Changes in the eye to adapt to an unusually bright or dim light or to adapt to light after being in darkness.
Reflex changes in the eye to allow vision in increased light (e.g., in normal light after being in the dark or in very bright light after being in normal light); it involves a contraction of the pupil so that less light enters.
Reflex changes in the eye to enable vision either in normal light after being in darkness or in very bright light after being in normal light. The pupil contracts and the pigment in the rods is bleached.
Changes that occur in a dark-adapted eye in order for vision to occur in moderate or bright light. Principal changes are contraction of the pupil and breakdown of rhodopsin. Bright sunlight is 30,000 times the intensity of bright moonlight, but the eye adapts so that visual function is possible under both conditions.