| 释义 |
dark adaptation
dark adaptationn. The physical and chemical adjustments of the eye, including dilation of the pupil and increased activity of rods in the retina, that make vision possible in relative darkness.
dark′-a·dapt′ v.dark′-a·dapt′ed (-ə-dăp′tĭd) adj.dark′ adapta`tion
n. the reflex adjustment of the eye to dim light or darkness, consisting of a dilation of the pupil, an increase in the number of functioning rods, and a decrease in the number of functioning cones. [1905–10] dark′-a•dapt`ed, adj. Thesaurus| Noun | 1. | dark adaptation - the process of adjusting the eyes to low levels of illumination; cones adapt first; rods continue to adapt for up to four hoursadaptation - (physiology) the responsive adjustment of a sense organ (as the eye) to varying conditions (as of light) |
dark adaptation
dark adaptationThe process by which the iris and the retina of the eye adjust to allow maximum vision in dim illumination following exposure of the eye to a relatively brighter illumination. In darkness, vision becomes more sensitive to light, provided a person has not been exposed to bright light for some time. Although exposure to total darkness for at least 30 minutes is required for complete dark adaptation, a pilot can achieve a moderate degree within 20 minutes under dim red cockpit lighting. Dark adaptation is impaired by exposure to cabin pressure altitudes above 5000 ft, carbon monoxide inhaled in smoking and from exhaust fumes, deficiency of vitamin A in the diet, and prolonged exposure to bright sunlight.dark adaptation
adaptation [ad″ap-ta´shun] 1. a dynamic, ongoing, life-sustaining process by which living organisms adjust to environmental changes.2. adjustment of the pupil to light.biological adaptation the adaptation of living things to environmental factors for the ultimate purpose of survival, reproduction, and an optimal level of functioning.color adaptation 1. changes in visual perception of color with prolonged stimulation.2. adjustment of vision to degree of brightness or color tone of illumination.dark adaptation adaptation of the eye to vision in the dark or in reduced illumination.light adaptation adaptation of the eye to vision in the sunlight or in bright illumination (photopia), with reduction in the concentration of the photosensitive pigments of the eye.physiological adaptation the ongoing process by which internal body functions are regulated and adjusted to maintain homeostasis in the internal environment.psychological adaptation the ongoing process, anchored in the emotions and intellect, by which humans sustain a balance in their mental and emotional states of being and in their interactions with their social and cultural environments.social adaptation adjustment and adaptation of humans to other individuals and community groups working together for a common purpose.dark ad·ap·ta·tionthe visual adjustment occurring under reduced illumination in which the retinal sensitivity to light increases.
See also: dark-adapted eye, Purkinje shift. Synonym(s): scotopic adaptationdark adaptationn. The physical and chemical adjustments of the eye, including dilation of the pupil and increased activity of rods in the retina, that make vision possible in relative darkness.
dark′-a·dapt′ v.dark′-a·dapt′ed (-ə-dăp′tĭd) adj.dark ad·ap·ta·tion (dahrk ad'ap-tā'shŭn) The visual adjustment occurring under reduced illumination in which the retinal sensitivity to light is increased.
See also: dark-adapted eye
Synonym(s): scotopic adaptation. dark adaptation The gradual acquisition of the ability to see in dim light that normally occurs in conditions of poor illumination. Dark adaptation becomes defective (night blindness) in vitamin A deficiency because this vitamin is necessary for the production of retinal VISUAL PURPLE. Poor dark adaptation is also a feature of RETINITIS PIGMENTOSA (tapetoretinal degeneration).dark adaptation the increase in light sensitivity of an eye as a result of remaining in the dark, being the time taken for rods to re-form rhodopsin. In total darkness it takes 30 minutes for the rods to adapt and the eye to achieve maximum sensitivity.LegalSeeAdaptationAcronymsSeedrug abusedark adaptation
Words related to dark adaptationnoun the process of adjusting the eyes to low levels of illuminationRelated Words |