crystalline lens


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Related to crystalline lens: lens subluxation

lens

 [lenz]
1. a piece of glass or other transparent material so shaped as to converge or scatter light rays. See also glasses.
2. the transparent, biconvex body separating the posterior chamber and the vitreous body of the eye; it refracts (bends) light rays so that they are focused on the retina. Called also crystalline lens. In order for the eye to see objects close at hand, light rays from the objects must be bent more sharply to bring them to focus on the retina; light rays from distant objects require much less refraction. It is the function of the lens to do accommodation, making of adjustments for viewing both near objects and more distant ones. To accomplish this it must be highly elastic so that its shape can be changed and made more or less convex. The more convex the lens, the greater the refraction. Small ciliary muscles create tension on the lens, making it less convex; as the tension is relaxed the lens becomes more spherical in shape and hence more convex.

With increasing age the lenses lose their elasticity; thus their ability to focus light rays in the retina becomes impaired. This condition is called presbyopia. In farsightedness (hyperopia) the image is focused behind the retina because the refractive power of the lens is too weak or the eyeball axis is too short. Nearsightedness (myopia) occurs when the refractive power of the lens is too strong or the eyeball is too long, so that the image is focused in front of the retina.
The biconvex lens of the eye. From Frazier et al., 1996.
achromatic lens one corrected for chromatic (color) aberration.
apochromatic lens one corrected for chromatic (color) and spheric aberration.
biconcave lens one concave on both faces.
biconvex lens one convex on both faces.
bifocal lens one having two segments with different refracting power, the upper for far vision and the lower for near vision. See also bifocal glasses.
concave lens one curved like a section of the interior of a hollow sphere; it disperses light rays. Called also diverging lens.
contact l's corrective lenses that fit directly over the cornea of the eye; see also contact lenses.
converging lens (convex lens) one curved like the exterior of a hollow sphere; it brings light to a focus.
convexoconcave lens one that has one convex and one concave face.
crystalline lens lens (def. 2).
cylindrical lens one with at least one nonspherical surface, used to correct astigmatism.
diverging lens concave lens.
honeybee lens a magnifying eyeglass lens designed to resemble the multifaceted eye of the honeybee. It consists of three or six small telescopes mounted in the upper portion, directed toward the center and right and left visual fields. Prisms are included to provide a continuous, unbroken magnified field of view.
omnifocal lens one whose power increases continuously and regularly in a downward direction, avoiding the discontinuity in field and power inherent in bifocal and trifocal lenses.
orthoscopic lens one that gives a flat and undistorted field of vision, especially at the periphery.
planoconcave lens a lens with one plane and one concave side.
planoconvex lens a lens with one plane and one convex side.
Stokes's l's an apparatus used in the diagnosis of astigmatism.
trial l's ones used in testing the vision.
trifocal lens one having three segments of different refracting powers, the upper for distant, the middle for intermediate, and the lower for near vision.

lens

(lenz), [TA] Avoid the misspelling lense.
1. A transparent material with one or both surfaces having a concave or convex curve; acts on electromagnetic energy to cause convergence or divergence of light rays.
2. The transparent biconvex cellular refractive structure lying between the iris and the vitreous humor, consisting of a soft outer part (cortex) with a denser part (nucleus), and surrounded by a basement membrane (capsule); the anterior surface has a cuboidal epithelium, and at the equator the cells elongate to become lens fibers. Synonym(s): crystalline lens
[L. a lentil]

crystalline lens

n.
The lens of the eye in vertebrates and certain invertebrates.

crystalline lens

The internal, fine-focusing, lens of the eye, which lies immediately behind the iris diaphragm and is suspended by a delicate ligament from the CILIARY BODY. In youth the lens is elastic and changes shape easily. Elasticity, and range of focusing power, fall off almost linearly with age.

Lens (or crystalline lens)

The eye structure behind the iris and pupil that helps focus light on the retina.
Mentioned in: Presbyopia

Patient discussion about crystalline lens

Q. My neighbor's kid had a lens dislocation due to Marfan's disease. Is this a contagious thing? My neighbor's have a sweet 8 year old boy. he had a lens dislocation due to a connective tissue disease named Marfan (I think that the name). It sounds like a very serious condition. My boy is playing with this kid several hour a week. should I take him to the GP to see that his is not infected with this marfan thing?

A. As in love and war so is in medicine the is no always nor never. It is probably the marfan that caused your neighbor kid the lens dislocation but you can never know for sure.
If you want there is nothing wrong in taking your boy for an annual check of an ophthalmologist.

More discussions about crystalline lens
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.
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.
Statins, widely prescribed to lower LDL ("bad") cholesterol and protect hearts, appear to offer protection against the most common kind of age-related cataract, clouding in the center of the crystalline lens of the eye.
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.
Disease or damage to the cornea and crystalline lens typically reduces acuity.
I went back to reading the paper; gobs of offal prose from Elliott Abrams, forming by reflected light an image subsequently focused by cornea, aqueous humor, crystalline lens, vitreous humor and retina, thence passed into the occipital area of the brain for analysis and subsequent storage next to reveries of childhood, old recipes and some lines from Empson's poem "Missing Dates": "Slowly the poison the whole blood stream fills/di dum di dum/the waste remains, the waste remains and kills." The bright side: This isn't Chile.