Crystalline lens

The transparent, flexible structure behind the iris that focuses light onto the retina. It changes shape to focus on objects at different distances.

Accommodation (eye): The process by which the eye changes optical power to focus on objects at different distances. The lens changes curvature during accommodation to bring near objects into focus.
Crystalline lens fiber: An elongated, tightly packed cell that forms the bulk of the crystalline lens. Fiber cells create the lens’s layered, transparent interior.
Presbyopia: The age-related decline in near focusing caused mainly by reduced lens flexibility. A stiffer lens becomes less able to increase its curvature for near vision.
Cornea: The transparent, curved front surface of the eye that provides most of its refractive power. The cornea supplies most fixed focusing power, while the lens adjusts focus dynamically.
Ciliary muscle: A ring of smooth muscle in the eye that changes tension on the lens-supporting zonules. Its contraction alters zonular tension and allows the lens to become rounder.
Lens epithelium: A single layer of cells on the front surface of the crystalline lens beneath its capsule. These cells maintain the lens and generate new fiber cells.
Cataract: Clouding of the crystalline lens that scatters or blocks light and impairs vision. Changes in lens proteins can make the normally transparent structure opaque.
Retina: The light-sensitive neural tissue lining the back of the eye that converts light into signals. The lens focuses light onto the retina, which detects it rather than focusing it.
Zonule of Zinn: A system of fibers connecting the ciliary body to the crystalline lens. These fibers transmit ciliary muscle forces that reshape the lens.
Refractive index gradient: A gradual change in refractive index across an optical material. The lens’s internal gradient helps focus light while reducing optical aberrations.

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