Contact lens solutions will soon be required to have two new additions to their labeling. Although most manufacturers no longer label solutions “no rub” the F.D.A. will require rubbing lenses as part of disinfecting cycle on labeling for all multipurpose contact lens solutions. The other change will be to add a discard after opening date in addition to the expiration date already required..

Two separate incidences of outbreaks of serious eye infections the last several years have prompted theses changes. While the evidence points to non compliance with manufacturer recommendations of product use, it is felt that a higher error of margin needs to be built into the solutions regimens.

Testing of solutions is not as simple as you would think at first glance. Historically, the FDA has required two different methods of testing. Simplifying the process it can be viewed as primarily two different tests. The first is adding bacteria and fungal microorganisms to samples of the solutions and after the manufacturers specified time period for disinfecting they must reduce the number of bacteria by 99.9%  and the fungi by 90%. The second method of testing involves soaking the contact lenses in the microorganisms and then being disinfected as the manufacturer recommends. The lenses are then used to grow the bacteria and fungus on a special type of growth media. After a specific time period the number of live organisms are counted. These are referred to as colony forming units and less than 10 gives a passing grade. Tests must also be done to show that the solutions are not toxic or irritating to the eyes.

Bacteria chosen for testing in the past include Pseudomonas aerginosa, Serratia marcescens, and  Staphylococcus aureus. The first two are in a category called gram negative bacteria and the third is gram positive. Bacteria can be classified gram negative or positive by how their cell wall retains dye, and gram negative bacteria tend to be responsible for more serious infections. While most tropical and semi tropical climates show gram negative bacteria and fungal eye infections are more prevalent, temperate northern climates tend to have more gram positive bacterial infections associated with contact lens related eye infections. Pseudomonas is present almost everywhere in humid climates. While these three bacteria do cause a high incidence of contact lens related eye infections, there are numerous other bacteria that cause infections. While fungal eye infections are rare, Candida albicans and Fusarium solani are the two tested for. One of the recent outbreaks was caused by Fusarium.

We can’t test for every possible microorganism, the time and cost would be prohibitive. This is the best mix determined in the past. With Acanthamoeba being the organism resulting in the other recent outbreak it may be added to testing procedures in the future.

Reducing microorganisms to a level that the eyes immune system can handle is one assumption for test requirements. Bacteria are present at low levels at any given time in most peoples eyes. Many variables are left out of the testing protocols. The age of a lens may effect how well bacteria adhere. The condition of the contact lenses case, the wearers personal hygiene and individual variation in immune response, all factor in bacterial growth. The therapeutic dose of a disinfecting agent shows individual variation. Some bacteria mutate and become resistant to disinfectants, and also can develop coatings on the lens to render the solutions less effective. Some microorganisms may become more common, virulent, or our daily exposure to them may increase  for various reasons. For example, hot tubs have increased our exposure to acanthamoeba. The use of antimicrobial hand soaps may result in mutations to bacteria that were not a problem for the eyes in the past. Incomplete use and under dosing of antibiotic treatment may result in the same problem. The microorganisms used for testing are standardized and not necessarily representative of the current existing strain of that microorganism. Even the culture media used is standardized and different from the eye contact lens environment presented for the bacteria to develop in.

Rubbing a contact lens helps remove surface films and debris and allows the disinfecting solutions to work better. In the imperfect world of solution testing it is expected to help reduce eye infections.

The second change is more questionable. Solutions do have a lifespan when the disinfecting action drops below an effective level. They also could remain unopened until close to this date and then be used, resulting in usage past the time the solution was effective. Alternatively, once opened, the solution is subject to environmental contamination from bacteria that could exceed its capacity over time. The problem is putting two different dates on a bottle can be confusing. Proper wording can help, but one glance in any refrigerator will likely reveal we all aren’t very good at the two date dilemma. Time will tell, but short expiration dates on all solutions might be a better approach. Best of all would be a solution that changes into a horrible color after it has been open for a month. Of course with teenagers, that unfortunately might be an incentive to continue using it.

