Color blindness in adults affects less than one percent of women and seven percent of men, however, not everyone's sight is affected in the same way. Some people can see colors, but have difficulty distinguishing between them, while others have problems telling the difference between blues and yellows or reds and greens. The most common problem with color blindness is distinguishing between reds and greens. A small number of people who have more serious problems with color blindness only see in gray hues or in black and white.

One symptom of color blindness in adults is when a person is not able to see colors and their brightness in the normal way. Another problem is the inability to tell the difference between shades of the same color or similar colors. When a person experiences fast side-to-side eye movements, it means that the color blindness is much more serious, and this person may be one who only sees in black and white or in gray.

The most common eye screening test that doctors use to check for color blindness is called the Ishihara Color Vision Test. This test is made up of several pages put together in booklet form, and each page has a circle that is made up of different sized and different colored dots. Within each circle there is either a single digit number or a double digit number made up of a different color that a person with normal vision can see quite easily. A person who is colorblind cannot see the number.

The Farnsworth-Munsell 100 Hue Test is the most popular quantitative color blind test. It shows whether or not a person can accurately perceive colors. This test has four trays and each tray has numerous small disks of varying hues of a color. When a person is being tested, they must put the disks in order according to the gradually changing hues. The ideal testing location for the Hue Test is in a small booth that has light as close to natural daylight as possible. Each small disk has a number printed on the bottom to make scoring easy. The eye doctor can tell the degree of color blindness and its severity according to whether or not the disks are placed in the correct order.

The Cambridge Color Test is a newer test that is similar to the Ishihara pages, but these designs are shown on a computer monitor. The person being tested is asked to identify the large C that is a different color from the background. He is shown four different pictures and must press the key that corresponds to the picture that has the large C.