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The surface of the human retina contains about 6 million cones and 100 million rods. Cones transmit color information; rods focus on greater sensitivity to low-light conditions. The fovea is the retina's center, predominately concentrated with cones to accommodate high visual acuity in high-light conditions. Photon-powered isomerization of rhodopsin, a complex consisting of vitamin-A-derived retinal and the protein opsin, is the molecular mechanism of action for retina cells (photoreceptors).[1][2][3]

Color blindness is a group of eye disorders that affect the perception of color. The most common color vision deficiency is a red-green color vision. Affected individuals often have difficulty differentiating between yellow, red, and green shades. Blue-yellow color vision defects are rare. Color vision problems can also be due to medications, chemical exposure, and old age. Once diagnosed, there is no cure for inherited color deficiency, but those related to medications, injury, or illness can be improved. Thus, besides the ophthalmologist, the nurse and pharmacist must know color vision defects and their causes. Any drug known to affect color vision should be discontinued. The patient should be referred to the ophthalmologist or optometrist for specially designed eyeglasses or red-tinted contact lenses.[15] Outcomes Color vision deficiency may limit jobs in certain professions, but the condition is not life-threatening. While the Occupational and Safety Health Administration neither precludes employers from requiring normal vision for essential job duties nor requires employers to maintain a color-blind, aware environment, the organization has deferred to the society standards of specific professions. For example, the standard American Society of Mechanical Engineers B30.2-2001, Overhead, and Gantry Cranes, requires that operators of cab-operated and pulpit-operated cranes be able to distinguish between colors if such is needed for proper equipment operation. The recent availability of tinted lenses and glasses has allowed most people to adapt to various deficits. Gene therapy may be available to restore vision in those with hereditary disorders of colored vision deficiency.[16][17][3]