About Visual System Keynote shapes: diameter of the eyeball about 2.5 cm outside the eye is covered with a dense opaque shell - the sclera. The front part of the sclera becomes transparent cornea - the cornea, which acts as a converging lens and provides 75% of the eyes ability to refract light. On the inner side is covered choroid sclera consisting of blood vessels feeding the eye. In the front part of the eye choroid enters the iris, which is colored differently in different people. In the iris is a round hole - the pupil. Pupil narrows in case of increasing light intensity and expands in case of weakening. Visual System Keynote shapes allows you to specify the parts of the eye.