How Contact Lenses Work

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You’re walking outside when rain is falling down in icy sheets chilling you to the bone. Water keeps condensing on the glasses lens and fogs your vision. You erase any remains, but it keeps happening. There’s got to be a better solution!
Contact lenses are a thin lens placed on the surface of the eye. They are considered a medical device that can be worn for correcting vision, cosmetics, or therapeutic reasons. It has been estimated that 125 million people use contact lenses worldwide, which is approximately 2% of the world’s population. Contact lenses are shaped based on the vision problem to help the eye focus light directly on the retina. There are four main reasons to wear corrective contacts:
• Hyperopia (you cannot see close up)
Myopia (you cannot see far away)
• Astigmatism (refractive error of the eye)
• Presbyopia (aging eyes)
Hyperopia
If you are farsighted, your eye does not have enough focusing power — light rays fail to form a focus point by the time they reach the retina. Contact lenses rectify hyperopia by converging light rays, which increases the eye's focusing power. This moves the eye's focus point ahead, onto the retina where it belongs. To correct farsightedness the contact lens is thicker in the center and thinner at the edges. These lenses are known as convex.
Myopia
If you have myopia, light beams focus too early within your eye — they form a focus point in front of the retina instead of right on it. Contact lenses correct nearsightedness by separating light rays, which minimizes the eye's focusing capability. This moves the eye's focus point back, onto the retina. Contact lenses designed to correct nearsightedness are thinner in the center and thicker around the outside. These types are cal...

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...ision problems that can easily be corrected with something as simple, yet intricate as a little piece of plastic.

Works Cited

Watson, Stephanie. "Contact Lenses" 09 January 2006. HowStuffWorks.com. 04 March 2014.

"DC Area Eye Care Doctors and Optometrists." How Contact Lenses Work. N.p., 2009. Web. 06 Mar. 2014. .

"Contact Lenses." How Work. N.p., 2010. Web. 09 Mar. 2014. .

"PupilEyes." PupilEyes. N.p., 2010. Web. 09 Mar. 2014. .

"Hyperopia (Farsightedness) and You." Hyperopia (Farsightedness) Causes. Alcon, 2014. Web. 06 Mar. 2014. .

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