The human eye is an incredibly powerful sense organ. Unfortunately, sometimes it needs some help to work up to its potential. Fortunately, help is available in the form of spectacles and contact lenses.
The eye works somewhat like a camera. It has a lens that, when it is working properly, causes the image of whatever is being looked at to be in focus on the retina at the back of the eye. The retina then captures the details of the image and sends them to the brain for processing.
For many people, the focusing doesn’t work right, or only works in some conditions. Several hundred years ago, when people began experimenting with lenses, it was found that positioning a properly made lens in front of the eye could in many cases correct the focusing errors of the eye’s built in lens. This led to the development of eyeglasses, or spectacles, which many people still use today for better vision than what they have without them.
Contact lenses differ from spectacles in that they are positioned directly on the eyes. Leonardo Da Vinci had the basic concept, but the first practical contacts did not appear until the twentieth century. The first widely used ones were made around 1950.
Contact lenses have several key advantages over spectacles. They support a much wider field of vision. They also are less likely to become soiled or steamed up by the weather. Many people feel that their appearance is better without glasses over their eyes.
Early contacts were made of glass and covered much more of the eye than the cornea, the portion that admits light into the eye. The conversion to plastic happened pretty early on, as did the move towards smaller lenses that just cover the cornea. Both of these moves helped make contacts easier to wear.
Early plastic models were hard and could only be worn for a limited amount of time. The use of materials that could allow oxygen to move through the lens to the surface of the eye increased the time they could be worn. The use of softer materials did even more to increase comfort and wear time.
Soft contacts have become much more widely used than hard ones, because of their greater comfort and ease of use. Hard contacts require an acclimation period during which they are worn for longer periods of time each day. Soft ones can be worn for long times from the beginning. Extended wear models can be left in for as long as 30 days. The soft ones are made from materials referred to as hydrogels. They contain a significant amount of water.
Contacts need to be disinfected and cleaned periodically. When not in use, they are normally stored in a container with cleaner or a multipurpose solution. Treatment with disinfectant is important to prevent eye infections from microbes on a lens. Protein can build up on a lens and make it uncomfortable. The use of an enzymatic protein remover is important to prevent this. Not all cleaning and disinfectant solutions are appropriate for all lens materials, so it is important to read the fine print and follow instructions carefully.
Contact lenses are not for everyone. Some people think they look better with glasses on. Others have difficulty placing objects directly onto their eyes. However, many people have found that they are the best way to correct deficiencies in vision.
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