More and more people are into extended wear contacts. This can mostly be attributed to the fact that new technologies brought about better silicone hydrogel contact lenses which allow the eyes to breathe. These contact lenses are made of specialized silicone which allows oxygen to enter the cornea even during night time, allowing one to wear it for extended periods of time without taking the contact lenses off.
Similar Terms, Different Meanings
There are various terminologies about extended wear that should be clarified in order to properly define everything:
Flex Wear – A flex wear is a type of contact lens that can be worn overnight occasionally. It is a general term for most contact lenses. Example - Frequency 55
Extended Wear (EW) – it’s a type of contact lens that can be worn for 6 consecutive nights. Example - Acuvue Oasys
Continuous Wear (CW) – another type of contact lens that can be worn for 30 consecutive nights. Example - Air Optix Night & Day Aqua
It is a fact that the FDA has approval for extended wear contact lenses to be worn up to 7 consecutive days. One of the first optic lenses that was approved by the FDA as a Continuous Wear is the Air Optix Night and Day Aqua.
History of Extended Wear
During the 1970s, soft contact lenses emerge and were widely used by people from all walks of life as an alternative to wearing eye glasses. In the 80’s, more people were wearing contact lenses than eyeglasses and it was also during this period that the first Extended Wear contact lenses emerged and got approval from the FDA. However, several health complications emerged such as corneal ulcers and bacterial conjunctivitis due to wearing contact lenses continuously for 30 days which prompted the FDA to reduce the length of time to 7 days.
Originally, it was thought that the cause of the complications were improper maintenance and regular exposure to dirt and particulates. However, recent studies revealed that it was actually the lack of oxygen which is the main cause why corneal ulcers and conjunctivitis occur. Despite of this, it cannot be denied that contact lenses, no matter if they are extended wear or continuous wear, require proper disinfection and cleaning.
Air Optix Night & Day is approved for 30 days of continuous wear
Oxygen and the Cornea
Now that it was established that the cornea needs an adequate supply of oxygen to prevent complications, various brands emerged that are capable of allowing the cornea to breathe. Aside from this, added features such as the ability of to provide additional oxygen during night time also emerged.
This feature is called Oxygen Permeability which is measure in dK/L. The ideal dK/L value depends on the time of the day – 24 dK/L during daytime and 87 dK/k during night time. The more oxygen permeable the contact lenses are, the better. For example, the Air Optix Night & Day Aqua has a 140 dK value which is more than to enough supply the cornea with optimum amount of oxygen it needs.
Useful Tips for Wearing Contacts Overnight
Although extended lenses are the most convenient type of lenses because you do not have to go through the painful task of taking it on and off every day, it still needs regular care to be able to function efficiently. This is to prevent harmful bacteria and pathogens to become attracted to the warm and moist surface of the extended wear.
If you experience any irritation in your eyes, it is advisable to remove the contact lenses as soon as you can. You should also do this if you experience redness, blurry vision, pain or discharge. Leaving the extended wear in your eyes while experiencing the above conditions is the worst thing that you can do to your eyes.