What Are Contact Lens Made Of
Soft contact lenses are made of plastic, but not the type of plastic used in garbage bags or paper plates. Instead, soft lenses are made of hydrophilic plastics - a special type of water-absorbing plastic that stays soft and moist as long as it is absorbing lots of water, made of cast moulding technology . As long as that plastic stays nice and wet either inside our eye or in a case, the plastic stays pliable and soft. To our eyes, this soft flexibility spells comfort. When our eyes are dry, our lenses will begin to feel uncomfortable because they depend on moisture to keep them in place and pliable. Soft contact lenses are categorized by the amount of water they contain. They can be classified as either high water or low water. Most extended wear contact lenses are made out of silicone hydrogel - a material that combines the water-absorbing plastic of soft lenses with silicone. Adding silicone to the hydrogel plastic creates cast moulding contact lenses that stays moist a...