Types of Contact Lenses
Ever wonder what contact lenses are made of? We all know how uncomfortable it can be to get a foreign particle stuck in your eye, so how is it that lenses actually feel good? What could they possibly be made of? Here’s the many types of contact lens materials that exist:
The most popular type of contact lenses today, soft contact lenses, are made of a hydrophilic plastic. That’s a special type of water-absorbing plastic that will stay moist in your eye, all day long.
The crazy thing about this material though is what happens when it gets dry. Ever had a lens dry out? It gets really brittle. That’s because the lens material depends on moisture to stay pliable.
If you wear your contact lenses overnight or for a week at a time, there’s a good chance your lenses are made of a silicone hydrogel. This is a combination of water-absorbing plastic with silicone.
Adding the silicone to the hydrogel plastic creates a lens that not only stays moist but also allows more oxygen to transmit through the contact lens into the eye. This keeps the eyes healthier. Any contact lens wearer who is keeping a lens in all day and night, or for a week at a time, needs to be wearing a lens that allows their eyes to breathe.
Rigid Gas Permeable Lenses
Rigid gas permeable lenses (RGP lenses) are also made of plastic. Unlike the plastic that makes a soft contact lens, the rigid gas permeable lens transmits oxygen without absorbing water. RGP lenses contain microscopic holes to filter oxygen through. Most RGP lenses are now made of three main materials: acrylate, silicone and fluorine.
Though RGP lenses are sometimes called “hard” lenses, they aren’t like the “hard” lenses of decades ago that were made mostly of acrylate and are no longer prescribed because not enough oxygen could get through this type of material.
Hybrid Contact Lenses
Though hard to find, there is a hybrid contact lenses that combines the materials of an RGP lens and a soft contact lens.
These lenses have the acrylate-silicone-florine combination in the middle, for sharpened central vision, with the soft contact lens water-absorbing hydrogel around the edges for better comfort.
These hybrid type lenses are often used for multi-focal lenses (bifocal or progressive contact lenses) or for treating irregular astigmatism.