Silicone hydrogel contact lenses are soft contact lenses made from silicone. Since this material allows oxygen to pass through, silicone hydrogel lenses enable more oxygen to reach the eyeballs. Therefore, the eyes are less likely to become irritated. More and more extended wear contact lenses are being made from this material for this reason. Unfortunately, these types of contact lenses generally cost more than other types, and they may require special cleaners.
Typical soft contact lenses are made from soft, flexible plastic that also contains water. For oxygen to reach the eyeball, it must combine with the water and travel to the surface of the eyeball. This can result in insufficient amounts of oxygen reaching the eye.
Silicone hydrogel lenses are made from silicone, which is also a type of plastic. Unlike regular soft contact lens materials, however, silicone is gas permeable, meaning that oxygen is able to pass through it. Oxygen is also carried to the eyes when it attaches to the water molecules in the lenses. This results in much more oxygen reaching the surface of the eye.
Most people who wear silicone hydrogel lenses will find that their contacts are less likely to dry out after they are worn for extended periods of time. Also, when the eyes are deprived of oxygen for prolonged periods of time, blood vessels that deliver oxygen to the cornea will begin to grow. When this happens, the eyes appear very red.
Since silicone hydrogel lenses allow more oxygen to reach the eyes, they are generally best for people who wear contacts for long periods of time. This is especially true for people who sleep in their contacts, a habit that is often discouraged by optometrists. In fact, most extended-wear contact lenses are now made from silicone. These types of contacts can be worn for weeks or months at a time.
Although there are many advantages of silicone hydrogel lenses, there are also some disadvantages. For instance, they are often a bit more expensive than other types of contact lenses. They may not be worth the extra money to individuals who remove their contacts every night.
Some multipurpose contact lens solutions are not recommended for use with silicone hydrogel lenses either. Using these non-compatible contact solutions can result in corneal abrasions and inflammation. When cleaning and storing silicone hydrogel contact lenses, it is important to use a contact solution that is compatible with these types of lenses.