Achromatopsia: defective ability to see colors
Tetrachromacy: quality of having four independent channels for conveying color information in the eye
Dichromic: a deficiency of color vision in which the person can match any given hue by mixing only two other wavelengths of light (as opposed to the three wavelengths needed by people with normal color vision)
Retina: the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve
Rods: are most sensitive to light and dark changes, shape and movement and contain only one type of light-sensitive pigment. Rods are not good for color vision [1]
Cones: not as sensitive to light as the rods. However, cones are most sensitive to one of three different colors (green, red or blue). Signals from the cones are sent to the brain which then translates these messages into the perception of color. Cones, however, work only in bright light.[2]
X-linked trait: are traits that are passed on from parents to offspring on the X chromosome (the chromosome related to gender)[3]
Colorblind: Having a less than normal ability to distinguish colors. There are several different forms of this usually genetic condition, and different forms determine which colors are indistinguishable.
Color vision deficiency: genetic inability to distinguish differences in hue
Sex-linked recessive traits: Recessive inheritance is when both matching genes must be abnormal to cause disease. If only one gene in the pair is abnormal, the disease does not occur, or is mild. Someone who has one abnormal gene (but no symptoms) is called a carrier. A carrier can pass this abnormal gene to his or her children.[4]
Monochromatic: complete color blindness; colors can be differentiated only on the basis of brightness
[1] http://faculty.washington.edu/chudler/retina.html
[2] http://faculty.washington.edu/chudler/retina.html
[3] http://library.thinkquest.org/C0110254/Xlink.html
[4] http://www.nlm.nih.gov/medlineplus/ency/article/002051.htm
Tetrachromacy: quality of having four independent channels for conveying color information in the eye
Dichromic: a deficiency of color vision in which the person can match any given hue by mixing only two other wavelengths of light (as opposed to the three wavelengths needed by people with normal color vision)
Retina: the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve
Rods: are most sensitive to light and dark changes, shape and movement and contain only one type of light-sensitive pigment. Rods are not good for color vision [1]
Cones: not as sensitive to light as the rods. However, cones are most sensitive to one of three different colors (green, red or blue). Signals from the cones are sent to the brain which then translates these messages into the perception of color. Cones, however, work only in bright light.[2]
X-linked trait: are traits that are passed on from parents to offspring on the X chromosome (the chromosome related to gender)[3]
Colorblind: Having a less than normal ability to distinguish colors. There are several different forms of this usually genetic condition, and different forms determine which colors are indistinguishable.
Color vision deficiency: genetic inability to distinguish differences in hue
Sex-linked recessive traits: Recessive inheritance is when both matching genes must be abnormal to cause disease. If only one gene in the pair is abnormal, the disease does not occur, or is mild. Someone who has one abnormal gene (but no symptoms) is called a carrier. A carrier can pass this abnormal gene to his or her children.[4]
Monochromatic: complete color blindness; colors can be differentiated only on the basis of brightness
[1] http://faculty.washington.edu/chudler/retina.html
[2] http://faculty.washington.edu/chudler/retina.html
[3] http://library.thinkquest.org/C0110254/Xlink.html
[4] http://www.nlm.nih.gov/medlineplus/ency/article/002051.htm