Contact lens solutions will soon be required to have two new additions to their labeling. Although most manufacturers no longer label multipurpose solutions “no rub” the F.D.A. will soon require adding a rubbing step to the care instructions. The other change will be to add a discard after opening date in addition to the expiration date for multipurpose contact lens solutions.

Two separate incidences of outbreaks of serious eye infections the last several years have prompted theses changes. While the evidence points to non compliance with manufacturer recommendations of product use as the cause, it is felt that a higher error of margin needs to be built into the solutions.

Testing of solutions is not as simple as you would think, with multiple requirements specified by the Food and Drug Administration. Simplifying the process it can be viewed as primarily two different tests. The first is adding bacteria and fungal microorganisms to samples of the solutions and after the manufacturers specified time period they must reduce the number of bacteria by 99.9%  and the fungi by 90%. The second method of testing involves soaking the contact lenses in the microorganisms and then being disinfected as the manufacturer recommends. The lenses are then used to grow the bacteria and fungus on a special type of growth media. After a specific time period the number of live organisms are counted. These are referred to as colony forming units and less than 10 gives a passing grade. Tests must also be done to show that the solutions are not toxic or irritating to the eyes.

Bacteria chosen for testing in the past include Pseudomonas aerginosa, Serratia marcescens, and  Staphylococcus aureus. The first two are in a category called gram negative bacteria and the third is gram positive. While most tropical and semi tropical climates show gram negative bacteria and fungal infections are more prevalent, temperate northern climates tend to have more gram positive bacterial infections. Pseudomonas is present almost everywhere in humid climates. While these three bacteria do cause a high incidence of contact lens related eye infections, there are numerous other bacteria that cause infections. While fungal eye infections are rare, Candida albicans and Fusarium solani are the two tested for. One of the recent outbreaks was caused by Fusarium.

We can’t test for every possible microorganism, the time and cost would be prohibitive. This is the best mix determined in the past. With Acanthamoeba being the organism resulting in the other recent outbreak it may be added in the future.

Reducing organisms to a level that the bodies immune system can handle is one assumption for test requirements. Many variables are left out. The age of a lens may effect how well bacteria adhere. The condition of the contact lenses case, the wearers personal hygiene, individual; variation in immune response, all factor in. The therapeutic dose of a disinfecting agent shows individual variation. Some bacteria mutate and become resistant to disinfectants and also can develop coatings on the lens to render the solutions less effective. Some microorganisms may become more common, virulent, or our daily exposure to them may increase  for various reasons. This is probably the case with acanthamoeba. The use of antimicrobial hand soaps may result in mutations to bacteria that were not a problem for the eyes in the past. Incomplete use and under dosing of antibiotic treatment may result in the same problem. The microorganisms used for testing are standardized and not necessarily representative of the current existing strain of that microorganism. Even the culture media used is standardized and different from the environment the eye contact lens environment presents for the bacteria to grow in.

Rubbing a contact lens help remove surface films and debris that allow a the disinfecting solutions to work better. In the imperfect world of solution testing it is expected to help reduce eye infections.

The second change is more questionable to me. Solutions do have a lifespan when the disinfecting action drops below an effective level. They also could remain unopened until close to this date and then be used, resulting in usage past the time the solution was effective. Alternatively, once opened, the solution is subject to environmental contamination from bacteria that could exceed its capacity over time. The problem is putting two different dates on a bottle is confusing. Proper wording can help, but one glance in any refrigerator will likely reveal we all aren’t very good at the two date dilemma. Time will tell, but short expiration dates on all solutions might be a better solution (pardon the pun). Best of all would be a solution that changes into a horrible color after it has been open a month. Of course with teenagers, that unfortunately might be an incentive.

