Must-knows about contact lenses

Wednesday, November 18th, 2009 at 3:21 pm Post in Contact Lenses

Contact lenses provide fashion expression and a complete vision field suitable for sports without apparent eyeglasses, and eliminate the need for irreversible refractive surgery. Among vision correction ways for myopia, hyperopia and astigmatism, contact lenses have gained a 20% share in US. Today, contact lenses are available for everybody with many more options, even if some people were deprived by technology limitations.

Similar with pharmaceuticals, the purchase of contact lenses requires an exact prescription from eye care professionals (ECP). The prescription is based accurately on your visual condition, eye structure and tears components. There are four ways of contact lenses classification: materials, wearing period, replacement period as well as lens design.

Generally, there are three types of materials (Plexiglas, water-containing plastic and waterless plastic) used to manufacture contact lenses, creating their respective lenses: hard lenses, soft lenses and GP lenses. Rarely used now, the first material is fading out, while soft lenses remain popular since its creation in 1971. The third material is also known as RGP (rigid oxygen permeable), which flatters most for presbyopia and heavy astigmatism. GP lenses are smaller than soft lenses. During its long history, most soft lenses are silicone hydrogel contact lenses, which reduce the possibility of dehydration.

From wearing period aspect, there were daily wear only contact lenses before 1979, which mean you must remove them every night. After the invention of extended wear, people can wear them without removal at night up to 30 days.

Another way to categorize contact lenses is disposal interval. In general, the more frequently contact lenses are replaced, the less likely to suffer from eye infections resulting from deposits on the lenses. For soft lenses, there are daily disposable, weekly disposable, two-weekly disposable, monthly disposable and even longer period. However, GP lenses are more resistant to deposits and usually last one year or longer.

Different designs are applied to contact lenses: spherical, bifocal, orthokeratology and toric, as well as many other rare designs. Spherical lenses are round and for both myopia and hyperopia. Bifocal lenses have two focal points for different vision problems. Orthokeratology lenses are for cornea reshape during sleep. Toric lenses are created especially for astigmatism.

There are many more contact lenses types. Colored contact lenses may enhance your natural eye color or provide a complete color change. Prosthetic lenses are one of the colored lenses used to mask ugliness of the eyes after accidents or diseases. They are always opaque and offer a normal eye appearance. Special-effect lenses may provide special image for the wearer like a cat, a zombie using special coloration. Custom lenses solve the problems that beyond ordinary lenses. UV-protection lenses contain an UV blocker to offer UV protection in the way UV sunglasses do, although they can not protect your whole eye. Hybrid lenses combine the features of soft lenses and rigid lenses.

The selection of contact lenses requires some tips. By obeying criteria of eyesight and physiology, two things must be assured: proper vision correction and good fitness. ECPs may prescribe special lenses for people with dry eyes. Of course, customer can choose their favorable color, wearing period and so on. With a prescription, you can also buy contact lenses from other ECPs as you wish.

In those early days, the cleaning and storing of non-daily disposable contact lenses required several bottles of cleaning products, which were complex and inconvenient. Currently, all these jobs are incorporated using only one product.

People wear contact lenses may suffer from poor vision or discomfort when they firstly trying them on, because they react differently to materials and cleaning products. After a period of trial, the exact prescription of your contact lenses can be eventually determined, especially for bifocals and toric lenses. During this process, there may be adjustment and change by your ECPs.