Human eye

Photomacrograph of a human eye. The human eye is a complex organ and works in a similar way to a camera. Light enters the eye through the pupil (black). The size of the pupil is controlled by the iris (hazel) in order to adjust how much light enters the eye at any given time. Here, the iris is coloured hazel, but other colours such as brown, green, blue and grey can be present instead. Light enters the eye and is focused onto the retina at the back of the eye, which then converts these images into electrical signals and sends them on to the brain to interpret and make sense of. The sclera (white part of the eye) and eyelashes are also visible here. Width of image is 5 cm.