Rigid gas permeable contact lenses are non-disposable lenses made of rigid materials. They’re custom made and they’re particularly useful for high prescriptions, unusual eye conditions and irregular eye shapes. Rigid lenses are used for for fitting people who have had corneal grafts and people with keratoconus. They provide excellent clarity of vision, and are an option for less exotic prescriptions too although they require a longer period of adaptation than soft lenses. Orthokeratology (a process of reshaping the eye surface overnight in order to see clearly during the day without contacts or glasses) involves wearing rigid gas permeable lenses overnight. Gas permeable contact lenses offer excellent long-term corneal health since they allow almost as much oxygen reach the eye surface as not wearing a lens.
Nearly all rigid lenses in the twenty first century are made from gas permeable materials and should be replaced every year or two. Hard lenses made last century have a very long life span but provide less oxygen to the eye surface. Wearers of all kinds of contact lenses should have eye exams annually.