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What's Bugging Contact Lens Care Solutions?

Understand solutions and the proper care of contact lenses.

EUNICE MYUNG-LEE, O.D., F.A.A.O. AND HARUE J. MARSDEN, O.D., M.S., F.A.A.O.

In 2006 and 2007, the eyecare industry experienced significant public-health issues relating to the safety of contact-lens wear, following an increase in the incidence of fungal eye infections and reports of Acanthamoeba keratitis.^1,2 Throughout the healthcare industry, manufacturers recalled products because of the risk of contamination or negative side effects. Debate regarding the safety and efficacy of lens-care products has been heavy, as has the blame associated with non-compliance. Putting fault aside, it's worthwhile to review the factors involved in the research and development of contact-lens solutions. We may then use this information to provide our patients with the most effective contact lens care regimen.

THE "PERFECT STORM"

Initial fear during this period was that the solutions themselves were contaminated, which led to an extensive review of manufacturing and production processes for all lens-care products. It was determined that the increased rate of infection wasn't the result of contamination, but of a compounding of multiple factors. The phrase "perfect storm" has been used to describe the combination of poor compliance and decreased effectiveness of lens-care products. This raises the question of why a lens-care product would be brought to market if there were any question about its efficacy. But, this question is not so easily answered.

Lens-care products are rigorously tested to ensure they meet a minimum degree of safety and efficacy. The Food and Drug Administration (FDA) and the International Standards Organization (ISO) have set guidelines for testing the antimicrobial efficacy of lens-care products. The ISO-FDA (FDA 510(k) and ISO-14729) regimen is the standard for testing disinfection efficacy. The test organisms used to challenge the lens-care system are Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 6538, Serratia marcescens ATCC 13880, Candida albicans ATCC 10231 and Fusarium solani ATCC 36031.³ The dilemma here is that numerous strains of the various test organisms exist, yet antimicrobial effectiveness need only be demonstrated in these specific strains. Additionally, the ISO and FDA conduct tests under the manufacturer's recommended usage instructions. Although under these "normal" conditions, efficacy generally surpasses the required minimum pass criteria, contact lens wearers often don't live under or adhere to these conditions in daily life.⁴

All lens-care system regimens consist of three primary steps: cleaning, rinsing and disinfecting. Eyecare practitioners and the contact-lens wearing public easily embraced the no-rub lens-care system for its convenience. The advantage of a stand-alone test for antimicrobial effectiveness with this type of solution was that a lens-care product could demonstrate efficacy at disinfecting lenses without the added rubbing usually involved in cleaning contact lenses. Unfortunately, along with the no-rub regimen, two patient habits have emerged. First, many patients interpreted "no-rub" to also mean "no-rinse." Without reading the new instructions, some patients opted to remove their lenses and, without rinsing them, place them directly in a case filled with solution — thus bypassing not only the rubbing step but also the rinse step. We all recognize that some patients don't regularly or consistently rub and rinse their lenses. But, we may have overlooked or underestimated the effects of the second misuse. The second patient habit that has emerged since the advent of no-rub solutions is the propensity to "top off" solution instead of completely discarding used solution, cleaning the lens case and letting it air dry before adding fresh solution. This creates a moist environment with a decreasing concentration of disinfecting solution and a high likelihood of biofilm production.

This Strategic Skill Builders Continuing Education article is made possible by a grant from CIBA Vision. The content is independently produced by Optometric Management. Please submit your answer card by February 15, 2009.

SOLUTION COMPONENTS

Multipurpose solutions have simplified the number of components needed to accomplish the three tasks of a proper lens-care regimen. The goal is to find a compound that is an effective cleaning agent, yet is gentle enough to come in direct contact with the eyes. The search for an ideal disinfectant has led to the development of some unique chemical compounding with buffers and lubricants. Some of the recently marketed multipurpose solutions had an added emollient to improve the comfort level of the lens-care products. Researchers have speculated that these wetting agents may have diminished the effectiveness of the solutions' disinfectants when compounded with the practice of "topping off."

Clinicians speculated that in the chronically moist environment of the contact-lens case interior, a biofilm developed. The chemical nature of the wetting compound would then provide "food" for an organism introduced from the outside environment. Also, in the scenario in which fresh solution is added to previously used solution, the full concentration of the lens-care system is unavailable and cannot provide maximum disinfection.⁵

For these reasons, it's important to explain to patients why they must discard used solution, then clean and dry the lens case before adding fresh solution. Additionally, be sure to recommend frequent replacement of lens cases. (The American Optometric Association recommends patients change their lens case every one to three months.) Third, remind your patients of the evaporative effect that occurs when they leave filled lens cases and/or bottles open. Let patients know that this effect changes the concentration of the lens-care system and may reduce biocidal efficacy.

