blindness generally affects both eyes, and it typically does not get worse or better. Most people are born color-blind, but there are conditions that can cause a patient to become color-blind. As some of these conditions are serious, anybody who notices a decline in their ability to see color should talk to their ophthalmologist.

1. Macular Degeneration

Macular degeneration, which is sometimes called age-related macular degeneration (AMD) is the most common cause of vision loss in Americans over 40. The older somebody gets, the greater the chances of their developing the condition. While one in 14 people over 40 have the disease, one in three people over 80 have it.

The disease affects a part of the retina called the macula. One of the macula’s functions is to enable someone to see fine details. A person with healthy maculas can read, drive, or use a computer easily. Such tasks become increasingly difficult for a person with degenerating maculas.

Macular degeneration also causes color blindness. The macula contains more cones than any other part of the eye, so damage to the macula affects those cones. As the disease progresses, the patient loses more and more of their color vision.

By contrast, there are few or no rods in the macula, so they aren’t damaged. In fact, a patient with macular degeneration can have better night vision than somebody with normal eyes.

There are two types of macular degeneration: dry and wet. The dry form is far more common and affects around 80 percent of patients. As the patient ages, yellow protein deposits called drusen form under the retina. At the same time, the macula becomes thinner. Over time, the patient’s central vision deteriorates, while their peripheral vision remains normal.

In the wet type, new and abnormal blood vessels grow under the retina. They sometimes leak blood or other fluids and can thus scar the macula. Wet macular degeneration develops more quickly than the dry form and is thus considered more serious.