These hard lenses are also known as RGPs (ridgid gas permeable). They are newer progression rigid or hard lenses made of plastics combined with other materials, such as silicone and fluoropolymers, which allow oxygen in the air to pass directly through the lens. For this reason, they are called gas permeable. Once fitted, they are replaced every year.
RGPs are sometimes the first lens of choice for particularly complex prescriptions which may not be available in soft lenses. The range of soft lenses in recent years has seen a decline in RGP lenses and now only a few optometrists have extensive experience of fitting these lenses.
At National Vision Optometrists, we have many years of experience in fitting such lenses and often receive referrals for more complex cases such as keratoconus (irregularly shaped corneas).