Rigid Gas Permeable (RGP) contact lenses are hard lenses that allow oxygen to pass directly through the lens material to the cornea. RGP lenses provide stable, clear vision and are easy to care for. 

RGP lenses typically provide sharper, more stable vision than soft contact lenses. They are also easier to handle and care for than most soft contact lenses.

Unlike soft contact lenses, RGP lenses are custom made to specifications provided by your eye care professional. They can be modified during the fitting process to tailor the fit of the lenses perfectly to the shape of your eyes. 
Wearing Schedule
There are two types of RGP lenses based on wearing schedule: 
daily wear and extended wear.
Daily wear RGP lenses are removed at the end of the day for cleaning and disinfecting. They are not approved for overnight wear.
Extended wear RGP lenses can be worn overnight and are approved for up to several days of continuous wear.
Lens Power Design
There are three types of soft lenses based on power design: 
spherical, toric, and multi-focal. 
Spherical  Spherical RGP lenses correct nearsightedness, farsightedness, and astigmatism. RGP lenses retain their shape on the eye. Therefore, spherical RGP lenses can correct astigmatism. (Soft lenses conform to the shape of the cornea and must have a toric design to correct astigmatism.)
Toric  Toric RGP lenses have a more sophisticated design to correct high amounts or unusual types of astigmatism.
Multifocal  Multifocal RGP lenses are available in bifocal and multifocal designs to correct presbyopia.
Lens Tints
RGP lenses are available with a light "locator" tint (usually blue). Locator tints don't change the color of your eyes, but they make lenses easier to find if you drop them. Since RGP lenses are small and move noticeably with blinks, RGP lenses with darker tints don't look as natural as tinted soft lenses and therefore are not recommended.
Visi Tint  Visi tints or locator tints don't change the color of your eye, but make your lenses easier to see and find.
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