Silicone Hydrogel Contact Lenses
Silicone hydrogel contact lenses, sometimes referred to as SiHy contact lenses, began to be introduced to the public in the late 1990’s. Since their introduction, they have been prescribed more and more by eye care professionals. SiHy lenses offer the wearer a more comfortable contact lens with the ability to stay moist even after long periods of wear. They also allow a longer wearing period without the potential for corneal damage.
Silicone hydrogel lenses contain less water than their older, non oxygen permeable contact lenses, the traditional hydrogel lens. Hydrogel lenses relied on the high water content to carry oxygen to the cornea, but the amount of oxygen that actually reached the eye was low, and the lenses were prone to dehydration after long periods of wear.
Silicone hydrogel contacts allow up to five times more oxygen to reach the cornea than non-silicone hydrogel lenses. Because silicone hydrogel lenses allow the eyes to receive more oxygen, many silicone hydrogel lenses have been approved for overnight wear, and are referred to as continuous wear lenses. Some lenses, like the Acuvue Oasys contact lens from Vistakon (Johnson & Johnson), are approved for up to 6 days of continuous wear by the FDA. There are even some silicone hydrogels that have been approved for up to 30 days of continuous wear. These 30-day lenses can be a good solution for patients who don’t want to have to deal with inserting and removing their lenses each day, and eliminates the need for contact lens solutions because the contact lenses will be thrown away after the 30-day period is over.
Even with the advantages that silicone hydrogel lenses offer, it is still important to adhere to the wearing schedule that is recommended by your eye doctor. Even though the lenses are approved for long periods of wear, if worn for longer than approved, they can cause serious damage, including eye infections and ulcers. However, if worn correctly, these lenses can provide patients with an alternative to Lasik surgery. Many patients that have considered Lasik surgery, but were deterred either by cost, or by anxiety at the idea of eye surgery, have found that continuous wear silicone hydrogel lenses satisfied their desire for clear vision with little to no hassle.
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