Contact lenses are composed of many chemicals like those found in chemistry labs. 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 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.
