Lens (vision) - Definition and Overview

Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens.

The lens or crystalline lens is a component of the eye. In concert with the cornea, it refracts light, focussing it onto the retina.

The lens is clear and flexible; its curvature is controlled by ciliary muscles. By changing the curvature of the lens, one can focus the eye on objects at different distances from it.

The lens is about 5 mm wide and has a diameter of about 9 mm for an adult human (though these figures can vary). The lens is included into the capsular bag, maintained by the zonules of Zinn.

Diseases of the eye

• A cataract is when the normally transparent crystalline lens develops opacities and leads to blurry vision.

See also

• visual perception
• eye
• iris
• lens (optics)
• intraocular lens
• capsular bag
• capsulorhexis
• phacoemulsification
• zonules of Zinn
• aphakia, the absence of the natural crystalline lens of the eye.

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