![]() ![]() ![]() Because some nerve connections cross over to the other eye, both pupils contract in unison. This is the result of a nerve signal generated in the back of the eye triggering the muscles in the iris. Switch to bright light and the pupils automatically contract. ![]() In dim light the pupils dilate (open wider) so more light can enter. Its main function is to regulate the amount of light that enters the eye. The colored part around the pupil called the iris adjusts the size of the pupil. They appear black because light almost never escapes through them. The pupil is the opening in the middle of the front of the eye that allows light to enter. The brain then makes sense of the signals, giving us the experience of seeing. As a result signals zoom along the optic nerve to the brain. This light triggers light-sensitive cells in the retina at the back of the eye. Have you ever considered taking a nighttime nature walk? Would you wait until there is a full moon so you could benefit from sunlight reflected from the moon-or would you rather take a flashlight? Do you think trees would look black, green or gray in the dark? Try this activity to examine your night vision and prepare for your next nighttime adventure! ![]()
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