Hydrogel contact lenses

Hydrophilic gels are, in principle, polymers that contain a large percentage of water. Each macromolecule is combined in spatial lattice chemical bonds, which guarantee the dimensional stability and insolubility. Amount of hydrophylic monomers allow to create a range of gels with different properties.

Hydrogels have reached in the last forty years, a large application in medicine due to their permeability for low molecular weight substances, the minimum protein interaction and small mechanical irritation of the tissue (due to the softness and consistency of rubber materials).

The exceptional position among the hydrogel contact lenses for medical applications (the same goes for contact lenses) keeps material called HEMA polymer. For its excellent properties in terms of biocompatibility, toxicity, water volume, this kind of hydrogel is considered a standard for comparison with the new polymers in medicine. Likewise, in contactology HEMA lenses are known to be normal. This follows from a relatively long period during which this material is used with good results, the frequency of its use and be able to evaluate longer term effects of its impact on human organism. For many applications, sufficient swelling, favorable holds-strain properties, making it easy to heat sterilization, hydrolytic stability, resistance to enzymatic cleavage are other prerequisites for its popularity.

The hydrophilic gel contact lenses are about as soft as tissue. This reduces mechanical irritation of the tissue and increased tolerance of the gel. Damage to the body is smaller.

Hydrogel contact lenses are permeable for water-soluble low molecular weight substances such as oxygen, carbon dioxide, lactic acid. As a material for contact lenses are so favorable for the metabolism of the cornea than hydrophobic polymers.