The next-generation of hard lenses were known as gas permeable lenses. And the lenses were not actually called "hard" anymore, they changed the name to "rigid" to refect the flexibility of the new lense's material.
Really the only problem with these lenses is that while they can absorb a bit of moisture, it's still generally not enough. Hence gas permeables tend to dry out and become uncomfortable by the end of the day. They are a good choice if you aren't happy with the vision clarity provided by soft contacts, and/or are worried about possible infection more frequently associated with soft lenses.
Although they resembled the old style hard lenses, they were light years ahead in the comfort department. Gas permeables allowed the cornea to "breathe" by letting in oxygen and allowing carbon dioxide to escape. They could also absorb small amounts of fluid, and weren't as vulnerable to bacteria as soft lenses. The secret of the new lenses was the addition of silicone to the len's surface area.
Rigid Gas Permeable Contacts Allow Your Eyes To "Breathe", But Tend To Dry Out Quicker Than Soft Contacts.
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Contact Lenses: Rigid Gas Permeable Type