LENS CARE COMPATIBILITY

Related to the debates about the impact of microbiology on the safety of contact-lens wear is a continuing discussion on the effects of contact-lens solutions and corneal staining. As contact-lens fitters, we assume that if a patient has a significant amount of staining, then he or she will be symptomatic, or we would be able to see the staining under white light. Neither of these assumptions is necessarily correct. How often do we apply fluorescein for a follow-up evaluation to our patients who wear soft contact lenses? Ideally, we should do so regularly, just as we perform lid eversion routinely. We can't find a problem if we don't specifically look for one. Researchers have proven that discomfort and increased corneal staining are correlated.⁶ Additionally, current discussion focuses on the potential for lens material incompatibility with certain lens-care product preservatives. Researchers have demonstrated that cleaning certain silicone-hydrogel lenses with polyhexamethylene biguanide hydrochloride (PHMB)–preserved lens care systems is associated with corneal staining.

Controversy surrounds the extent of the relationship between corneal staining and preservative incompatibility.⁷ It's important to know that all biguanides aren't the same, and that each lens-care system uses a variety of biguanide compounds. Yet clinical significance still exists, and as contact-lens fitters, we need to stain the cornea and look for any contact-lens solution–associated ocular-surface disruption. Keep in mind that all preservatives have the potential to create a toxic or allergic response. Hydrogen-peroxide systems are often touted as an ideal lens-care system that helps users avoid a solution-preservative response; however, they aren't without their own compliance complications, including a skipped or incomplete neutralizing step, use of an old case with an inactive neutralizing disc, saline use instead of peroxide, and so on.

Published reports have also examined the time frame in which it is possible to see corneal staining related to contact-lens wear.⁸ It's not realistic to expect all contact-lens patients to come to your office for an examination within one to two strategic skill builders hours after they apply their lenses, but keep this time frame in mind when you see no staining during your examination.

It's important to emphasize the systematic components of lens-care products. All systems require the three steps mentioned: cleaning, rinsing and disinfecting. With multipurpose systems, patients may complete these steps using just one bottle of solution; others may require multiple bottles of lens-care products. Table 1 summarizes some of the more popular lens-care systems available today. Included in the table is the enzymatic regimen, which we often omit because most of today's contact lenses are disposable. It's prudent, however, to discuss this regimen with contact-lens patients, because some might seek their own methods of remedying contact-lens discomfort.

OFFER LENS "CARE"

Most eyecare practitioners delegate the responsibility of teaching proper lens care to staff members, or we assume that each patient will thoroughly read the package inserts of their lens-care products for lens-care instruction. But, if we don't have the time to keep current on ever-changing lens-care regimens, is it realistic to expect this of our staff members or patients? Many ECPs cringed at the introduction of no-rub lens-care products, yet how many of us discussed this issue with our patients and explained why we recommend rubbing as part of the lens-care regimen? And, how many of us explained that a steady stream of rinse solution is still necessary in lieu of rubbing? To make a comparison: To receive the cleaning effectiveness of rubbing with a no-rub system, one would have to apply the steady stream of rinse solution with a force analogous to that of taking a shower with a fire hose.

Many practitioners and staff members become indignant at the idea that patients top off their solution, or are outraged when a patient brings his or her lenses in a case smudged with black, fuzzy marks. We assume that it's common sense that a patient won't reuse lens solutions and will rinse and dry his or her lens case and replace it regularly. After all, patients don't save their mouthwash for reuse. We assume that our patients understand proper lens care. But we should not make this assumption. With a few simple steps, you can improve patient compliance and understanding of the importance of lens care.

The number of lens-care products available is overwhelming, so the potential for incompatibility between lens materials and lens-care products certainly exists. It's just as important to specifically prescribe a lens-care regimen when you choose a patient's lens material and parameters. We need to emphasize that, as part of the lens-care system, one should not mix and match products, and we must make clear why buying less expensive, and unknown, generic alternatives may be risky. Educate your patient as to why you have prescribed a particular lens-care system, and encourage him or her to contact your office before making any additions or changes to the regimen. This specific education may reduce the tendency for patients to view lens-care systems merely as a purchase, and they are likely to better understand the importance of this part of their eyecare regimen. Even if you prescribe a peroxide lens-care system, be sure to review with the patient what potential mistakes can be made and how to avoid them.

Today's contact-lens wearer is far more savvy about options in lens materials and lens-care products. Regrettably, that doesn't equate to being more knowledgeable. We must educate our patients about why we prescribe a particular lens and lens care product for their needs. Some manufacturers have created patient-care Web sites from which we can electronically send patient information, lens-care instruction and reminders to replace lenses and lens cases. Eyecare providers must supply continual education to our patients. Don't assume that a patient who has worn contact lenses for years necessarily has current knowledge and understanding of lens care. That information may need some refreshing.

THE NEED FOR EYEWEAR

Additionally, don't overlook a patient's need for glasses. Even the most adherent contact-lens patient still needs eyewear. Explain to your patients that they shouldn't wear contact lenses while they are ill. Inform them that they should discontinue lens wear if their eyes are red or if they have discharge or discomfort. A good rule of thumb is to determine whether one's eyes look good, feel good, and see well before applying contact lenses. Clear and concise communication shows your concern as an eyecare provider. Encourage patients to ask questions, and tell them that if you don't know the answer, you'll find out and let them know — and then follow through. OM

OM will furnish references upon request.