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24-08-2013, 14:20

Types of contact lenses: hydrogels and thermoplastic

Proven tips

Contact lenses are a convenient and reliable means for the correction of vision, allowing people with low vision to see the world in all its diversity. These use the most advanced materials that do not cause allergic reactions, and allows you to wear lenses for a long time.
Types of contact lenses: hydrogels and thermoplastic

A clear "picture" of reality
The first contact lenses of plastics were invented in 1938, and in the early 60s of the last century has been designed hydrogel, which became the basis for the modern materials used in the manufacture of lenses. Today, it is thermoplastic and hydrogel materials are most popular for manufacturing lenses.
Contact lenses from hydrogels today make up about 90 percent of the total volume of produced lenses. The hydrogel lens material provides advantages such as the ability to retain and allow moisture, which is an important factor when wearing comfort and smoothness and elasticity.
Smooth lenses have better interaction with the cornea and upper eyelid, do not create a sense of friction. The elasticity of the hydrogel minimizes mechanical stress on the cornea and sclera. In addition, the use of hydrogel lenses minimizes the risk of infection if not properly stored or used. "Alignment" of such lens does not move, his eyes quickly get used to them. A hydrogel contact lens to the cornea receives six times more oxygen than traditional soft lens. These lenses are not only suitable for people suffering from astigmatism, because, having a large coefficient of permeability is not enough, they are not designed to correct this defect of vision.
Contact lenses are made of thermoplastic differ permanently resilient and are hard lenses. They are durable and easy to care for, but their disadvantage is airtight and fragility. Lenses made of thermoplastic is also more susceptible to the formation of protein deposits. In contrast to hydrogel lenses are capable of more correct astigmatism diopter and have a longer service life. Their size , larger in diameter than the lenses of the hydrogel facilitates the procedure of putting on and removal.