Contact Lens



             


Monday, January 9, 2012

Contact Lens Types

Soft contact lenses have been released in many different formats since they were first developed in the 1960s.

Soft contact lenses were originally designed to be worn for 12 to 18 months and removed nightly. These contact lenses are now called ?conventional soft contact lenses?. They are usually prescribed as a specialty lens and are generally used when frequent replacement or disposable contact lenses are not available. They have the disadvantage of being more expensive and tend to accumulate surface deposits. This mode of lens wear requires more diligence with cleaning and care.

Disposable contact lenses were first released commercially in the 1980s. The first disposable lens was the Johnson and Johnson Acuvue contact lens, which was a 2 week disposable contact lens. It was a soft hydrogel lens and was primarily worn on a daily basis. The original Acuvue contact lens has only recently been discontinued. It was designed to be replaced after 2 weeks of daily wear.

Soft disposable silicon hydrogel contact lenses were first available in the 1990s. The first silicon hydrogel lenses offered were the B&L PureVision and Ciba Focus night & Day lens. Both these lenses are approved for one month extended wear. Silicon hydrogel contact lenses have the advantage of greater oxygen permeability than the original hydrogel contact lenses. Approximately 98% of patients are able to wear this type of contact lens. There is however, a slightly increased chance of developing microbial keratitis or corneal ulcer with this mode of wear. Some studies place the risk at one in five hundred per wearing year.

The next generation of silicon hydrogel soft disposable contact lenses saw the release of Ciba Optix O2 and Johnson and Johnson Acuvue Oasys. These lenses have an improved surface treatment, which leads to improved hydration and increased comfort.

More recently daily disposable soft hydrogel contact lenses have become increasingly popular. These lenses, such as J&J 1-day Acuvue Moist and CibaVision Focus Dailies have the advantage of being more hydrophilic and retaining moisture during the day.

Focus Dailies contact lenses contain AquaRelease to improve hydration and are replaced daily, leading to increased comfort from a cleaner lens. Daily replacement lenses also have the advantage of lower complication rates due to the lenses developing less surface deposits and lower infection rates. Obviously a contact lens case is superfluous with this mode of lens wear. Contact lens cases have been found to be a major source of microbes that can cause eye infections.

Contact lenses are now also available to buy online, meaning a faster, cheaper and more convenient alternative in purchasing your lenses. Contact lens wearers should still maintain a responsible attitude to lens wear, and have their eyes checked regularly by their eyecare practitioner. They should also check their own eyes daily for eye infections, by following the ?Look OK, See OK, Feel OK? regime. Each morning after inserting the lenses they should check each eye look white, then check the vision in each eye separately, and then blink once or twice and ensure there is no discomfort. If there is any change, they should remove the lenses immediately and consult their eye care practitioner.

Bruce Macnaughton is a freelance author who writes about online contact lenses and recommends Webcontacts.com.au.

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