dark adaptation

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dark adaptation

The 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.
References in periodicals archive ?
Individual preparations were dark-adapted until the response to a dim test flash remained constant for 1 h.
Experiments were conducted on seven dark-adapted specimens at 3 [degrees]C, five of which were again tested under light-adaptation (478 nm) at 3 [degrees]C.
To measure the spectral efficiency of luminescent countershading, dark-adapted animals were first exposed to a 490-nm stimulus (at 2.24 X [10.sup.13] photons [m.sup.-2] [s.sup.-1]) for 25 min to induce counterillumination.
Figure 1A shows the intensity response functions for a single dark-adapted ommatidium during the day and at night.
In this study, all factors, with the exception of the stimulus intensity, were equal for all the species: they were all completely dark-adapted before being presented with a flickering light stimulus, the background intensity was 0, and the eye was always bathed with a circle of light that was larger than the eye itself.
MSP recordings were further performed on photoreceptors of a dark-adapted, 4-month-old cuttlefish.
GOOD OBSERVING PROJECTS usually take planning and preparation, not to mention optical aid and dark-adapted eyes.
Following techniques described elsewhere (5), we mounted a crab on a rigid platform in an aquarium contained in a lightproof, shielded cage and, using corneal electrodes, recorded electroretinograms (ERGs) from their dark-adapted lateral eyes in response to 20-ms light flashes generated by a green LED.
All white lights are banned after sundown, giving observers the chance to become fully dark-adapted during the event.
The flash duration at which the maximum ERG amplitude was reached and maintained for three consecutive measurements was taken as the length of the flash response for a dark-adapted eye.
Finally, ensure that you're fully dark-adapted before you peer into the eyepiece.
Pieces of retina extracted from dark-adapted animals were teased apart in Ringer solution, placed between two coverslips, sealed, and individual photoreceptors examined with the dichroic microspectrophotometer (2).