Soft contact lenses can irritate your eyes in a number of different ways.
Allergies to the preservatives in solutions still occur, but not as commonly as in years past.
Thimerosal, (sodium ethylmercurithiosalicylate) is a preservative whose composition is about half mercury. It as commonly used in very low doses in contact lens disinfecting solutions and is an excellent preservative but causes a reasonably high number of allergic reactions. It has been used in childhood vaccines and a subject of controversy over the years as being related to autism. There are no significant studies to confirm a relationship but similar to contact lens solutions, it is being phased out, and many parents still believe it is a primary cause of autism..
Chlorhexidine is a chemical antiseptic that is very effective at killing bacteria. It was also widely used in the past in contact lens solutions but caused red eyes, vague forms of irritation, and sometimes significant eye irritation and discomfort. Like Thimerosal, it has largely been phased out. It is still widely used in the dental field to treat gum disease and as a disinfectant.
Benzalkonium chloride was used in the past and is still used today is some nasal sprays, cleaning solutions, and various other hygienic products. It is a good disinfectant but at high enough levels may not only serve as an allergen but cause serious damage to the corneal tissue the contact lens rests on.
The next generation of sensitive eyes contact lens solutions proved to have about the same rate of allergic reactions, just for different people. Switching often cured the problem for those allergic to former solutions but created problems for new users.
Many generations of solutions have since come to pass. Today the large molecule preservatives are favored since they fail to build up in the lens matrix, exceeding the pore size of the lenses.
The problem today rests in generic solutions, often colored and labeled to look like the brand solutions. Sometimes they are OK, at other times they are using these older toxic preservatives that should have been off the market a long time ago. To compound the confusion, the formulations may change in the middle of the shelf for the same generic brand, even though the box appears identical.
The best bet today is to stick with a brand name solution or use one of the hydrogen peroxide based systems. The drawback to hydrogen peroxide has always been it is too easy to make a mistake and hydrogen peroxide is very uncomfortable when placed in your eye without neutralization! Ask you family optometrist for recommendations and express any cost concerns you may have. then stick with what they suggest to protect your eyesight from hidden dangers of toxic solutions.
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information presented herein intended to substitute for the advice provided to you by any health care or other professional
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