Must-knows about 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 methods for myopia, hyperopia and astigmatism, contact lenses have gained a 20% share in U.S. Today, contact lenses are available for most people in many more options, even if some people were deprived by technological limitations in the past.
Similar to 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 classifying contact lenses: material, wearing schedule, replacement schedule and lens design.
Possible contact lens materials
Generally, there are three types of materials (Plexiglas, water-containing plastic and waterless plastic) that can be used to manufacture contact lenses, creating their respective products: 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 people with 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.
Daily wear and extended wear contact lenses
From the perspective of wearing period or wearing schedule, there were only daily wear contact lenses before 197. This type of contact lenses must be removed every night. Most contact lens products are approved by FDA under this restriction. Sleeping without contact lenses in the eye is expected to minimize the risk of getting an eye infection. After the invention of extended wear lenses, people are allowed to let the lenses stay in the eyes overnight for up to 30 days. At a shorter interval, there are similarly 7-day extended wear contacts.
Contact lenses with different replacement schedules
Another way to categorize contact lenses is to consider disposal interval, or more exactly replacement schedule. 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.
Available contact lens designs
Different designs have been applied to contact lenses: spherical, bifocal, orthokeratology, toric, as well as many other rare designs. Spherical lenses are round and for both myopia and hyperopia correction. Bifocal lenses have two focal points for different vision problems. Orthokeratology lenses are for cornea reshaping 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. Using special colors, special-effect lenses may provide a special image for the wearer, like a cat, a zombie. Custom lenses solve the problems that are beyond ordinary lenses. UV-protection lenses contain an UV blocker to offer UV protection in the same way as UV sunglasses do, although they can not protect your whole eyes. Hybrid lenses combine the features of soft lenses and rigid lenses.
Contact lens selection
The selection of contact lenses requires some tips. By obeying the 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, customers can choose their favorable colors, wearing periods and so on. With a prescription, you can also buy contact lenses from other ECPs or any possible source as you wish.
Multipurpose solutions are more convenient
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 can be incorporated in a single bottle of multipurpose solution.
A period of trial may be necessary
People who wear contact lenses may suffer from poor vision or discomfort when they firstly try them on, because their eyes may 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 made by your ECP.