We still see allergies to the preservatives in contact lens solutions in our Fort Collins Contact Lens Clinic but at a much lower frequency than in the past.

Thimerosal, (sodium ethylmercurithiosalicylate)  is an older contact lens solution preservative whose composition is about half mercury. It as commonly used in very low doses in contact lens disinfecting solutions 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 a possible cause of autism. There are no significant studies to confirm a relationship,  but similar to contact lens solutions, it is being phased out. You will often see vaccines that are touted as mercury free.

Chlorhexidine is a chemical antiseptic that is very effective at killing bacteria. It was also widely used in the past in contact lens solutions prescribed by eye doctors but frequently caused red eyes, vague forms of  eye irritation, and sometimes significant conjunctivitis and  discomfort. Like Thimerosal, it has largely been phased out of contact lens care and we never reccomend it in our Ft Collins Eye Practice. 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 by optometrists since they fail to build up in the contact lens matrix, exceeding the pore size of the lenses.

The problem today rests in generic contact lens 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 your eye doctor reccomends 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!

Spend a few extra minutes during your next visit to the optometrist and ask their advice on what is the best contact lens care regimin avaialbe to keep your eyes healthy and seeing well.

SIX SIGNS YOU MAY HAVE GPC

FROM YOUR CONTACT LENSES

• Itchy eyes as contact lenses get older

• Lenses that slide and stick under the upper eye lid

• Irritation Every Time You Blink

• Mucous Discharge and Foggy Vision
  

• Lenses That Discolor and Develop a Film
  

• Intermittent Red Eye With Feeling Something is Scratching Your Eye
  

In the early years of soft contact lenses there was one choice, the Bausch & Lomb Soft Lens. The cost of a single pair of these miraculous new soft, comfortable lenses was between $300 and $400 when first introduced in 1971. Accounting for inflation, today that would be almost $2000. There was a very strong financial incentive to make the lenses last as long as possible. Using enzyme cleaners and sending lenses off for a special factory cleaning were common procedures. Lenses were often used for 3 to 4 years until they were yellowed and covered with numerous deposits from components of the tear film. Lipid bumps, calcium and mineral deposits, protein deposits and frequent tears and little missing chunks of the lens edges were tolerated well past the healthy tolerance of the eyes.

A new eye problem begin to show up in a number of the wearers of these new soft contact lenses. As lens technology progressed and prices came down lenses were replaced more frequently and the mystery red eye syndrome seemed to drop off. Then in 1981 the Hydrocurve soft contact lenses was introduced as the first contact lens for over night wear, the advent of extended wear contact lenses.  Cases of this new eye problem started to show up again and become common enough to recognize and diagnose.

The typical patient would come in to see the optometrist complaining about eyes that were red and irritated, possibly itching, and contact lenses that would slide around on the eye, sometimes falling out with blinking. On further questioning the lenses usually were sliding up as they would occasionally adhere to the underside of the upper eyelid. Frequently there would be some clear mucous or discharge from the eye, and some contact lens wearers would tell their eye doctor they kept seeing little spots on the surface of the lenses when they were handling them.

People have often admitted to me they turned their upper eyelids inside out as kids. For some unknown reason, girls more than boys, at least by admission. What was found in the 1980′s when inverting the upper eyelid is now referred to as Giant Papillary Conjunctivitis, or GPC. Usually it is referred to as GPC. There is a clear tissue that covers the white scleral part of your eye and extends underneath the eyelids as their surface lining. In GPC, giant papillae  (bumps of swollen tissue) form under the upper eyelid. These are described as giant but actually are about 1/3 millimeter in diameter. They do feel giant due to the highly sensitive nature of the clear tissue on the front of your eye, the cornea. Every blink rubs these bumps across the cornea and creates discomfort.

The cause of GPC has been disputed for years but most eye care providers agree there are two components, a mechanical irritation and an immunological reaction.

The lens edge constantly engages the underside of the eyelid with each blink that results in a form of low grade irritation and inflammatory reaction in a small percentage of contact lens wearers. There are probably multiple reasons such as how taunt or floppy the lid is, how the secretions make it more prone to slide over or stick to the lens, the variations in lid curvature that apply pressure to the lens at different areas, and if the conjunctiva tissue has a higher number of inflammatory mediators already present. Deposits on the lenses can also cause a mechanical type of reaction.

The immunological reaction is related to deposits that build up on the lenses. These can be your own tear lipids,proteins, preservatives in contact lens solutions that build up in the lens matrix, environmental allergens that build up on the lens, and in rare cases possibly the material the lens is made of. Since soft lenses are about half water they act like a sponge absorbing larger molecules and retaining them resulting in increasing levels over time.

Wearing the same pair of lenses for several years obviously caused an increase in this condition.  The hard lenses worn prior to soft contact lenses can still cause GPC, but because they are inert and do not absorb any water the incidence is very low. With the advent of extended wear, the eyes were given constant exposure to the mechanical and immunological irritants with no recovery time so the incidence started climbing again.

In the first era of contact lens technology lenses were frequently machined on a lathe when dry then re-hydrated. Bausch & Lomb developed spin casting the liquid material in a mold. Today automation and molding manufacturing techniques allow for much more precise and smooth lens edges. Lens that were hand inspected under a microscope in the past are now quality controlled by automated systems. These have been quantum  improvements in lens quality that have helped decrease lens edge induced GPC problems.  Extended wear contact lens materials are starting to be designed today to help resist deposits better.  For a number of years now the major contact lens manufacturers have been using large molecule preservatives that exceed the pore size of soft contact lenses. This greatly reduces the possibility of toxic preservatives inside the lens over time. Unfortunately, many generic solutions appear similar but often contain the older small molecule preservatives that can lead to GPC.

Even though the occurrence is much lower today, GPC can still be a major eye irritant and contact lens problem. There are several approaches to managing GPC. Switching to daily disposable lenses eliminates coating reactions completely since the lenses are thrown away daily and never exposed to disinfecting solutions. Usually, contact lens wearers with GPC have been wearing their contacts well beyond the suggested replacement cycle and become lax in cleaning the lenses. Returning to a normal 2-4 week replacement cycle and  discontinuing or decreasing overnight wear may be all that is required to return the eye to normal health.

Prescription eye drops are also a large part of treating GPC. A class of eye drops called mast cell stabilizers work to stabilize the cells membranes from releasing histamine that starts the inflammatory cycle. These eye drops are very safe and can be used year round when needed. Other options are available and today GPC is no longer the end of your contact lens career, only a small bump in the (eye) road.  Vision Insurance like Vision Service Plan Frequently offer plans that include medical treatment for conditions like GPC. You should do an annual review of all of your medical and vision coverage to make sure you are providing the best benefits you can for your family.