trifocal lenses

trifocal lenses
lenses in which there are three segments. The upper provides a clear image of distant objects; the lower is used for reading and close work; and the middle one for the intermediate distance. Musicians sometimes find the middle segment useful for reading the score during performance.

Medical dictionary. 2011.

Look at other dictionaries:

  • trifocal lenses — lenses in which there are three segments. The upper provides a clear image of distant objects; the lower is used for reading and close work; and the middle one for the intermediate distance. Musicians sometimes find the middle segment useful for… …   The new mediacal dictionary

  • Линзы Трифокальные (Trifocal Lenses) — линзы, состоящие из трех сегментов. Верхний сегмент позволяет четко видеть удаленные от глаз предметы; нижний используется во время чтения и работы вблизи, а средний для рассмотрения предметов, находящихся на среднем от глаз расстоянии. Музы… …   Медицинские термины

  • Trifocal — Trifocals are eyeglasses where the lenses have 3 regions to correct for distance, intermediate (arm s length), and near vision. They are mostly used by people with advanced presbyopia who have been prescribed 2 diopters or more of reading… …   Wikipedia

  • trifocal — Having three foci. See t. lens. * * * tri·fo·cal ( )trī fō kəl adj 1) having three focal lengths 2) of an eyeglass lens having one part that corrects for near vision, one for intermediate vision (as at arm s length), and one for distant vision… …   Medical dictionary

  • trifocal — I. adjective Date: 1826 having three focal lengths II. noun Date: 1899 1. plural eyeglasses with trifocal lenses 2. a trifocal glass or lens …   New Collegiate Dictionary

  • trifocal — /truy foh keuhl, truy foh /, adj. 1. Optics. having three foci. 2. (of an eyeglass lens) having three portions, one for near, one for intermediate, and one for far vision. n. 3. trifocals, eyeglasses with trifocal lenses. [1945 50; TRI + FOCAL] * …   Universalium

  • trifocal glasses — glasses with trifocal lenses …   Medical dictionary

  • trifocal — tri•fo•cal [[t]traɪˈfoʊ kəl, ˈtraɪˌfoʊ [/t]] adj. 1) opt (of a lens) having three foci 2) (of an eyeglass lens) having three portions, one for near, one for intermediate, and one for far vision 3) trifocals, eyeglasses with trifocal lenses •… …   From formal English to slang

  • trifocal — adjective (of a pair of glasses) having lenses with three parts with different focal lengths. noun (trifocals) a pair of trifocal glasses …   English new terms dictionary

  • trifocal — adjective Of or pertaining to corrective lenses that have three different powers per eye. See Also: bifocal, trifocals …   Wiktionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”