Your Optometrist may have new guidelines for contact lens solutions in the future. The Food and Drug Administration has decided to review the testing procedures for contact lens solutions against the organism acanthamoeba. Acanthamoeba is a type of microorganism called a protozoa that thrives in moist environments and can be found almost everywhere, although it has a much higher incidence in regions with humid, warmer climates like the states in the South Eastern part of the country. Areas with low humidity like Colorado have a lower overall incidence. It is very common in most soil in addition to fresh water. Most forms of acanthamoeba do not effect the eye but one can with serious consequences. It is not unknown to find acanthamoeba when culturing contact lens cases of patients that are currently show no signs of infection. The eye has it’s own immune system including substances secreted in the tear film that can keep most infections from gaining a foothold. Contact lens wearers who over wear their lenses and use their solutions inappropriately are more susceptible to any type of eye infection. Over wear disrupts the tissue on the front of the eye, the corneal epithelium. This disruption allows organisms like acanthamoeba to enter into the eye tissue and multiply. The Centers for Disease Control and Prevention (CDC) confirmed 138 cases of Acanthamoeba infection of the corneal tissue (keratitis) in 35 different states during 1997. This type of infection has shown an increasing trend in recent years after slowing in the past when homemade saline solutions were discontinued. The increasing incidence may be related to the tendency to decrease or eliminate chlorination in drinking water although there are also many more people choosing contact lenses for their vision correction, and multipurpose solutions that are ineffective against acanthamoeba have become the contact lens care systems of choice. More contact lens wearers also mean more patients leaving their contact lenses on while enjoying a soak in a Jacuzzi. Chlorination of hot tubs is often inadequate; especially considering how frequently people overload the suggested capacity for occupants. Acanthamoeba exists in two forms and the cyst forms are very resistant to treatment. Unlike the active form the cysts can survive under extreme conditions of chemicals and large temperature ranges. Eye Doctors find acanthamoeba keratitis infections are difficult to treat and even with the care of the best corneal specialists they may still result in blindness and require corneal transplants. Acanthamoeba infections are almost unknown in the United States in patients who replace their lenses daily or don’t wear contact lenses. Hydrogen Peroxide contact lens cleaning systems kill the cyst form when used as directed. Chlorhexidine and heat systems will also kill the cyst form. Chlorhexidine is an older preservative fairly toxic to the corneal eye tissue and had a high incidence of allergic reactions when it was commonly used in contact lens solutions in past years. Heat disinfection bakes deposits on the lenses and was frequently skipped when it was the most common form of contact lens disinfection. All of these older cleaning systems have lower compliance rates and I believe 100% compliance with less effective solutions is better than 95% compliance with solutions having lower kill rates, especially considering the most common bacteria that cause keratitis are usually eliminated by multipurpose no rub solutions when they are used as directed. Using no rub solutions and adding back in a rubbing step on most days is a compromise that is probably the best system we have today. However, none of the multipurpose solutions have the capacity to effectively destroy acanthamoeba cysts. Hopefully the FDA review will help fill this gap in the future. In the interim the following guidelines like the FDA suggestions should help prevent most acanthamoeba eye infections.

(1) See your eye care professional immediately if you experience symptoms of eye infection such as redness, pain, excessive tearing, increased light sensitivity, blurry vision, and/or sensation of something in the eye.
(2) Wear and replace your lenses according to the schedule prescribed by Optometrist.
(3) Remove your lenses before any activity involving water, including showering, using a hot tub, or swimming.
(4) Wash your hands with soap and water for about 20 seconds, and dry them before handling your lenses.
(5) Clean your lenses according to the manufacturer’s guidelines and instructions from your eye doctor.
(6) Use fresh cleaning or disinfecting solution each time your lenses are cleaned and stored.
(7) Never use saline solution and rewetting drops to disinfect your lenses. Neither solution is an effective or approved disinfectant.
(8) Ask Your Eye Doctor about using a rubbing step with adequate rinsing even with no rub solutions. Rubbing the lenses removes surface deposits and has been shown to improve the disinfecting efficacy.
(9) Store your lenses in the proper storage case.
(10) Rinse your storage case with sterile multipurpose contact lens solution (never use tap water-it is a primary source of acanthamoeba) and leave the storage case open to dry after each use.
(11) Replace storage cases at least once every 1-2 months-you can usually find a case packaged with solution at no added cost.

Acanthamoeba is still a rare infection but hopefully will become unheard of in the future.

Dr David Kisling,O.D.

Fort Collins, CO. VSP Providor (Vision Service Plan))