LIGHT AND DARK ADAPTATION
Light Adaptation. When experiencing sudden high levels of illumination the eye quickly adjusts - approximately 10 seconds. However, if a person has been in bright light for a long time, large proportions of the photochemicals in both the cones and rods are reduced thereby reducing the sensitivity of the eye to light. Thus going quickly from outside on a sunny day into a darkened room has the effect of vision being severely reduced until dark adaptation takes place.
Dark Adaptation. On the other hand, if a person remains in darkness for a long time the reverse takes place and both the cones and rods gradually become super-sensitive to light so that even the minutest amount of light causes excitement of the receptors. It takes about 7 minutes for the cones and 30 minutes for the rods for our eyes to adapt to darkness.
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