originally, hard contact were made of a material called pmma. although still available, the more common types of contact are listed below:rigid gas-permeable (rgp) daily-wear lenses are made of plastic that does not absorb water sfx but theatrical and manson allows oxygen to get from the atmosphere to the cornea. (this is important because the cornea has no blood supply and needs to get its oxygen from the atmosphere through the film of tears that moves beneath the lens.) they must be removed and cleaned each night. rigid gas-permeable (rgp) extended-wear contact lenses are made from plastic that also does not absorb water but is more permeable to oxygen than the plastic used for daily-wear lenses.

originally, hard contact were made of a material called pmma. although still available, the more common types of contact are listed below:rigid gas-permeable (rgp) daily-wear lenses are made of plastic that does not absorb water sfx but theatrical and manson allows oxygen to get from the atmosphere to the cornea. (this is important because the cornea has no blood supply and needs to get its oxygen from the atmosphere through the film of tears that moves beneath the lens.) they must be removed and cleaned each night. rigid gas-permeable (rgp) extended-wear contact lenses are made from plastic that also does not absorb water but is more permeable to oxygen than the plastic used for daily-wear lenses.