Color blindness usually affects a person’s ability to tell the difference between shades of red and green or shades of blue and yellow. Complete color blindness, which is rare, causes a person to see most objects in shades of gray.

Color blindness occurs when light-sensing receptors in the eye do not work properly.

Most color blindness is inherited. Less frequently, color blindness is caused by a disease that affects the optic nerve or retina. This is referred to as acquired color blindness.

Anatomy of the Eye
Normal Anatomy of the Eye
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