For us to see objects, light reflects off them and enters our eyes.
Let’s look at the structure of the eye in more detail:
The diagram below details the structure of the eye.
Ciliary body – Contains the ciliary muscle, which relaxes and contracts to allow the lens to change shape for focusing.
Iris – The coloured part of the eye, which contains muscles that control the size of the pupil. The purpose of the iris is to regulate the amount of light that enters the eye.
For example, if you’re in a dim environment, your iris will enlarge the pupil to take in as much light as possible. However, if you’re in a bright environment, the iris will constrict the pupil to prevent too much light from entering the eye, which could be damaging.
Pupil – The pupil is the hole located at the centre of the iris. Its function is to let in light and focus it on the retina.
Cornea – The cornea is the eye’s outer lens. It is transparent, so it transmits light and its purpose is to control and focus the entry of light into the eye.
Lens – The purpose of the lens is to focus light on the retina.
The lens can adjust its thickness to focus light correctly on the retina. If this process is faulty, glasses can correct it.
Suspensory ligament – Helps to control the shape of the lens.
Sclera – This is the tough outer wall of the eyeball, serving to protect the eye.
Retina – This is a thin layer of tissue at the back of the eye containing cells that are sensitive to light. This is where the image is formed and the retina sends this information to the brain through the optic nerve.
Optic nerve – Carries impulses from the retina to the brain.
Light hits the lens, which then focuses the light onto the retina
1. When light hits the lens, it is refracted, which means it is bent slightly as it reaches the lens.
2. The refracted light rays focus onto the retina. In the diagram above, you’ll see the retina serving as the focal point, which is the point where converging light rays meet.
3. This information is then relayed to the brain via the optic nerve.