contact lens (redirected from contacts)

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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contact lens

n.

A thin plastic or glass lens that is fitted over the cornea of the eye to correct various vision defects.

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contact lens,

a small, curved lens, primarily plastic in composition, shaped to fit the person's eye either to correct refractive error or to enhance appearance. The two primary forms of contact lenses are (1) rigid gas-permeable lenses, which are small, are durable, and have little to no water absorption; and (2) soft lenses, which are larger, are more fragile, and have a 30% to 70% water content. Contact lenses float on the precorneal tear film and must be inserted, removed, cleaned, and stored to prevent damage or infection to the eyes. Patients should not sleep with their lenses in their eyes.

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contact lens

Ophthalmology Crystalline ocular lens A transparent soft or rigid device placed directly on the cornea to correct refractory errors

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Patient discussion about contacts.

Q. Contact lenses I’m 17 years old girl, and I have glasses since third grade. I never had any real problems with wearing them,. my best friend always encourage me to try contact lenses, but it seems so strange to put something on directly on your eyes- is it safe? How difficult is it to do?

A. Consult your ophthalmologist (eye doctor) before you decide.

Q. My contact lenses get very dry and it hurts. any suggestions?

A. Dry contact may signal they should be replaced with new ones, and pain may result from damage to the lenses (e.g. torn lens- VERY VERY hurts). However, as much as I would like to help you, it's just impossible to give you the correct diagnosis over the net without even looking at your eyes. So if you feel any problems with your eyes, ophthalmologist (eye doctor would be the answer).

Meanwhile, you may read more here:http://www.nlm.nih.gov/medlineplus/eyewear.html