The Benefits of Silicone Hydrogel Contact Lenses
| Silicone Hydrogel Contact Lenses are the latest development in soft contact lens materials. They are healthier than conventional soft lenses because they allow up to 6 times more oxygen to pass through them and increased oxygen transmission results in better overall eye health. Advantages of silicone hydrogel contact lenses over conventional soft lenses include: |
The convenience of 30 days continuous wear (PureVision and Focus Night & Day), as well as the lowered incidence of eye health complications are quickly making silicone hydrogel contact lenses the most popular lens of choice for both eye care practitioners as well as patients.
Most eye doctors believe that within the next 5 years, more patients will be wearing silicone hydrogel contact lenses than any other lens material. The current brands of spherical silicone hydrogel contact lenses available, in order of highest oxygen transmissibility to lowest, are:
There are also currently two toric (astigmatism correcting) silicone hydrogel lenses on the market:
Studies have indicated that some lens care cleaning systems are compatible with silicone hydrogel contact lenses, while others may cause adverse reactions due to toxicity. Aquify, Optifree Express, and ClearCare multipurpose solutions have all been FDA approved to be used with silicone hydrogels.
AOSept has proven to be an acceptable hydrogen peroxide based system to use with these lenses.
In some studies, Renu Multiplus has been shown to cause an adverse corneal reaction when used with some silicone hydrogel contact lenses (source; Contact Lens Spectrum, August 2005). Additionally, UltraCare and SoloCare are not recommended for use with silicone hydrogel contact lenses.
Most people would benefit from wearing silicone hydrogel contact lenses as compared to conventional soft lenses due to the health advantages, however, these lenses are especially useful in the following types of patients:
Silicone hydrogels may not be the lens of choice for all patients. These lenses are generally more expensive than non-silicone hydrogel contact lenses so a more price conscious consumer may not prefer this option. Also, in some wearers, the silicone material tends to attract more lipid deposits, which may cause blurred vision and discomfort.
There are some cases where a patient is not able to adapt well to the more rigid silicone material, which may result in some minor defects to the corneal integrity. These complications are rare and generally the health advantages and increased comfort that most wearers experience far outweigh the incidences of adverse reactions in those who do not adapt well to the material.
Focus Night & Day were the subject of a three-year study by Ciba Vision. The company reported that the performance of this silicone hydrogel (SiHy) contact lens indicated that wearers enjoyed improved corneal health and reduced frequency and symptoms of contact lens related eye health symptoms.
In particular, the study of 317 patients showed that Focus Night & Day wearers had less problems with red-eye, reduced dryness (22%) and neo-vascularization (the development of new blood vessels in the cornea) was reduced by 13%.
During the first 8 months of 2005, Silicone Hydrogel contact lenses represented 24% of all soft contact lens sales – more than double the figure for the same period of 2004. Ciba lenses represented almost 50% of silicone hydrogel sales during this time.
Bausch & Lomb (manufacturer of Purevision, Purevision Toric and Purevision Multifocal contact lenses) reported that 40% of new contact lens fits are now silicone hydrogel contact lenses. They claim that 94% of wearers of their sector leading Soflens 66 Toric contacts can be migrated to the Purevision Toric lens without a script change.
Vistakon, manufacturer of the Ultra-Comfort series of contact lenses which comprises the Acuvue Advance, Acuvue Advance for Astigmatism and the Acuvue Oasys says their silicone hydrogel contact lenses are all addressing the issue of end-of-day comfort for contact lens wearers.
Prescription parameter ranges are being expanded for each of these lenses (most recently, plus powers for Oasys were made available). Acuvue Oasys was also recently given FDA approval for up to 7 days of continuous wear. Vistakon claims to have the number one silicone hydrogel contact lenses with their Acuvue Advance and the number one new-wearer toric in the Advance for Astigmatism.
[2006 AC Lens, Reproduction Prohibited without Express Permission]
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