Contact lenses are vision aids (or cosmetic decorations) that consist of a pair of small, convex, transparent discs that are placed directly on the eye, over the cornea. Contact lenses are usually used to correct vision problems, such as shortsightedness or long-sightedness, although purely cosmetic contact lenses that change the color of the eye have come into common use in recent years, too. The materials used to manufacture lenses have become steadily more sophisticated, making the lenses safer, more comfortable, and more effective over time.
The origins of contact lenses
Different kinds of lenses have been used for centuries to correct eye vision. The first eyeglasses were apparently developed by Salvino D’Armante around 1284 in Pisa, Italy, however some like to credit Alessandro Spina from Firenze with this invention.
Leonardo da Vinci drew sketches of what resemble contact lenses as early as 1508.
Another idea for contact lenses seems to have been developed in 1636 by the French philosopher René Descartes. Descartes’ idea to use a water-filled glass tube to correct vision, but since the tubes would force the eyelids to remain open, the concept was never pursued further by him or his contemporaries. The idea languished in obscurity for several centuries after that.
The first practical contact lenses were made by a German glassblower – one F. E. Müller – in 1887, and almost immediately improved by another German, Adolf Fick, who made glass lenses filled with dextrose solution in 1888. These lenses were tested first on rabbits, then on Fick himself, and were large and uncomfortable, capable of being worn for an hour or two at most.
Lighter, more comfortable plastic lenses were introduced in the 1930s, close to fifty years after Muller’s and Fick’s breakthroughs. Corneal lenses, which cover less of the eye than the previous types, were introduced in 1949, laying the groundwork for modern lenses. Corneal lenses can be worn for up to sixteen hours at a time, allowing people to benefit from these lenses during their entire waking day – contrasting with the brief periods that the previous scleral lenses could be worn.
Modern contact lenses
There are various reasons why people wear modern contact lenses. One common reason is that they need vision correction, but prefer not to wear eyeglasses. Eyeglasses change a person’s appearance, and can be inconvenient at times, since they press on the bridge of the nose while worn, and need to be carried when not in use, raising the risk of being dropped.
Furthermore, the lenses of eyeglasses quickly become dirty and smeared, and also have an annoying habit of getting steamed up. Carrying a possible spare set of eyeglasses and a case for the original pair can also pose an inconvenience.
Contact lenses free the individual from the necessity of wearing glasses and carrying glasses along with them wherever they go. Certain unusual types of vision problems are better corrected with contact lenses than with regular eyeglasses, too.
Today’s advanced technology has greatly improved contact lenses over the hard, uncomfortable glass lenses that first appeared in the 19th century. In the 21st century, second-generation silicone hydrogels are currently used for many popular brands of contact lenses.
These hydrogels keep the surface of the eye moist and comfortable, yet allow plenty of oxygen to flow through, keeping the eye healthy. Third-generation hydrogels were patented very recently, with even greater oxygen permeability and up to 46% water in their structure. These hydrogels should be even more comfortable and even safer to wear than the current contact lenses.