SOLUTIONS

Contact Lens Solutions and Lens Care Update

A rapid evolution of contact lens care has taken place during the past year. Most changes are an expansion of claims and new evidence about how previous products may be used. However, you need to understand a few new product modifications and even a few new products as well. In addition, Consulting Editor Randy McLaughlin, OD, MS, provides a comparison of lens care regimens (see Chemical Disinfection Update).

The Rub

Optimal contact lens care involves clean hands, a clean contact lens case, rubbing the lens with cleaner or a multi-purpose solution, rinsing that lens and placing it into fresh solution for storage (with or without an enzyme for added cleaning). One major change in the inevitable evolution to the dream system requiring only lens removal and placement into a clean case with fresh solution (no rub or rinse) is the recent indication for no rub for several multi-purpose solutions.

What's In a Label ­ MPS, MPDS, "No Rub Needed"

Some practitioners dismiss such labeling distinctions as marketing gimmicks. Others object to manufacturers contradicting their instruction to patients. In truth, these product descriptors mean different microbiological and cleaning efficacy tests recommended by the FDA have been passed. Such indications mean additional levels of protection have been confirmed beyond what was proven before for initial approval. Product labeling can give eyecare professionals useful information. Based on the results of these tests, manufacturers are allowed to label their products as:

• Multi-purpose solutions (MPS)
• Multi-purpose disinfecting solutions (MPDS)
• No Rub Required

See Table 1 for FDA solution status based on published product labeling.

Multi-purpose Solutions (MPS) ­ Need That Regimen

ReNu (Bausch & Lomb), SoloCare (CIBA Vision) and Opti-One (Alcon) are labeled as multi-purpose solutions. During the "Stand Alone" Test (soaking only), the solution must kill one log unit each of three test bacteria and a total of five logs among the three. The solution must also show no growth of two test fungi during the labeled soak time. When all regimen steps are followed (rub, rinse, soak), the product must kill or remove five logs of each test organism. (Hence the name "Regimen Test.") The product must also prove substantial similarity relative to cleaning and to other marketed MPS products in a clinical trial.

New RGP solution from Alcon

Multi-purpose Disinfecting Solutions (MPDS) ­ Kills with No Rub or Rinse

Opti-Free Express (Alcon) and ReNu MultiPlus (Bausch & Lomb) are the only two products that have achieved the distinction of "MPDS," and they kill with no rub or rinse. This is in vitro, however, and they are not recommended for use in this fashion. These solutions achieve a higher microbiology challenge than the multi-purpose solution in "stand alone" (soaking only) testing. If the solution passes this test, it is presumed to pass the five-log regimen test. The product must kill at least three logs of each of three test bacteria and one log of each of two test fungi during their labeled soak times without a rub or rinse step. The MPDS designation does not address cleaning efficacy differently than MPS solutions.

	CIBA Vision updates peroxide care to one-bottle system.

No-Rub Required Solutions

Three products now have "No-Rub Needed" directions for use: Alcon's No-Rub Opti-Free Express MPDS, which is cleared for all lens wearing schedules, Allergan's Complete, which recently received clearance for lenses worn up to 30 days, and CIBA's new AO Sept Clear Care, also approved for no-rub for lenses used up to 30 days. For this claim, the product must demonstrate microbiology and cleaning efficacy without a rubbing step. Alcon achieved the first "no-rub required" labeling for Opti-Free Express MPDS by demonstrating certain levels of disinfecting and cleaning efficacy. In order for a contact lens care product to obtain no-rub labeling, the product must provide the following evidence:

• Achieve MPDS labeling by meeting stand alone (no rub or rinse) criteria as above.
• Kill/remove five logs of each of five test organisms with rinse and soak regimen only (no rubbing).
• Prove that microbiological activity is not significantly impacted when artificial soil is added to the test (to simulate dirty lenses).
• Demonstrate cleaning.

For example, Opti-Free Express, must prove in laboratory studies that each of the three components (citrate, Tetronic 1304 surfactant and AMP-95) in the formulation provide cleaning activity such that Tetronic provides the surfactant action, Citrate removes protein from the lens during the soak and AMP-95 helps prevent protein build-up while the lens is worn, according to Alcon.

Alcon claims Opti-Free Express provides cleaner lenses, as measured objectively by High Performance Liquid Chromatography, in a clinical study than a control of a marketed solution used with a rub. The same pair of lenses was worn for 90 days. These results allowed the FDA to clear No-Rub Opti-Free Express for all lens wearing schedules.

Many practitioners appreciate the margin of safety in new approvals for products providing adequate disinfection without the rub for their non-compliant patients (most patients, most of the time). Yet some practitioners object to advertising and labeling of products which emphasize the "no rub." Many practitioners continue to instruct patients or have their staff recommend rubbing to remove lens debris. Others are less concerned with rubbing because patients should dispose their lenses on a two-week cycle. However, recent evidence suggests that compliance with lens replacement cycles is decreasing, and only 50 percent of patients actually rub their lenses. Fortunately, both Alcon and B&L have published data during the past year demonstrating antimicrobial effectiveness against Pseudomonas and other organisms for Opti-Free Express and ReNu MultiPlus, not only for the bacteria they are required to test against by FDA, but also for isolates from clinical ulcers.

