How has the Invention of Contact Lenses affected people's Sight?

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Manon Mollard MP5a                                                                                      14.12.04

Biology: The Impact of Man’s Inventiveness on the Human Body.

How has the Invention of Contact Lenses affected people’s Sight?

Introduction

        People with sight troubles have had the possibility of wearing glasses for a really long time, but the new technology made available contact lenses. In this essay, I am going to look at the different contact lenses types that exist, at who invented them and when, for which vision problems they are solution, at how to take care of them, at how common they are in our society and finally, I will write about my own opinion.

What contact lenses are

According to the Macmillan Dictionary (2002), contact lens may be defined as “a plastic lens that you wear in your eye to help you see more clearly”.

A very wide variety of contact lenses are available in today’s society, including hard and soft (even if soft is by far more common now), disposable and extended wear; this makes it easy for each person to chose the appropriate type of contact lens for her. The main types of contact lenses are listed below:

  • Soft lenses: As these lenses are soft, they are made of a large percentage of water, and this allows oxygen to pass through the lens and reach the cornea. They are also more comfortable and easier to adapt to.
  • Rigid-gas permeable lenses: these lenses are not made of water so they are not as comfortable as the soft ones, but they do allow a larger amount of oxygen to pass through them. Their best advantage is that they offer a excellent sight correction.
  • Disposable lenses: Disposable means that the lenses are worn for a definite period (from two weeks to six months depending on the lenses) of time before being thrown away and replaces by a fresh new pair. The fact of throwing out the lenses helps making sure the lenses are always very clean, so healthier and more comfortable.
  • Extended wear lenses: these lenses are made to be worn 24h a day, and up to seven days on a row (a new type made of ‘silicone hydrogel’ allows more oxygen to flow in so that they can be kept for up to 30 days without taking them off).
  • Bifocal contact lenses: this type of lens has two major functions: to correct distance vision and to correct near vision. There are two main designs: the power or seeing far is concentrated at the top and the one of seeing nearby at the bottom, or the different powers are blended on different parts of the lens.
  • Coloured contact lenses: they can be used to correct existent sight troubles, but also just to look prettier, as they come in a large variety of colours, from hazel to blue, passing by grey, purple and green.
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However the lenses type that is mostly used today is a combination of both soft and disposable lenses, simply called the disposable soft contact lenses, because they are the healthiest ones, more comfortable, and major prices differences from an average model of these different types of lenses do not exist.

When and by who they were invented

The famous Italian inventor Leonardo da Vinci was the first one to come up with contact lenses sketches and explanations, at the beginning of the 16th century. It is only in 1801 that Thomas Young developed the idea Rene Descartes had had ...

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