Lens - Definition

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The lens, located in the eyeball, is a key element of vision. It is a kind of bi-convex lens which enables adaptation: by varying the radius of curvature, the lens allows the eye to adapt its vision to different distances and to generate clear images. With age, the lens may lose its flexibility and become deformed, causing presbyopia, or gradually become opaque: these are cataracts which can lead to blindness, but surgery which replaces the opaque lens with an implant is frequent and effective.