What is the difference between soft and hard Contact Lenses?
“Hard” lenses;
These lenses were the original contact lenses made several decades ago from a plastic called PMMA. For a long time they were the only kind of lens but they are seldom used anymore as they have several drawbacks and have been superseded by “rigid” lenses. Rigid, or gas permeable, lenses are similar to hard lenses in design and appearance, however as the name suggests, the material they are made of is permeable to gases.
“Soft” lenses;
Soft lenses are slightly larger and more flexible than rigid or hard lenses. Soft lenses are made of materials which soak up water, and it is this uptake of water that allows oxygen to transfer to the cornea. Soft lens material itself is impermeable, so the oxygen is transmitted via the water.