What does night blindness mean?

Definitions for night blindness
night blind·ness

This dictionary definitions page includes all the possible meanings, example usage and translations of the word night blindness.

Princeton's WordNet

  1. nyctalopia, night blindness, moon blindnessnoun

    inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder


  1. night blindnessnoun

    The optic condition nyctalopia, the inability to see clearly in faint light, as at night


  1. night blindness

    Nyctalopia (; from Ancient Greek νύκτ- (núkt-) 'night', ἀλαός (alaós) 'blind, invisible', and ὄψ (óps) 'eye'), also called night-blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition (for example, vitamin A deficiency). It can be described as insufficient adaptation to darkness. The most common cause of nyctalopia is retinitis pigmentosa, a disorder in which the rod cells in the retina gradually lose their ability to respond to the light. Patients with this genetic condition have progressive nyctalopia and eventually, their daytime vision may also be affected. In X-linked congenital stationary night blindness, from birth the rods either do not work at all, or work very little, but the condition does not get worse. Another cause of night blindness is a deficiency of retinol, or vitamin A1, found in fish oils, liver and dairy products. The opposite problem, the inability to see in bright light, is known as hemeralopia and is much rarer. Since the outer area of the retina is made up of more rods than cones, loss of peripheral vision often results in night blindness. Individuals with night blindness not only see poorly at night but also require extra time for their eyes to adjust from brightly lit areas to dim ones. Contrast vision may also be greatly reduced. Rods contain a receptor-protein called rhodopsin. When light falls on rhodopsin, it undergoes a series of conformational changes ultimately generating electrical signals which are carried to the brain via the optic nerve. In the absence of light, rhodopsin is regenerated. The body synthesizes rhodopsin from vitamin A, which is why a deficiency in vitamin A causes poor night vision. Refractive "vision correction" surgery (especially PRK with the complication of "haze") may rarely cause a reduction in best night-time acuity due to the impairment of contrast sensitivity function (CSF) which is induced by intraocular light-scatter resulting from surgical intervention in the natural structural integrity of the cornea.


  1. night blindness

    Night blindness, also known as nyctalopia, is a type of vision impairment characterized by difficulty seeing in dark or low-light conditions. It is often caused by certain eye diseases or conditions that result in a decreased production of the pigment needed for seeing at night. It's not a disease in itself, but rather a symptom of underlying problems, such as Vitamin A deficiency or specific eye conditions like retinitis pigmentosa. It can make tasks such as driving at night difficult and dangerous.

U.S. National Library of Medicine

  1. Night Blindness

    Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)

How to pronounce night blindness?

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  1. Chaldean Numerology

    The numerical value of night blindness in Chaldean Numerology is: 4

  2. Pythagorean Numerology

    The numerical value of night blindness in Pythagorean Numerology is: 3

Translations for night blindness

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"night blindness." Definitions.net. STANDS4 LLC, 2024. Web. 27 May 2024. <https://www.definitions.net/definition/night+blindness>.

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