There are several types of contact lenses. Soft lenses and rigid lenses are the two types of lenses the most common.
Soft lenses
Soft lenses are the most common, as very adaptable, affordable, and easy to use for most people. Indeed, there are soft contact lenses daily, weekly, biweekly, monthly and yearly. Also, most cosmetic and therapeutic contact lenses are soft lenses.
Hard lenses
There are two kinds of rigid lenses (which replaced the old hard lenses): the first hard lenses are longstanding PMMA (or Perspex / Plexiglas) and modern hard lenses is referred to as RGP (Rigid Gas Permeable ).
Rigid lenses are a modern type of lens that meets the particular carrier likely to suffer from dry eye, due to their high oxygen permeability. They are less common than soft lenses.
Most of the hard lenses are more expensive than soft lenses, but the frequency of replacement is generally less regular. Indeed, some hard lenses can be used for one to two years.
There are significant differences in the requirements of rigid lenses in different countries: they represent 20% of prescriptions in Japan, the Netherlands and Germany but only 5% of prescriptions in Scandinavia.