At present, the materials of contact lenses are roughly divided into three types, HEMA, HEMA+NVP and HEMA+Si
HEMA+NVP is based on HEMA by adding NVP components to make the lens very light, thin and soft and not suitable for protein precipitation. The toughness is worse than that of hydrogels.
HEMA+Si is the addition of silicon to HEMA, which makes the lens more moisturizing. It is characterized by good moisture retention and high oxygen permeability (4-7 times that of ordinary lenses). It is suitable for people who are prone to dry eyes.
HEMA lenses are made of hydrogel, and their oxygen permeability is 5 times higher than that of ordinary contact lenses. It is characterized by being strong and durable, but it is prone to protein precipitation, so many daily-disposable beauty lenses are made of this material. Hema material is currently recognized as the most suitable material for color contact lenses. Due to its high water content, it is indeed higher than other materials in terms of comfort. It is suitable for people with healthy eyes, but if your eyes are more sensitive, It is easy to produce red blood and other phenomena. It is best to choose non-ionic materials. The lenses of this material are lighter and softer, and are not prone to protein precipitation.