• Both silicone hydrogel contact lenses and RGP contact lenses are oxygen permeable.contact lens image by vladislav susoy from Fotolia.com
  
  Oxygen-permeable soft contact lenses are sold on the market as silicone hydrogels. These differ from RGP (rigid gas permeable) contact lenses in that RGP's are hard lenses. Both lenses allow oxygen to pass through to the eye, which is said to be healthier for the wearer. Silicone hydrogels do have their advantages, but there are also some significant drawbacks.
  
  

Expense

• Silicone hydrogel lenses are traditionally more expensive than their non-silicone alternatives.money image by Horticulture from Fotolia.com
  
  According to AC lens, silicone lenses are generally pricier than their non-silicone alternatives. A patient who is concerned about cost may want to choose a contact lens that is non-silicone to avoid the higher price. Some insurance companies also do not cover silicone lenses.
  
  

Deposit Buildup

• These particular contact lenses are prone to deposit buildup.contact in case image by Melking from Fotolia.com
  
  Contact Lens Monthly touches on surface treatment and lipid interaction as problems with silicone hydrogel contact lenses. Lyndon Jones, PhD, in his editorial on SiliconeHydrogel.org, discusses this in greater detail. These lenses are designed to be worn for up to 30 days without interruption. When tears interact with this silicone hydrogel material over time, "hydrogel materials rapidly spoil with constituents from the tear film, particularly proteins, 25, 26 lipids 27 and mucins," states Jones. These deposits can cause problems such as inflammation, irritation and visual complications. Jones discusses how contact lens companies have improved the silicone hydrogel material, developing material that will reduce the amount of deposit build up that accumulates on the lenses, although buildup still occurs.
  
  

Health Complications

• Eye infections are the main health complication associated with contact lenses.green lens 2 image by Bosko Martinovic from Fotolia.com
  
  As with any contact lenses, there is a greater risk of eye infection such as conjunctivitis (pink eye). With silicone hydrogels, the risk for some infections is greater because the lenses are worn overnight, for 30 days at a time. According to All About Vision, the risk of most infections is no greater with silicone hydrogels than it is with any other contact lenses. There is a specific, rather dangerous infection that has been associated with the use of silicone hydrogel contact lenses. All about vision acknowledges that the risk of microbial keratitis is slightly higher in wearers of silicone hydrogel lenses. Eye Journal discusses four cases of microbial keratitis, both in wearers of silicone hydrogels. The Eye Journal pegs the infection the worst vision complication associated with contact lenses wear. The four patients discussed in the journal experienced pain, eye abscesses or ulcers, redness and even temporary blindness. Three out of four of the patients suffered permanent changes to their vision.