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 ?
* Contact sports--direct contact to the globe during a physical activity may cause the implant to become displaced or come in to contact with the natural crystalline lens, which can increase the chance of a cataract.
This can lead to a misdiagnosis of crystalline lens luxation, especially when conditions for peripheral retinal examination are not ideal.
However, given the yearly increase in crystalline lens rise and the young age of the patients, we believe that it is advisable to be as close to 250 p as possible.
A cataract is a clouding that develops in the crystalline lens or in the cornea.
(Having astigmatism, dry eyes, or thin eye coverings are common disqualifiers.) For some, however, newer implantable contact lenses (ICLs), or Visian lenses, that surgeons place in front of the eye's natural crystalline lens may be an even better choice.
In addition to very loud noises, tinnitus is caused by use of cell phones, iPods and MP3 players, while presbyopia is a natural result of aging as the crystalline lens of the eye loses its flexibility.
As we age, the crystalline lens, which sits behind the cornea and acts like a zoom, stiffens from a squashy gel-like substance to a fixed structure," the Daily Mail quoted him as saying.
Many patients do not actually know that a cataract is a clouding of the crystalline lens of the eye preventing light rays from passing through it easily.
Difficulties while working with close objects are caused by the loss of the crystalline lens flexibility and elasticity, and as a result it starts to adapt slowly (this process resembles a camera, where auto-focus function is disrupted and it no longer focuses sharpness).
the orbit," the sparkle the warning the crystalline lens has
Glutathione levels of the human crystalline lens in aging and its antioxidant effect against the oxidation of lens proteins.