Screening tests help detect colorblindness; however earlier symptoms include an apparent difficulty learning some or all of the colors.
Is it contagious?
How long does it last?
This is generally a lifelong condition.
How is it diagnosed?
Colorblindness is usually tested at children's four-year physicals. The doctor asks them to identify a red and a green line on the eye chart. If any question remains, more precise visual testing can determine the exact nature of the problem.
How is it treated?
There is no known way to restore color vision in those who have hereditary colorblindness. By being aware of their condition, we can help our children learn other ways to distinguish between red and green -- the position of traffic lights, for instance. In addition, we can decorate their worlds, and wrap their presents, in the millions of nuances of color that are still available to them.
How can it be prevented?
There is no practical way to prevent color blindness.
People with cerebral achromatopsia do not have any defects with the cones in their eyes. Unlike congenital colorblindness, they can see objects as gray because prior to the trauma or illness, they understood what color was.
People with cerebral achromatopsia are perfectly aware of their visual experiences; however, they are unable to imagine or remember colors. They see the world like a big black and white television where everything is a shade of gray. They cannot chromatically order or discriminate hue but they can distinguish color contrast like a normal person.
Below is a picture illustrating what a person with brain damage to both sides, bilateral, achromatopsia would see compared to a person with normal vision.
The primary visual cortex in the occipital lobe interprets the signals that come from the eye. Within the occipitotemporal junction, the color remembering and imaging center is located in the V4-lingual and fusiform gyri (bumps on the brain). Below are two pictures that illustrate the different parts of the brain. The part of the brain closest to you in yellow picture is the back of the head, where the visual cortex is. The second photo is a side view of the relative areas of the head that relate to specific functions.
The two graphics below illustrate what a person who has hemiachromatopsia would see.