Contact lenses are medical devices that, when placed on the eye can correct shortsightedness, farsightedness and astigmatism. They can also be worn for cosmetic or therapeutic reasons.
People choose to wear contact lenses for many reasons. Aesthetics and cosmetics are often motivating factors for people who would like to avoid wearing glasses or would like to change the appearance of their eyes. Other people wear contacts for more visual reasons. When compared with spectacles, contact lenses typically provide better peripheral vision, and do not collect moisture such as rain, snow, condensation, or sweat. This makes them ideal for sports and other outdoor activities.
Additionally, there are conditions such as keratoconus and aniseikonia that are better corrected with contact lenses than glasses.
Although contact lenses have been available for over a century, the development of PMMA (polymethyl methacrylate) or Perspex promoted the development of plastic corneal hard contact lenses. In 1971 the first soft contact lens was approved by the American Food and Drug Administration. Since then the advancements in both material and design have made contact lenses first choice for over 15% of the world’s population.
The prescribing of contact lenses is restricted to eye-care practitioners (Optometrists and Ophthalmologists). The best type of lens will be prescribed based on your visual requirements, eye structure and tear quality. Although your contact lens prescription is usually similar to your spectacle prescription the two are not interchangeable.
The many types of contact lenses currently available can be grouped in various ways according to:
Design of the lens