night blindness

night blindness
—nightblind, adj.
Ophthalm.
a condition of the eyes in which vision is normal in daylight but abnormally poor at night or in a dim light; nyctalopia.
[1745-55]

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also called  nyctalopia  

      failure of the eye to adapt promptly from light to darkness that is characterized by a reduced ability to see in dim light or at night. It occurs as a symptom of numerous congenital and inherited retinal diseases or as a result of vitamin A deficiency.

      Congenital night blindness with or without myopia (nearsightedness) occurs either as a dominant, recessive, or sex-linked hereditary trait and usually remains stable throughout life. Night blindness developing during childhood or adolescence may be an early sign of retinitis pigmentosa, a hereditary disorder in which continued deterioration of vision—primarily because of the destruction of rod cells (visual receptors that allow vision in dim light)—often leads to significant vision impairment. Vitamin A deficiency, which causes reduced photosensitivity of rhodopsin (a chromoprotein) in rod cells, causes night blindness that is usually not severe, and vision most often recovers when adequate levels of the vitamin are administered.

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Universalium. 2010.

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Look at other dictionaries:

  • Night blindness — Night Night (n[imac]t), n. [OE. night, niht, AS. neaht, niht; akin to D. nacht, OS. & OHG. naht, G. nacht, Icel. n[=o]tt, Sw. natt, Dan. nat, Goth. nahts, Lith. naktis, Russ. noche, W. nos, Ir. nochd, L. nox, noctis, Gr. ny x, nykto s, Skr. nakta …   The Collaborative International Dictionary of English

  • night-blindness — nightˈ blindness noun Inability to see in a dim light, nyctalopia • • • Main Entry: ↑night …   Useful english dictionary

  • night blindness — n. imperfect vision in the dark or in dim light: a symptom of vitamin A deficiency …   English World dictionary

  • Night blindness — Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina. The ability of our eyes to quickly view objects as they shift from light to dark areas and the ability to see in dim …   Medical dictionary

  • night blindness — the inability to see in dim light or at night. It is due to a disorder of the cells in the retina that are responsible for vision in dim light (see rod), and can result from dietary deficiency of vitamin A. If the vitamin deficiency is allowed to …   The new mediacal dictionary

  • night blindness — night′ blind ness n. oph a condition in which vision is normal in daylight but abnormally poor in dim light • Etymology: 1745–55 night′blind , adj …   From formal English to slang

  • night blindness — noun The optic condition nyctalopia, the inability to see clearly in faint light, as at night Syn: moon blindness …   Wiktionary

  • night blindness — Synonyms and related words: Lombardy leprosy, anemia, ariboflavinosis, beriberi, cachexia, chlorosis, day blindness, deficiency anemia, dermatitis, goiter, greensickness, hemeralopia, keratomalacia, kwashiorkor, maidism, malnutrition, moon… …   Moby Thesaurus

  • night blindness — noun inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder • Syn: ↑nyctalopia, ↑moon blindness • Hypernyms: ↑visual impairment, ↑visual defect, ↑vision defect, ↑visual disorder, ↑ …   Useful english dictionary

  • night blindness — noun Date: 1754 reduced visual capacity in faint light (as at night) • night blind adjective …   New Collegiate Dictionary

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