Our two eyes collect light and convert it into nerve signals that are interpreted in the brain.
Some people call our eyes 'the mirror of the soul'.
Each eye consists of a clear window at the front and a lens to focus light onto the sensory cells in the retina at the back of the eye. A ring of muscle, called the iris, in front of the lens controls the amount of light that passes into the eye. This is very important because the cells in the retina are extremely delicate and can never be replaced if they get damaged by the strong rays of the Sun. This muscle adjusts the shape of the lens so that the eye can focus on objects that are both near and far. All of the nerves from the retina meet at a point called the optic disk.