To keep the eyes safe and comfortable, contact lenses are made of many different materials.
The major material used in the manufacturing of the contact lens, is a high-grade plastic polymer. Through research into new materials including the new types of polymer the three types of contact lenses were developed over the course of time. They are the hard, soft and gas-permeable contact lens.
The polymer for the hard lenses (originally made from glass) is called polymethylmethacrylate (PMMA). These lenses are not as comfortable on the eyes due to their rigid surface and lack of flexibility.. The soft lenses are made from polyacrylamide, (HEMA). HEMA is similar to the acrylic fibers used to produce clothing fabrics. These are reported to be much more comfortable. The gas-permeable lenses are made from HEMA, silicones and fluoropolymers. It only takes a couple of hours for the wearer to get used to this type of lens. Since the beginning of the mass popularity of contact lenses, there have been some changes.
One change is that PMMA is no longer in use, and has been replaced with rigid plastics. HEMA is replaced by polymers that contain 80% water, which has helped to reduce corneal problems in many contact lens wearers. These new materials are also permit increased efficiency in manufacturing of disposable contact lenses. All of the materials used in the lenses are flexible and gas permeable.
Contact lens materials are divided into two groups often according to the type of lens, the hydrophilic and the hydrophobic. The materials that contain more than 10% water by weight referred to as hydrophilic. The hydrophobic are the lenses with less than 10% water by weight. A few example of hydrophilic materials are abafilcon A, alphabilcon A, etafilcon A, and almost 80 more materials. Some of the hydrophobic materials are amefocon A, cabufocon A, dimefocon A and again about 80 more in this category.
One of the most recent advancement in the spectrum of materials used to construct contact lenses has been the advent of silicon hydrogels. Silicon hydrogels contain a far higher percentage of water than more traditional materials (often in excess of 80%) and allow for a great increase in the amount of oxygen transmitted to the cornea.
With constant research going on to manufacture contact lenses that can do more, help the eyes more, and even be safer to the wearer, this list of materials could easily change again.
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Buying contact lenses online is for many a more affordable solution than the average high street optician. Lower costs allow online suppliers of contact lenses to offer lower prices than many high street retailers. Visit http://www.lensfinder.co.uk to compare the price of contact lenses from major online UK retailers and find the cheapest price for your contact lenses in the UK.
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