Cone cell

Cone cells, or cones, are one of the two types of photoreceptor cells that are in the retina of the eye which are responsible for color vision. They are also one of the three types of cone photoreceptor cells in the eye, the other two being rod cells and photosensitive ganglion cells.

Function

Cone cells are somewhat shorter than rods, but wider and tapered, and are much less numerous than rods in most parts of the retina, but they are the predominant type of photoreceptor in the fovea centralis, a small area in the center of the retina that is the point of sharpest vision. Humans have about 6 to 7 million cones.

Types of Cone Cells

There are three types of cone cells in the human eye. They are:

• L Cones - These are sensitive to long-wavelength light, such as red light.
• M Cones - These are sensitive to medium-wavelength light, such as green light.
• S Cones - These are sensitive to short-wavelength light, such as blue light.

Each type of cone cell responds differently to different wavelengths of light, which is how we are able to see colors.

Disorders

Disorders of the cone cells can lead to a variety of vision disorders. For example, color blindness is often caused by a defect in one or more of the types of cone cells in the eye. Other disorders that can affect the cone cells include achromatopsia, cone dystrophy, and cone-rod dystrophy.

See Also

• Photoreceptor cell
• Rod cell
• Color vision
• Color blindness
• Achromatopsia
• Cone dystrophy
• Cone-rod dystrophy

References

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  Diagram of a cone cell
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  Cone mosaics in the human retina
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  Distribution of photoreceptors in the human eye
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  Cone cells in bird retina