The Human Eye

The Anatomy                                      The Function                                             Safety

This website is all about the anatomy, function and safety of the eye.  It will be discussing the parts of the eye and the problems that can occurr.  There are ways to prevent these problems if you take certain precautions, and they will also be discussed on this page.  Links to other pages will be provided if you wish to learn more about the eye.

The Anatomy     The human eye consists of many parts as you can see by the picture to the right.  Each part of the eye has an important job. Some other main parts of the eye are the cornea, pupil, lense, the iris, and the retina.  All of these parts and many more are all important to the function of the eye.

This diagram shows some of the parts of the eye

The Function- How do we See?     The retina is a very important part of the eye.  This thin layor of tissue at the back of the eye contains the light-sensitive receptor cells that differentiates between the different primary colours.  These cells are sensitive to specific colours  like red green or blue.  The combinations of these colours give the variations we see. The light and shadows that bounce of an object are projected

The laense and the cornea are the optical systems whose job it is to focus an image of an object in the retina.  The cornea has the more important role because light rays are bent when they pass over the cornea.  The image on the retina is upside down compared to the original light source.  It also flips right to left.     The amount of light going into the eye is controlled by a muscle that is a ring like pigment called the Iris.  The hole in the centre is called the pupil.  The Iris muscle contracts in bright light, so the pupil becomes smaller and in low light situations the Iris relaxes and lets the pupil get larger.  Both of these actions are a reflex.

These are the cone cells that are located in the retina

The lens also plays a key part in how we see.  Have you ever wondered why you need to wear glasses and your friend doesn't?  Well, it is because of the lens in your eye.  The shape of your lens determines whether you are near or far sited.  The lens in the eye also directs the light on the retina which sends signals to your brain.  Cells are added to the lens throughout life but as we grow older the central cells age and die off. The lens becomes stiff also affecting near and far vision.

This is a picture tht will help you understand the diseases

If any of these symptoms are occuring with your eyes you should see your doctor: -blurry vision -problems with change in light -Colours appear faded or dimer -decreased night vision -double or multiple vision -you need new perscriptions for your eyes frequently

Safety    There are certain precautions you must take when dealing with your eyes.  Here are some things you should do: -wear sunglasses to protect your eyes from UV rays -When working with chemicals always wear goggles or safety glasses -When working with chemicals, if you get something in your eye flush it out quickly then see a doctor -Wear the proper perscription for glasses

How Stuff Works

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References Web                                            Yahoo                                                     All About Vision How stuff works National Eye Institute Books Vander, Arther, Sherman, Jane and Luciano, Dorothy. Human Physiology: The Mechanisms of             Body Function. Toronto: McGraw-Hill, Inc., 1970. Thompson, J.S. Core Textbook of Anatomy. Toronto: J.B. Lippincott Company, 1977