Like most human traits, blue eyes are determined by genes ... which is when the lens of your eye (right behind the iris) ...

In this video, learn about different parts of the human eye and ... circle is called the iris and the black spot in the middle is the pupil. This is the part of the eye that lets the light in.

The intricacy and seeming perfection of the eye, both as an object of anatomical beauty and as a working machine, have worried and intrigued scientists, philosophers and zealots, especially during ...