Article Date: 9/1/2006

contact lens materials
When Caring for GP Lenses, the Material Matters

BY JEFF SCHAFER, OD, MS

Choosing a care system often requires considering many factors, including but not limited to lens type, wearing schedule, cost, convenience, managing deposits, preservative sensitivities and, of course, the  contact lens material. Knowing the characteristics of the material you're fitting will help when troubleshooting problems with wettability, comfort, fit or even vision.

FSA Materials

In today's lens practices, most GP lenses are manufactured from fluorosiliconeacrylate (FSA) materials. FSA materials generally offer excellent oxygen transmissibility while maintaining surface wettability. They also have decreased susceptibility to protein deposition. However, their surfaces can be more lipophilic, leading to hazy areas of non-wetting when contacted with various cosmetics, soaps, lotions and creams.

When fitting GPs manufactured with high-Dk FSA materials, recommending compatible care systems is critical to maintaining a clean, wettable surface.

Train patients on proper lens handling techniques and caution them to rinse any oils, lotions or soap from their hands before touching their lenses. Patients should avoid abrasive lens cleaning products such as Boston Original cleaner and Boston Advance cleaner (Bausch & Lomb) in high-Dk FSA materials including Menicon Z (Menicon Co., Ltd.), HDS-100 (Paragon Vision Sciences) and Boston XO (B&L) to avoid damaging the lens surface. Better alternatives for these delicate materials are Optimum by Lobob (Lobob Laboratories), Unique pH (Alcon Laboratories) and Boston Simplus (B&L).

Optimum Cleaning/Disinfecting/Storage (CDS) solution allows the lenses to soak overnight in a surfactant that dissolves lens deposits and retains a wettable surface. Patients may perform a digital rub cleaning step with the CDS solution or with a separate Extra-Strength Cleaner (ESC) for tough deposits. Optimum is preserved with benzyl alcohol, and after soaking in CDS solution, the patient must rinse the lens with saline before applying it to the eye.

Unique pH is preserved with Polyquad and contains the surfactant Tetronic 1304. It contains HP guar, also found in Systane, which allows for a low viscosity for overnight wetting, but at the pH of the tears increases in viscosity to provide cushioning and greater wetting after lens application.

Boston Simplus is also a one-bottle multipurpose product that's gentle on lens surfaces. It's preserved with chlorhexadine, PHMB and EDTA, which sometimes leads to preservative sensitivity. Simplus contains the cleaning agents PEO sorbitan monolaureate and betaine, the surfactants poloxamine and hydroxyalkylphosphate and the lubricating agents glucam-20 and HPMC.

The disadvantage of systems that don't contain an abrasive cleaner is in controlling heavy protein deposits. In these patients, I incorporate a liquid enzyme such as Boston One Step Liquid Enzyme Cleaner (B&L) or SupraClens Daily Protein Remover (Alcon). If enzyming isn't effective, then I occasionally clean the lenses with Progent (Menicon), which is an in-office, intensive protein remover for GP lenses. If heavy lipid deposits are a problem, then an in-office cleaning with Fluoro-Solve (Paragon Optical) or Boston Laboratory Cleaner (B&L) usually does the trick.

More Resources

For more information on GP materials and solutions, check out the online version of Contact Lenses & Solutions Summary at clspectrum.com or the GP Lens Institute at www.gpli.info.

Dr. Schafer is the chief of Contact Lens and Disease Services at The Ohio State University College of Optometry.



Contact Lens Spectrum, Issue: September 2006