The first choice when considering contect lenses is whichlens material will best satisfy your needs. There are five typse of contect lenses, based on type of lenses material they made of with Best Metirials.
Soft lenses are made from gel-like,water-containing plastics called hydrogel.these lenses are very thin and pliable and conform to the front surface of the eye. Introduced in the early 1970s, hydrogel lenses made contect lens wear much more populer becouse they typically are immediatly comfortable. The only alternative at the time was hard contect lense made of PMMA plastic. PMMA lenses typically took weeks to adaptto and many peaple couldn't wear them successfully.
Silicone hydrogel lenses are an advanced type of soft contect lenses that are more porous than reguler hydrogel lenses and allow even more oxygen to reach the cornea. Introdued in 2002, silicone hydrogel contect lenses are now the most populer prescribed in the all over the world.
Gas permeable lenses - also called GP or RGP lenses- are rigid contect lenses that look and feel like PMMA lenses but are porous and allow oxygen to pass through them. Becouse they are permeable to oxygen, GP lenses can be fit closer to the eye than PMMA lenses, making them more comfortable than conventional hard lenses. Since their introduction in 1978,gas permeable contect lenses have essentially replaced nonporous PMMA contect lenses. A significant advantage GP contect lenses is sharoer optics due to the rigid nature of the lens material.
Hybrid contect lenses are designed to provide wearing comfort that rivals soft or silicone hydrogel lenses, combined with the crystal clear optics of gas permeable lenses, Hybrid lenses have a rigid gas permeable central zone, surrounded by a "skirt" of hydrogel or silicone hydrogel material. Despite these features, only a small percentage of peaple in the U.S. wear hybrid contect lenses, perhaps becouse these lenses are more difficult to fit and more expensive to replace than soft and silicone hydrogel lenses.
PMMA lenses are made from a transparent rigid plastic material called polymethyl methacrylate (PMMA) , which also is used as a substitute for glass in shatterproof windows and is sold under the trademarks Lucite, Perspex and Plexilas. PMMA lenses have excellent optics, but they do not transmit oxygen tothe eye and can be difficult to adapt to. These "hard contacts"have virtually been replaced by GP lenses and are rarely prescribed today.