Slow motion video shows iris movement

The iris is the pigmented, visible part of vertebrate eyes, with small muscles that keep it safe in its place. The video above, posted on YouTube by Gav and Dan of The Slow Mo Guys, shows the movement of this structure, which appears to be loose and moving even after the eye is still.

In addition, the iris also has an opening in its center, the pupil, which controls the light entering the eye. The clip images were captured with a Phantom Flex camera at a speed of 1, 000 frames per second, recording movements barely visible to the naked eye.

Source: YouTube