on Thursday, March 25, 2010
We have embraced technology in every aspect of our lives – why not take advantage of the technological advances made in contact lens materials? I’d like to talk about two technological advances in contact lens material, each with unique benefits – silicone hydrogel and PC technology.
Silicone hydrogel contact lenses are the most recent development in soft contact lens materials. Silicone is a material that is highly permeable to oxygen. By placing a contact lens on the eye, the amount of oxygen that reaches the cornea is reduced. As a certain amount of oxygen is necessary to maintain corneal health, by incorporating silicone into the contact lens material, a sufficient amount of oxygen can easily travel through the lens and reach the cornea.
The trade off to silicone in a contact lens is that silicone is hydrophobic. That means water will not spread easily across the lens surface, making it difficult to keep the lens wet. That makes a lens uncomfortable. Silicone in a lens also makes it a stiffer material which can reduce comfort as well as irritate the under side of the upper lid. A lens that contains silicone is prone to get deposits on the surface of the lens thus reducing comfort yet again. It is no surprise that the number one reason why people stop wearing contacts is due to discomfort.
As with all technology, improvements are continually being made. Silicone hydrogel contacts have been available since 1999. Each successive generation of silicone hydrogel material brings improvement in the comfort of the lens and overcomes earlier limitations. For example, in prior versions, different coatings or lubricant additives were used to try to improve the lens wettability. The most recently developed silicone hydrogel lenses, which are made by CooperVision, utilize an entirely new silicone hydrogel material. This new material is naturally wettable and does not need coatings or additives. It is also a very soft material and is resistant to certain deposits both of which offer improved comfort.
Biofinity (a monthly replacement lens) and Avaira (a two week replacement lens) are CooperVision’s contact lens brands that are made with the newest silicone hydrogel materials. They have high oxygen permeability, are very soft, are resistant to getting deposits and are very comfortable. Ask your eye care provider if you are a candidate for Biofinity or Avaira contact lenses.
No matter your physiological profile, we have a lens for you. Stay tuned for the next post about CooperVision’s revolutionary lens materials!
on Thursday, December 31, 2009
“DEFENSE!! DEFENSE!!” is frequently shouted during basketball and football games. Defense, according to dictionary.com, is a noun meaning protection and resistance against attack. But what does defense have to do with contact lenses? Think of replacing your contact lenses at the interval prescribed by your eye care practitioner as your DEFENSE when wearing contact lenses.
Defense against what? A common misconception is that tears are made of only water. While water is the main component, there are actually hundreds of substances found in tears. Other important components include mucins (natural lubricants), oils, electrolytes (such as sodium chloride and potassium) and proteins (that defend against bacteria and other organisms). As soon as a lens is placed on the eye, it will start to absorb some of these components, particularly proteins and oils. Over a short period of time, deposits can form on the lens. Deposits reduce comfort and vision and can cause allergic-type reactions, particularly under the upper lid. Deposits also reduce the amount of oxygen that can pass through the lens. That can cause changes to the outer layer of the cornea that may allow bacteria or other organisms to infiltrate the cornea and cause an infection. The amount of deposits will vary depending on the contact lens material and the tear composition of the individual. For example, some people naturally have more protein in their tears than others. Some lens materials are more resistant to protein deposits than other materials.
An eye care practitioner will select a replacement schedule for a patient after a careful evaluation of the patient’s ocular health, tears, lifestyle and the contact lens material. The idea is to replace lenses before deposits form and before any problems develop. Even if a lens is still comfortable at the end of the replacement period it should still be replaced. Many contact lens related problems are only evident to the eye care practitioner and not the wearer.
For those of you who wear one day lenses, it is easier to remember when to replace them as you discard your lenses after each day of wear. It is more difficult to remember to replace lenses on a two week or a monthly cycle. We suggest writing the prescribed replacement date on a post it note and placing it on the mirror in your bathroom or on your computer screen. If you are digital, put a reminder in your Outlook or iCal calendar. Syncing up your replacement schedule with natural habits helps maintain comfortable and healthy contact lens wear!
Replacing lenses on the schedule prescribed by your eye care practitioner will minimize complications, maximize comfort and contribute significantly to successful contact lens wear. Whether you replace your lenses each day, every two weeks or every month, remember to chant “DEFENSE!! DEFENSE!!” when you discard those lenses at the proper time.
If you have any great tips on how you remember to change your lenses, please comment on this post so we can all benefit from your suggestion.