Color blindness

Inability of the eye to distinguish particular color combinations.

Estimated 10 million men, about 7% of male population in the US.

As many as 8% of men and 1% of women have some degree of color blindness.

Red–green color blindness is an X-linked recessive disorder.



Between seven and ten percent of men and 0.49% to 1% of women are affected by red-green color blindness.

The retina transmits light signals to the optic nerve, which in turn, conveys information to the brain where a visual image is perceived.

The retinal contains two types of light sensing neurons: rod photoreceptors and cone receptors.

Rod receptors respond to dim light, while cone photoreceptors respond to bright light.

Vision begins with light absorption of light by visual pigments in these photoreceptors.

Cone photoreceptors carry one of three different pigments which are maximally sensitive at long, middle, and short wave lengths, or red, green and blue, respectively.

Individuals with all three pigments are referred to as trichromats.

The absorption spectrum of the three pigments cover the visible soectrum.

Color blindness is a result of of loss or modification in one of the three different cone pigments.

Results from loss or modification of one or more cone photoreceptors carrying pigment.

Most commonly a loss of one opsin cone photoreceptor usually in the long or middle wavelength exists in color blindness.

Dichromats, individuals with 2 cone opsins have normal vision, full vision fields, normal sensitivities to white light.

Dichromats have difficulty with color identification in daily activities anf function.

Leave a Reply

Your email address will not be published. Required fields are marked *