Lens

Lens (anatomy)

The Lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina. This adjustment of the lens is known as accommodation.

Structure

The lens is a transparent biconvex structure, approximately 10 mm in diameter, located behind the iris of the eye. It is encased in a thin, transparent capsule and suspended behind the iris by a series of fibers known as the zonule of Zinn.

Function

The primary function of the lens is to focus light onto the retina. It does this by changing its shape in a process known as accommodation. When the ciliary muscle contracts, the lens becomes more spherical, increasing its power to focus incoming light. When the ciliary muscle relaxes, the lens flattens, reducing its power.

Clinical significance

Diseases of the lens are a common cause of vision problems. Cataract, a clouding of the lens, is the leading cause of blindness worldwide. Other conditions, such as presbyopia, result from loss of elasticity of the lens with age, which impairs its ability to accommodate.

See also

• Eye
• Retina
• Cornea
• Iris
• Cataract
• Presbyopia

References

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