Contact lenses can be categorized as soft conventional hydrogel, silicone hydrogel, or rigid gas permeable contact lenses. According to Contact Lens Spectrum, all contact lenses utilize a polymer backbone. A polymer is a chemical chain formed from linking many smaller molecules.
Soft Conventional Hydrogelo Soft conventional hydrogel contact lenses share a common backbone of the polymer polyHEMA. This polymer serves as the base for all soft contact lenses, and
different brands are formed by injecting differing amounts of water and other chemicals into the contact lens as it is manufactured.
Silicone Hydrogelo Silicone hydrogel contact lenses are also known as breathable contact lenses. These
contact lenses can be worn overnight in some cases. Silicone rubber is used as the polymer backbone in silicone hydrogel contact lenses. Other chemicals, such as polydimethylsiloxane, are also added to improve comfort.
Rigid Gas Permeable
o Rigid gas permeable contact lenses are also known as hard contact lenses. Rigid gas permeable contact lenses contain differing amounts of methyl methacrylate, fluorine, silicon and other chemicals to make them comfortable to wear.
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