His gaze softens as he draws closer to you. With one hand around your waist and the other cradling your jaw, he pulls you in. You look into his eyes, and notice his pupils have grown large and hungry.

You look in the mirror and notice that the dark circles in the middle of your eyes are bigger than usual. What's going on? Those dark circles are your pupils, the openings that let light enter your ...

The colored part of the eye surrounding the pupil is called the iris. It automatically regulates the amount of light entering the eyes by regulating the size of the pupil. Light is the primary ...