What we see is made in the brain from signals given to it by the eyes.
What we see is in fact made in the brain. The brain makes sight from signals given to it by the eyes.

What is the normal structure of the eye?
The eye is made of three parts.

• A light focussing bit at the front (cornea and lens).
• A light sensitive film at the back of the eye (retina).
• A large collection of communication wires to the brain (optic nerve).

A curved window called the cornea first focuses the light. The light then passes through a hole called the pupil. A circle of muscle called the iris surrounds the pupil. The iris is the coloured part of the eye. The light is then focused onto the back of the eye by a lens. Tiny light sensitive patches (photoreceptors) cover the back of the eye. These photoreceptors collect information about the visual world. The covering of photoreceptors at the back of the eye forms a thin film known as the retina. Each photoreceptor sends its signals down very fine wires to the brain. The wires joining each eye to the brain are called the optic nerves. The information then travels to many different special ‘vision’ parts of the brain. All the parts of the brain and eye need to be present and working for us to see normally.

The Cornea

provides most of the focusing power when light enters the eye. It comprises five layers of tissue. The outer layer, the epithelium, serves as a protecting function. Consisting of highly regenerative cells, it facilitates the fast healing of superficial injuries.

The Pupil

This is the “black circle” within the eye. Its primary function is to control the amount of light entering the eye. In a bright environment the pupil would become smaller to allow less light through, while darkness would make it expand, allowing more light to reach the back of the eye.

The Iris

This is the coloured part of the eye, and its primary function is to control the size of the pupil through contraction or dilation of the iris muscles.

The Lens

This is the clear structure behind the iris and by altering its shape it is responsible for fine-tuning the eye for focusing and reading.

The Retina

This consists of a network of nerves lining the inside wall of the eyes. Acting like a camera, it transmits images to the brain.

The Optic Nerve

This carries images from the retina to the brain.

The Sclera

This is the white part of the eye, providing structure, strength and protection to the eye.

The Vitreous

This is the clear, “gel-like” substance located inside the eye cavity, creating the spherical shape of the eye.