New Products

	Superficial but extensive corneal staining secondary to multi-purpose solution use.

• Alcon's Clerz Plus Lens Drops contain Clens 100, a patented surfactant. Clens 100 has a surface-active behavior and micelle-forming ability which contribute to cleaning, wetting, emulsifying and dispersing activities in care products. It has only mild effects on ocular tissue compared to other, more aggressive surfactants. Clens 100 is selected to act on a variety of lens contaminants, including protein, lipid and calcium deposits, especially the protein lysozyme, a significant contaminant of FDA Group IV (ionic, high-water content) hydrogel lenses. Because Clens 100 is a weak anionic (negatively-charged) compound, it can interact with cationic (positively-charged) lysozyme through electrostatic (ionic) bonding. This interaction can be reinforced through hydrophobic associations between Clens 100 and hydrophobic regions in the protein's structure. The second surfactant in Clerz Plus is Tetronic 1304, which provides cleaning action mainly through hydrophobic and hydrogen-bonding interactions. This product is recommended by practitioners as an eyedrop for improved comfort during lens wear and is a first attempt at on-the-eye cleaning.
• With Unique pH Multi-purpose RGP Solution, Alcon is aggressively entering the rigid gas permeable solutions market which has been dominated by Bausch & Lomb/Polymer Technology Corp. with its Boston RGP lens care products. Alcon claims its Unique pH provides individualized comfort for the RGP lens wearer based on his or her own ocular environment. Unique pH contains a polymer system, HP Guar, that changes solution characteristics as a function of pH. At a pH of 7, the product dispenses as a low viscosity solution to facilitate cleaning and handling during lens care. Upon exposure to tears at a slightly higher pH (average 7.3), the solution increases its viscosity. The thicker solution in the eye may result in more comfortable lens wear without blurry vision. 
  The surfactant in Unique pH is Tetronic 1304, also found Opti-Free Express and Clerz Plus lens drops. Based on its structural features, Tetronic provides cleaning action mainly through hydrophobic and hydrogen-bonding interactions with deposits and other debris on contact lenses. Unique pH also contains 0.00011% Polyquad as the preservative.
• Allergan's Complete is now in a new space-age design bottle (with no surrounding box for environmental friendliness) with a snap-on container on the bottom for a lens case. More importantly, it contains hydroxyproply methylcellulose, a proven wetting and humectant agent. The HPMC (called Pro-Tec Shield) allows Allergan to claim that its timed release as well as moisturizing and coating properties allow for longer lasting, later day comfort.
• Refresh Contacts eyedrops from Allergan contains carboxymethylcellulose (CMC), a mucomimetic with mucoadhesive forces which coats the lens for lasting comfort. Its Purite preservative system contains no chemicals and is buffered with naturally-occurring and naturally-eliminated lactate. It is the same formulation as Allergan's popular dry eye product Refresh Tears. 
  According to a patent issued in 1999, the CMC in Complete and Refresh Contacts makes them cytoprotective. The products' polyanionic properties may reduce low-grade signs (such as staining reported with some MPS solutions) and symptoms (also reported with some MPS solutions) when the solution containing it is used to insert contact lenses. This option may complement or replace the common practice of using a non-preserved or mild preservative saline rinse prior to lens insertion to avoid irritation by some MPS solutions.
• CIBA Vision's AO Sept Clear Care is a cleaning and disinfecting solution, a one-bottle, no-rub lens care system formulated with a built-in cleaner specifically designed to clean lenses and remove protein. The cleaning activity results from activity of Pluronic. Clear Care combines one-bottle convenience with peroxide disinfection.
• CIBA has also introduced in international markets Solocare Plus, a no-rub MPS that contains AquaLub. AquaLub promotes contact lens moisture retention and prevents protein deposits and improves late day comfort, according to CIBA Vision.

Recent data reported by numerous authors has pointed to toxicity from MPS and MPDS solutions, both in vivo and in vitro. Some of these reports suggest such toxicity is not observed with AO Sept and may be prevented by some of the aforementioned protective mechanisms.

What's Next?

Contact lens care products have come a long way since the early days of heat disinfection with salt tablets. Yet, heat disinfection may be making a comeback (see www.eartheyes.cc) when used with sterile, non-preserved saline. UV light is a good disinfectant when used with non-preserved saline in Purilens. One-bottle lens contact lens care will continue to dominate the field. Such products will be refined and optimized. The use of solutions overall has leveled off due to slow growth of daily disposable contact lenses and expected increased use of extended wear lenses. But one-bottle lens care and on-the-eye lens wear enhancers ­ improved eyedrops for contact lenses ­ will evolve and expand in use.

Dr. Barr is editor of Contact Lens Spectrum and assistant dean of Clinical Affairs at The Ohio State University College of Optometry.