Who gets color blindness?
The majority of cases of color blindness are inherited, and the disorder is much more common among men because the inherited form of the condition is on the X chromosome. Inherited color blindness can present at birth, start during childhood, or not appear until adulthood.
Other causes of color blindness include chemical or physical damage to the eye, the optic nerve, or to parts of the brain that process color information. Cataracts can also lead to a loss of color vision.
How do we see the world in color?
In order to understand color blindness, you need a basic understanding of how color vision works:
Your brain and eyes work together to perceive the different properties of light. All objects absorb some wavelengths of light and reflect others. We perceive the reflected light as color. That means that a rose is only red because it reflects the long wavelengths of red and absorbs all the others. When an object reflects all wavelengths, you see it as white; in contrast, when it absorbs all wavelengths, you see it as black.
Photoreceptors: Rods and Cones
In order to see, light enters your eye and your cornea and lens focus it onto the retina at the back of your eye. The retina contains millions of light-sensitive cells called photoreceptors, some of which are shaped like rods and some like cones. Both rods and cones have photopigment molecules. When they absorb light, these molecules go through a chemical change that triggers electrical signals, which are then passed from the retina to the brain. Rods respond more strongly to dim light, and cones are more responsive to bright light. Also, rods contain only one photopigment and cones contain one of three different photopigments. What does this mean for your vision? In effect, cones are sensitive to red, green, and blue light wavelengths. This is what enables us to see all the rich colors of the world.
What are the different types of color blindness?
Inherited color blindness results from defects in the genes that produce the photopigments. Some of these defects alter the cone’s sensitivity to particular colors. Three types of color blindness exist:
- Red-Green Color Blindness: this is the most common type of hereditary color blindness. It is caused by the loss or limited function of red cone or green cone photopigments.
- Blue-Yellow Color Blindness: less common, this type of color blindness occurs when the blue cone photopigments have limited function or are missing altogether.
- Complete Color Blindness: called monochromacy, people with total color blindness do not see any hues. Their visual acuity may also be affected. This type of color blindness is autosomal recessive and rare.
How does our Lakeville eye doctor test for color blindness?
Color blindness detection can be done using a variety of diagnostic tests, and our Lakeville specialist is experienced in identifying this condition. Color vision testing may include:
- Ishihara Color Test – This is the most common test for red-green color blindness. Our eye doctor will show you a series of colored circles, called Ishihara plates, each of which shows a collection of dots in different sizes and colors. A shape is displayed within each circle, which is clearly visible to people with normal color vision – but if you have red-green color blindness, you won’t be able to see it.
What is the treatment for color blindness?
Color blindness has no cure, yet people with the red-green type may be able to use specialized lenses to help them perceive colors more precisely. A number of visual aids are also available, such as iPhone and iPad apps that help with distinguishing colors and shades. These forms of apps can help people to choose ripe produce in the supermarket or match complementary colors when getting dressed.
At Lakeville Family Eye Center, our eye doctor is a color blindness specialist. We will test thoroughly to detect this visual condition and assist with ways to cope during daily life tasks. For example, kids with color blindness can have trouble reading the classroom board when yellow chalk is used on a green background, or they may find art projects to be an extreme challenge. Crossing the street safely may be difficult, since a traffic light must be read by position of the light and not by color. In addition to recommending the most suitable visual aids, our eye doctor can help teach kids and adults a number of strategies that make routine activities much easier.
Book an appointment in our Lakeville office for an eye exam, which includes testing to diagnose color blindness.