Contact lenses are thin lenses, now made of plastic, which float above the cornea on the tear layer of the eye. Fashion accessories and instruments of high-tech glasses are increasingly competing with cheap contact lens more discreetly. Evolution with respect to the technologies and materials used in the optical industry has given rise to a considerable increase in the options available for users of contact lenses. The glasses allow light rays to focus again on the retina, rather than ahead of it as a myopia or backward as in hyperopia. Corrective contacts are specially shaped to improve vision by compensating for sight-related problems such as nearsightedness, farsightedness and astigmatism. In addition to their aesthetic interest, contact lens offer the advantage of providing a better field of vision as traditional glasses because of the lack of frame and because they follow the movements of the eye. These days consumers not only have a wide selection of brands to choose from, they also have many different categories of lens types available to them. Contact lenses are mainly used in the correction of myopia (80%) and to a lesser extent, farsightedness, astigmatism and presbyopia. Contact lenses are also more practical to wear at sports or outdoor activities.