- trifocal lens
- a lens that has three segments with different refractive powers, ordinarily with the upper for distant, the middle for intermediate, and the lower for near vision; used in trifocal glasses.
Medical dictionary. 2011.
trifocal lens
Look at other dictionaries:
trifocal — ☆ trifocal [trī fō′kəl; ] also, and for n. usually [, trī′fō΄kəl ] adj. adjusted to three different focal lengths n. a lens like a bifocal but with an additional narrow area ground to adjust the intermediate focus for objects at c. 76 cm ( c. 30… … English World dictionary
Lens — The transparent structure inside the eye that focuses light rays onto the retina (the nerve layer that lines the back of the eye, senses light and creates impulses that go through the optic nerve to the brain). The lens was named after the lentil … Medical dictionary
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 — 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 — 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 — adj. & n. adj. having three focuses, esp. of a lens with different focal lengths. n. (in pl.) trifocal spectacles … Useful english dictionary
lens — n. 1) (in anatomy) the transparent crystalline structure situated behind the pupil of the eye and enclosed in a thin transparent capsule. It helps to refract incoming light and focus it onto the retina. See also: accommodation 2) (in optics) a… … The new mediacal dictionary
trifocal — adj. concerning an eyeglass lens with three portions (for seeing far, intermediate and near); having three focal lengths … English contemporary dictionary
lente trifocal — Eng. Trifocal lens Lente con tres focos destinados para la visión lejana, intermedia y próxima … Diccionario de oftalmología
