Crystalline Lens


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crystalline lens

[′kris·tə·lən ′lenz]
(anatomy)

Crystalline Lens

 

a lenticular transparent body (convex lens) of the eye located behind the iris and opposite the pupil; part of the light-refractive (dioptric) system of the eye in vertebrates, including humans. The crystalline lens is divided structurally into the anterior epithelium of the cornea and the body, which consists of fibers and intercellular cementing substances. Externally it is clad in a capsule—an elastic membranous envelope. The lens has anterior and posterior surfaces, with corresponding anterior and posterior poles through which the optical axis of the eye passes. The maximum circumference on the lateral surface in a plane perpendicular to the optical axis is called the equator of the lens.

The annular Zinn’s ligament is attached to the capsule at the equator; change in its tension changes the curvature of the lens surface, as a result of which accommodation is effected in higher vertebrates. In fishes and amphibians the lens is suspended by a ligament and during accommodation moves away from or toward the retina by means of a special muscle. In embryonic development the lens is formed from the covering epithelium under the inductive influence of the eye rudiment. Water constitutes about 65 percent of the lens, and proteins 35 percent. The crystalline lens of vertebrates grows throughout life. With age the lens scleroses, and there is a consequent weakening of accommodation (presbyopia). The most common pathological change in the lens is opacification, that is, the formation of cataracts.

O. G. STROEVA

References in periodicals archive ?
TRP's Blur Relief eye drops are formulated to stimulate the body to provide nutrients and oxygen to the crystalline lens, improving its flexibility and reducing blurry vision.
Glutathione levels of the human crystalline lens in aging and its antioxidant effect against the oxidation of lens proteins.
This must have been far from easy, since in the final section, "A Vast Reader," Carneci calls for a remote polymath to "encompass in the dazzling crystalline lens of his single, all-embracing eye" everything in the universe, past, present, and future.
To treat presbyopia, some surgeons have begun replacing the natural crystalline lens with implantable, variable-focus lenses that correct for near, distance and/or intermediate vision.
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What happens: The crystalline lens in the eye becomes cloudy.
Fibres in the crystalline lens in the eye harden up when we start to approach mid to late forties,' Ms Clark said.
Presbyopia is a condition in which the crystalline lens of the eye loses its flexibility.
When you hit your 40s, the crystalline lens [in the eye] cannot change focus quite as readily," McNally explains.
Cataract, which is cloudiness of an eye's crystalline lens, is the leading cause of vision loss among older adults.
Disease or damage to the cornea and crystalline lens typically reduces acuity.