How Do Our Eyes Work?

Understanding your range of vision

Our eyes work much like a camera. In a camera, light passes through the lens and focuses on the film. Each of your eyes also has a crystalline lens

Crystalline lens: Structure inside the eye that help to bring rays of light to a focus on the retina.

, which is located just behind the iris

Iris: The colored part of the eye surrounding the pupil which controls the amount of light that enters the eye.

. As an image passes through the cornea

Cornea: Clear front surface of the eye that covers the iris and pupil. The cornea provides most of an eye's optical power.

, your lens focuses those lights, colours and shapes on the retina

Retina: The transmitter located at the back of your eye that sends the images to your brain.

, a "transmitter" located at the back of your eye. The retina then registers these images and sends them to your brain. Sometimes the shape of your eye doesn't bend the light properly, and can lead to common vision problems like short sightedness and long sightedness.

By contracting and relaxing the muscles that make up the ciliary body

Ciliary body: An eye muscle that controls the shape of the lens to enable the eye to quickly change focus to see objects at near, intermediate and far distances.

, you are able to focus your vision on things close up, far away and everywhere in-between. This function, called accommodation

Accommodation: The ability of the eye's lens to change shape to focus on objects at various distances.

, allows us to see objects throughout our range of vision.

As we grow older, the muscles that control our eyes become weaker and we lose the ability to accommodate. This leads to a condition called presbyopia

Presbyopia: An eye condition commonly due to aging and a stiffening of the lens, which results in an eye that can no longer accommodate for near or "reading" vision. The individual is no longer able to read clearly and typically requires reading glasses.

, which is one of several age-related vision problems.