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 ?
To focus on nearby objects, the human crystalline lens must be flexible enough to change shape by thickening at its center and change its focusing power in order to "accommodate".
It is expected that prior to treatment, the crystalline lens will swell as a result of an influx of water during long-term hyperglycaemia and lead to an increase in myopic shift.
However, it is accepted that loss of elasticity of the crystalline lens and loss of power of the ciliary muscles (the muscles which bend and straighten the lens) are involved.
The ClearPath DS-120 incorporates the use of proprietary biophotonic spectroscopy to detect autofluorescence of the crystalline lens of the eye.
Presbyopia is a vision condition in which the crystalline lens of the eye loses its flexibility, which makes it difficult to focus on close objects.
The inlay does not impair ophthalmic assessment of the eye after it has been fitted; corneal diagnostics, gonioscopy and anterior chamber angle imaging can all be achieved with the crystalline lens easily viewed through a dilated pupil, enabling assessment of lens opacities (see Figure 3).
This condition occurs when the crystalline lens of the eye loses its flexibility, making it difficult to focus on close objects.
About Presbyopia and Cataracts Presbyopia is a vision condition in which the crystalline lens of the eye loses its flexibility, which makes it difficult to focus on close objects.
He observed that for focusing on near objects, the contraction of the ciliary muscle allows a relaxation of the zonular fibres and consequently, a bulging of the crystalline lens.
Lenstatin (TM) is the world's first proprietary formulated nutritional supplement containing 11 micronutrients and anti-oxidants which are targeted to support the health of the human crystalline lens in patients with early cataracts.
Crystalline lens transparency can be significantly reduced in CF patients, with the greatest reduction in transparency seen in those with more severe digestive insufficiency.
The Superfocus technology will provide unparalleled clear vision to astronauts with presbyopia, a condition caused by aging in which the eye's crystalline lens becomes increasingly inflexible, making it difficult to focus on nearby objects.