The idea of lenses made from plastic hydrogel was first proposed more than 20 years ago. The possible benefits were clear but the technical problem was as hard as needing to mix water and oil to produce an optically clear product. Researcher agencies have-to date used considerable educational and financial resources to achieve the high end soft lenses of to-day. They've done this basically because they see this material while the way forward and the supreme standard into the future.
At the time of writing, silicone hydrogel lenses are available in the USA from four manufacturers: 'Night & Day' and 'O2OPTIX' from CIBA Vision, 'Pure Vision' from Bausch & Lomb, and 'Acuvue OASYS' and 'Advance' from J&J Vision Care.
So whats so particular about plastic hydrogel as a contact material? Essentially, the truly amazing benefit of this substance is its capability to transport oxygen to the eye and hence maintain proper eye health. Modern lens technology is all regarding air permability, that is measured utilizing the 'Dk' index. Browse here at webaddress to study the inner workings of it. And for optimal oxygen indication, this must be as high as you can. Identify more on a partner article directory - Click here: how to use butt plug.
The Dk of conventional, non-silicone based hydrogel lenses is directly linked to the level of water that the material can take, because air dissolves in to the water-component of the material and therefore diffuses through the lens. The Dk actually increases logarithmically with increasing water content. Water itself-has a Dk of only 80, thus setting a limit on the Dk of convential supplies, and the original soft lens material, polyHEMA, includes a Dk of only around 10 (using a water content of about 38%).
Nevertheless, in silicone hydrogels, the partnership between Dk and water content is the other. Here higher water content implies lower Dk. With these contacts Dk increases somewhat since the plastic content - not water content - of the lens increases. The Dk values of silicone hydrogel lenses are greater than those of older soft lens materials.
RESTING IN CONTACT LENSES
According to market data from CIBA Vision, 84% of soft lens wearers occasionally sleep with their contacts in, and one-third admit to doing this often. 2500-10 of wearers of 1 to two-week disposable lenses with low-oxygen transmissibility sporadically or routinely rest within their lenses overnight. And 72-par of soft contact lens wearers said they'd prefer to be permitted to wear their lenses overnight provided it was safe.
Hence the demand for lenses with the capablities of silicon hydrogels is evidently high with almost three-quarters of soft lens wearers hoping to be able to settle their lenses.
Silicone hydrogel lenses are a lot more rigid than their traditional counterparts, as a result of presence of silicone. This increased stiffness does possess some advantages, making the contacts considerably simpler to manage and ergo the best choice for consumers with a less delicate touch. There is a downside to this however in that the rigidity makes the lenses less prone to using the condition of the eye therefore quickly, resulting in the likelihood for a few of reduced ease.