Advantages Of Conventional Hydrogel Contact Lenses Materials

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Definition: First, let’s know about Conventional hydrogel contact lenses materials. They are polymers. The commonest of these is the first hydrogel material used for contact lens wear, poly (2-hydroxyethyl methacrylate) or polyHEMA (HEMA). PolyHEMA is cheap to produce, highly flexible, stable to changes in pH and temperature and has proved to be a very successful contact lens material. The main disadvantage of polyHEMA is that water has limited ability to dissolve and transport oxygen, with approximate oxygen permeability (Dk) of around 80 Dk units. In order to increase the Dk of a conventional hydrogel contact lens material, it is necessary to incorporate monomers that will bind more water into the polymer. These higher water content …show more content…

As seen in one study which aimed to report a series of consecutive cases for which a lotrafilcon A silicone hydrogel soft contact lens was used in therapeutic applications (Montero, 2003). The result of this study was “complete pain relief was reported for 78% of cases with 94% reporting pain relief of 50% or more. Corneal signs were restored to normal for 74% of cases with 100% showing at least partial improvement. No additional complications were reported in 83% of cases. Therapeutic contact lens application was judged fully successful for 71% of cases with 93% showing at least partial success.” (Montero, …show more content…

More oxygen means healthier cornea, free of hypoxic effects and able to overcome common contact lens complications. A study of (Fonn, 2006) reviews some contact lenses complications and how silicone hydrogels address them. In case of corneal edema, studies approved a strong relationship between corneal swelling and oxygen transmissibility. Contact lenses enhance corneal swelling if they are worn overnight; the amount of swelling has been estimated in between 7% to 15% in wearing low-Dk hydrogel lenses 11. Many studies (Fonn, 2005) (du Toit, 2003) have shown that silicone hydrogel CL induce significantly less overnight corneal swelling (2% to 5%) than conventional low-Dk hydrogel lenses which is almost similar to the normal overnight (closed-eye) corneal swelling without contact lens

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