Silicone Contact Lenses-What You Need To Know
The last 12 years have been a revolution in terms of contact lens materials.Adding silicone has allowed for over a 500% increase in the amount of oxygen passing through the lens to the cornea. Well over half of all new contact lens fits today are using these new materials. There are a few things you should know about this new generation of lens materials.
Silicone Hydrogel Contact Lenses Can Cause Problems
- Silicone enhanced contact lenses can cause problems. The material tends towards higher stiffness than normal contact lenses and has different characteristics. There has been an increase in giant papillary conjunctivitis with the increased use of silicone in lenses. The increased rigidity of the material interacting with the eyelid margins probably causes this reaction. The contacts start to stick under the upper eyelid and slide up with blinking. There are small bumps that develop under the upper eyelid that create discomfort. This is a non infectious process driven by an autoimmune response. Eye drops are often used to quell the inflammation, but it makes much more sense to use one of the older generation of materials. Giant papillary conjunctivitis was common in the early days of contact lenses when the same pair of lenses were worn for several years. As time went by the proteins, oils, and other components in the tears build up on the lenses over time. At some point, the deposits on the lenses elicit an autoimmune response and giant papillary conjunctivitis occurs. After the first wave of extended wear contact lenses surface in the 1980′s we started to see another increase in giant papillary conjunctivitis. These lenses also developed more deposits since they were being left in overnight and not cleaned daily. There may be a common component in all of these lenses of low grade irritation under the upper eye lid.
- Another issue with silicone enhanced contact lenses is an apparent reaction to the lens material. Patients tend to get red eyes that are uncomfortable. The eye has more of an allergic appearance. It is currently not clear what the true cause of this phenomenon is due to but switching to an older contact lens material seems to make it go away.
- The Third problem with silicone enhanced contact lenses is an interaction between the lenses and the solutions used to store them overnight. Some studies have found surface tissue damage accompanies common contact lens solutions, If you are fit into silicone enhanced soft contact lenses you should have your optometrist recommend a specific solution. Silicone blend contact lenses have some intrinsic problems in wetting. You need to follow the directions for contact lens solutions your eye doctor gives you. The way solutions are used may also help achieve higher comfort levels. Rubbing and rinsing lenses immediately after removal allows the solutions to increase wetting of the lens when you take it out in the morning. Washing your hands prior to handling lenses decreases the amount of oil and contaminants that may interfere with proper wetting of the contact lens surface.
- All contact lenses trap materials between the lens and the cornea on the surface of the eyes. Metabolic waste products, toxins generated from bacteria that live around the eye, and tear components can all get temporarily stuck under the lens.This is probably why we still see serious eye infections occasionally when people sleep in their contact lenses. While this situation is not much different from what occurs in a normal soft contact lens, it means you do not see all of the expected benefits from such an improve d lens technology.
Super Oxygen Contact Lenses Are Good For Your Eyes
- It’s not all bad! That 500% plus increase in air that passes through the lens to the cornea prevents premature aging of the cornea cells. Unlike older style contact lenses, the cornea cells maintain the same size and shapes that are present in young, healthy cells. There is almost no significant swelling of the tissue overnight (older extended wear contact lenses double swelling of the cornea overnight).
- Water beads up on silicone surfaces. Since you need water to spread out into a nice tear film for comfort, these lens have enhanced technology to improve wetting. The result has been lenses that generally wet better and have higher comfort levels than anything we have had in past years.
There are a few more things to work out with this new generation of soft contact lenses but they are wonderful addition for today’s contact lens patients who spends hours on the computer and have active outdoor lifestyles. Just remember, like everything else, occasionally older is better!