The Eye

The eye measures approximately 2.5 cms in diameter and is situated in a well protected eye socket. Further protections is provided by the fatty tissue surrounding the eye. Eye movement is regulated by six muscles, attached to the outside of the eye. The eye functions like a camera. Light enters through the cornea, then passes through the pupil and lens and focuses on the retina. The retina acts like a camera film, reacting to incoming light and sending signals to the brain via the optic nerve. Good vision depends on all the complex components of the eye working well together. The eye consists of these major parts: the sclera, cornea, iris, lens, vitreous, retina, macula and the optic nerve.


The white part of the eye is called the sclera. It is the tough, outermost layer of the eye and assists in maintaining the shape of the eye.


The front part of the sclera is transparent, and is called the cornea and forms a clear dome-shaped window covering the front of the eye. Most of the focusing power when light enters the eye is provided by the cornea, which is composed of several layers of tissue. The outer layer is the eye’s protective layer, which is made up of highly regenerative cells that have the ability to grow back within a few days if injured. It is this part of the eye that laser vision correction surgery is performed on.


The iris is the coloured part of the eye and is an adjustable diaphragm around an opening called the pupil. The pupil is the central black circle that you see in the eye and it appears black because no light is reflected from the eye. The iris muscles effects the size of the pupil, allowing more or less light into the eye.


Behind the iris is the lens of the eye. The lens is a clear, bi-convex structure. Muscles changes the shape of the lens, which focuses light on the retina.


Most of the eye cavity is filled with the vitreous, which is a clear gel-like substance that helps to maintain the shape of the eye.


The retina is made up of light-sensitive cells that absorb light rays and change them into electrical signals.

Macula & Optic Nerve

The macula is a specialised area of the retina, where the light sensitive cells are highly concentrated and is used for fine, intricate visual tasks. The retina processes the light rays into electrical signals which are carried by the optic nerve to the brain. The brain then translates these signals into visual images.