What are continuous wear contact lenses?

As anyone who has been sourcing online contact lenses for a few years will know, contact lens technology continues to develop.  As new materials with different properties are discovered the possibilities for innovation expand, resulting in both an ever greater range of online contact lenses hitting the market, and older technologies being replaced. Silicone hydrogel is one of these relatively new materials that has made it possible to make continuous wear contact lenses a mainstream addition to the range of online contact lenses now available.  This is in contrast to the time when continuous wear contact lenses were a bit of a niche product, and unsuitable for many people.  But just what does ‘continuous wear’ actually mean?

Perhaps the most important point to note with continuous wear, and indeed any type of contact lenses is that the period of time that you can wear these products is determined by a professional assessment of your eyes.  Thus the replacement schedule for exactly the same type of contact lenses can vary from person to person, and so you should always seek the advice of your optometrist (optician) or ophthalmologist (eye doctor) before trying out a new type of lens and replacement schedule.

Continuous wear contact lenses can be seen as an evolution of extended wear contact lenses.  Extended wear contact lenses were first introduced in the early 1980’s.  The ‘extended’ part meant that the lenses could be worn overnight, in contrast to the majority of existing contacts which were designed for daily wear, and needed to be removed prior to sleeping each night.  Some extended wear contact lenses were approved for 6 days continuous wear, others for 2 weeks, and soon a whole month of continuous wear was tried, with varying degrees of success.

The main issue with the potential to cause complications was the amount of oxygen that the lenses let through to the eyes.  Restricted oxygen transmission could create favourable conditions for a number of different bacteria to multiply under the lens, and eye doctors noticed that when extended wear contact lenses were first worn continuously for up to a month, the number of patients developing eye infections and other problems increased.

Silicon hydrogel was the breakthrough material – first used in the late 1990’s – which allows much more oxygen to reach the eyes than older materials.  This super permeable substance is now used to create disposable continuous wear contact lenses, which can be worn day and night without removal for up to 30 days (as determined by your eye doctor).  Throwing the lenses out after this time also helps alleviate another problem previously faced with older non-disposable lenses, such as RGP (Rigid Gas Permeable) lenses.  RGP lenses can be compromised by a build up of protein and lipid on lenses which can be hard to entirely get rid of, even with a tailor made solution.