Hydrogel is an artificially created hydrophilic (water-binding) material. The development of hydrogel dates back to the 1930s and the first attempts to create a material of a gel structure. The first hydrogel material was developed by Czech scientists Otto Wichterle and Drahoslav Lime in the 1950s and was called HEMA. The hydrogel is a network of polymers connected by various types of chemical bonds. This material contains a large amount of water, thus is highly biocompatible and able to transmit oxygen. Hydrogel itself is not a breathable material, thus oxygen is not able to penetrate through it. The oxygen molecules are transported through the hydrogel with water contained therein through the process of diffusion.
Due to their high proportion of water, Hydrogel contact lenses are not only comfortable, but also provide sufficient supply of oxygen to the cornea.