Lens (redirected from intumescent lens)

lens (lenz)

1. a piece of glass or other transparent material so shaped as to converge or scatter light rays; see also glasses.

Lenses: (A–F), Spherical lenses: (A), biconvex; (B), biconcave; (C), planoconvex; (D), planoconcave; (E), concavoconvex, periscopic convex, converging meniscus; (F), convexoconcave, periscopic concave, diverging meniscus; (G, H), cylindrical lenses, concave and convex.

2. crystalline l.; the transparent, biconvex body separating the posterior chamber and vitreous body, and constituting part of the refracting mechanism of the eye.

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achromatic lens  one corrected for chromatic aberration.

aplanatic lens  one for correcting spherical aberrations.

bandage lens  a soft contact lens worn on a diseased or injured cornea to protect or treat it.

biconcave lens  one concave on both faces.

biconvex lens  one convex on both faces.

bifocal lens  one with two parts of different refracting powers, the upper for distant and the lower for near vision.

concavoconvex lens  one with one concave and one convex face.

contact lens  a curved shell of glass or plastic applied directly over the globe or cornea to correct refractive errors. It may be a soft (hydrophilic) contact l., flexible and water absorbent, or a hard (hydrophobic) contact l., rigid and not water absorbent; the latter type is subdivided into gas permeable and non–gas permeable, usually polymethylmethacrylate (PMMA), lenses.

convexoconcave lens  one with one convex and one concave face.

crystalline lens  lens (2).

cylindrical lens  one for correcting astigmatism, with one plane surface and one cylindrical, or one spherical surface and one toroidal. Symbol C.

decentered lens  one whose optical axis does not pass through the center.

honeybee lens  a magnifying lens resembling the multifaceted eye of the honeybee, consisting of three or six small telescopes mounted in the upper part of the lens and 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 of bifocal and trifocal lenses.

planoconvex lens  a lens with one plane and one convex side.

spherical lens  (S) (sph) one that is a segment of a sphere.

trial lens  one used to test vision.

trifocal lens  one with three parts of different refracting powers, the upper for distant, the middle for intermediate, and the lower for near vision.

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lens (lnz) n. pl. lens·es 1. A ground or molded piece of glass, plastic, or other transparent material with opposite surfaces either or both of which are curved, by means of which light rays are refracted so that they converge or diverge to form an image. 2. A transparent, biconvex body of the eye between the iris and the vitreous humor that focuses light rays entering through the pupil to form an image on the retina. lensed adj.

lens Light passing through double-convex lens (top) and double-concave lens. In each drawing, f indicates focus.

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Lens (the crystalline lens)

The transparent, elastic, curved structure behind the iris (colored part of the eye) that helps focus light on the retina.

Mentioned in: Eye Glasses and Contact Lenses, Glaucoma, Myopia, Presbyopia

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Lens

includes L. culinaris, L. esculenta. See ervum.

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lens

1. a piece of glass or other transparent material so shaped as to converge or scatter light rays.

2. crystalline lens; the transparent, biconvex body separating the posterior chamber and the vitreous body of the eye. The crystalline lens refracts (bends) light rays so that they are focused on the retina. 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. See also lenticular.

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apochromatic lens

one corrected for both chromatic and spherical aberration.

biconcave lens

one concave on both faces.

biconvex lens

one convex on both faces.

lens cells

the only nucleated cells in the lens of the adult are those of the epithelium beneath the capsule on the rostral surface.

concave lens

one with one or both (biconvex) faces curved like a section of the interior of a hollow sphere; it disperses light rays. Called also dispersing lens.

contact l's

lenses that fit directly over the cornea of the eye; used in humans for correction of refractive errors but only rarely applied in animals and then for therapeutic purposes. They can be applied in cases of severe bullous keratopathy or, after saturation with antibiotic solution, the delivery of antibiotics in high concentration to the cornea.

converging lens

one curved like the exterior of a hollow sphere; it brings light to a focus. Called also convex lens.

convex lens

see converging lens (above).

convexoconcave lens

one that has one convex and one concave face.

crystalline lens

see lens (2) (above).

dispersing lens

concave lens.

ectopic lens

see ectopia lentis.

lens fibers

elongated, modified cells oriented meridianly in concentric layers; the most peripheral contain nuclei; they interlock with each other via the medium of ball and socket interdigitations and flaps and imprints.

lens-induced uveitis

see phacolytic uveitis, phacoclastic uveitis.

lens induction

see inductive interactions.

intraocular lens

plastic lenses placed within the lens capsule after cataract surgery.

intumescent lens

see intumescent cataract.

lens luxation

separation of the lens from its zonular attachments, allowing displacement and freedom to move in the posterior chamber, anterior chamber or occasionally the vitreous. Occurs most commonly in dogs and is a result of trauma or as a familial trait, particularly in wirehaired Fox terriers and Sealyham terriers, predisposing to glaucoma. Luxation can occur secondary to space-occupying intraocular tumors, enlargement of the globe in chronic glaucoma, or swelling of the lens as seen in intumescent cataract.

Lens luxation in a horse's eye. By permission from Knottenbelt DC, Pascoe RR, Diseases and Disorders of the Horse, Saunders, 2003

lens opacity

cataract.

lens sclerosis

see nuclear sclerosis.

lens subluxation

partial separation of zonular attachments, allowing some alteration in position but not movement into another chamber.

lens sutures

structures formed by the contact between caudal and rostral lens fibers resulting in Y-shaped lens stars.