Difference between soft and hard contact lenses
SSoft lenses are manufactured from a plastic hydrogel polymer, HydroxyEthylMethacrylate (HEMA) which has a varying water content (38% - ~70%). Lens size is between 13.00 and 14.50mm. Centre thickness from ~30um.
Hard contact lenses are manufactured from a rigid material, PolyMethylMethacrylate (PMMA). This material can be combined with other plastics to increase the oxygen permeability. Lens size is between 8.0mm and 10.00mm. Centre thickness from ~100um.