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About this Article
Written by: Mueller
Written on: March 1st, 2000
Tags: biomedical engineering, health & medicine
Thumbnail by: Print by the Detroit Publishing Company, after painting by Charles Willson Peale./Wikimedia Commons
About the Author
At the time this article was written, Mueller was a student at the USC Viterbi School of Engineering.
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Volume II Issue II > Designing Vision
With the rapid technological advancements, it is easy to forget the significant inventions of years past. However, since the 1700's, only a few modifications have altered the basic design of today's eyewear. The development of contact lenses eliminated the awkward frames of glasses, but at the expense of frequent replacement and eye irritation. Now laser surgery may eliminate the need for contacts. Despite the continuous evolution of vision correction, one thing remains certain: the same optical principles will continue to govern developing products, no matter what form they take!

Introduction

The role of eyewear cannot be underestimated in today's society. Millions of people use glasses each day to overcome eye deficiencies and improve the quality of their vision. While some despise their appearance, many find glasses an essential aid for day-to-day life. For those concerned with their image, contacts provide an aesthetic alternative that offers improved vision without the frames. Still others enjoy the fashion of sunglasses, with their stylish design also functioning to block the sun's rays. Although many innovations are taken for granted, behind every set of frames and lenses lies a feat of engineering design. This article investigates the properties that make glasses, contact lenses, and sunglasses overcome common vision problems.

A Brief Background on the Eye

The eye is the critical link that translates light from the environment into the visions our brain perceives. By expanding and contracting in response to environmental conditions, the pupil regulates the amount of light to enter the eye. In dark environments, the pupil expands to allow the maximum amount of light to enter the cornea. In bright areas, the pupil contracts to limit the amount of light to enter. Light enters through the glasses, contact lenses, and sunglasses overcome common vision problems.
Light enters through the eye's covering, the cornea, and passes through the lens. Muscles in the eye can change the structure of the lens, making it more or less spherical in accordance with the environment. The light ray changes angle in response to the muscular contraction, and the light bends onto the retina. Located at the back surface of the eye, the retina is the site where the nervous system translates the light signal into a form that can be interpreted by the brain. Vision problems arise when either the lens is unable to bend light onto the retina, or the retina is unable to translate the light into a signal that can be interpreted by the brain. Heredity, eyestrain or a variety of other problems or injuries may cause the retina to lose its ability to properly handle light.