Reader and Industry Forum
Reader and Industry Forum
Countering Noncompliance With Lens Care and Case Technology
By Brad Hall, BSc, & Lyndon Jones, PhD, FCOPTOM, FAAO
Contact lens storage cases are a critical factor in contact lens success, but patients frequently regard them as unimportant to safe contact lens wear. Many studies have shown that contact lens cases are notorious for harboring microorganisms that can lead to microbial keratitis (MK) (Gray et al, 1995; Wu et al, 2010; full list at www.clspectrum.com). The risk for developing MK from contaminated contact lens cases is further increased when contact lens wearers are noncompliant with appropriate case cleaning (Collins and Carney, 1986; Yung et al, 2007) or case replacement (Sweeney et al, 2009; Dumbleton et al, 2010). Recent reports have shown that frequent contact lens case replacement reduces case contamination (Lakkis et al, 2009; Wu et al, 2010).
Many patients are also noncompliant with replacement of their contact lenses. Recent studies have shown that approximately one-third of silicone hydrogel lens wearers using frequent replacement lenses fail to replace their contact lenses when scheduled (Dumbleton et al, 2010).
In an attempt to address these specific issues, a number of novel and existing contact lens storage cases and an existing lens cleaning system have been marketed to increase compliance, aid with lens cleaning, and/or resist lens case contamination.
Count-it (Count-it, Inc., www.count-it.net) (Figure 1) is a new contact lens case designed to track how many times contact lens wearers have worn their lenses. The counter is located on the top of the lens case and counts from zero to 14 to mimic a typical two-week replacement schedule.
Figure 1. Count-it Contact Lens Case.
LensAlert (Watchdog Group, LLC, www.lensalert.com) (Figure 2) is a product that is designed to enhance compliance with both contact lens replacement and lens case replacement by keeping track of when contact lens wearers should replace both their lenses and their lens case. Cases are placed in the Lens-Alert holder, and a digital countdown timer for contact lens case replacement can be set for one, two, or three months. A reminder for contact lens replacement can be set at two or four weeks.
Figure 2. LensAlert case holder.
Prevention of Microbial Contamination
Bacterial biofilms are known to form on case walls (McKenney and Ajello, 1991; Farber et al, 1995) and have been found in cases of patients diagnosed with MK (Wilson et al, 1990; Stapleton et al, 2008; full list at www.clspectrum.com). Silver is used extensively in biomaterials to help prevent microbial contamination (Gosheger et al, 2004; Crespo-Biel et al, 2009; full list at www.clspectrum.com). Ciba Vision distributes the Pro-Guard (called MicroBlock in some markets) contact lens case with its Aquify multipurpose solution. Silver is incorporated into the case plastic and has been shown to decrease bacterial contamination of the contact lens case (Amos, 2005; Amos, 2006). The Pro-Guard lens case should not be used by patients who are allergic to silver or other metals.
Farber and colleagues (1995) investigated using sodium salicylate, a nonsteroidal anti-inflammatory drug, to prevent biofilm formation in contact lens cases and found that varying the concentration of sodium salicylate could reduce biofilm formation by 39 to 95 percent.
Wu et al (2010) recently demonstrated that bacterial contamination in standard “two well” contact lens cases is higher on the upper inner rim compared to the lower inner base while for stand-up cases (used for peroxide-based regimens), higher numbers of microorganisms accumulate on the contact lens basket compared to the upper hinge. To-date, no strategies have been proposed to reduce contamination on the baskets of peroxide-based contact lens cases.
In addition to microbial contamination issues, lens cases may play a role in enhancing contact lens cleaning. Clinical observations have suggested that rubbing lenses prior to overnight soaking assists with deposit removal (Nichols, 2006; Cho et al, 2009). A new lens case concept emerging on the market, devised by a University of Waterloo engineer (Dave Zakutin, BaSc), periodically agitates the lens case overnight to obtain the cleaning benefits of rubbing the lens without the need to do so. The device, marketed under the trade name “Jitterbug” (www.protein-eraser.com), initially pulses for 16 seconds, then pulses once every 15 minutes thereafter for six hours. Preliminary studies (Joyce and Jones, 2009) have shown the device to be successful in removing protein from group IV lenses. This device also incorporates a timer to track lens replacement (Figure 3).
Figure 3. Jitterbug vibrating lens case.
Novelens (Novelens, Inc., www.novelens.com) (Figure 4) is a novel contact lens storage case that the company says keeps lens deposits that have “soaked” from the lenses separate from where lenses are stored during the disinfection process. The device has two chambers built into each contact lens well. Holes in the bottom of the first chamber lead to the lower second chamber, which stores lens solution used to initially rinse the lenses as well as any removed deposits. The two chambers are kept separate during lens storage to keep removed deposits away from the lenses, according to Novelens.
Figure 4. Novelens lens case.
The PuriLens System (The LifeStyle Company, www.purilens.com) (Figure 5) is designed to clean and disinfect contact lenses without the use of conventional contact lens solutions (Choate et al, 2000; Gromacki, 2004). Contact lenses are placed in a basket and then left in the machine for 15 minutes of automatic cleaning before the machine shuts off. It uses a magnetic pedal on a flexible arm to agitate the saline solution and loosen deposits from the lenses. A UV light (253.7 nm) is used to disinfect the lenses, case, and saline solution (Choate et al, 2000; Gromacki, 2004). A study by Choate and colleagues (2000) examined the efficacy of the PuriLens System to eliminate inoculums of microorganisms and found more than 99 percent reduction after 15 minutes of use.
Figure 5. PuriLens lens care device.
Patients' Best Interest in Mind
The development of novel contact lens storage cases will continue in an attempt to aid with patient compliance, safety, and lens comfort. However, their value in reducing serious complications such as MK remains unproven at this time. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #181.
Brad Hall is a PhD candidate in Vision Science and Biology at the University of Waterloo, Waterloo, Ontario, Canada. Dr. Jones is associate director of the Centre for Contact Lens Research and a professor at the School of Optometry at the University of Waterloo. He has received research funding from Alcon, AMO, B+L, Ciba Vision, CooperVision, Johnson & Johnson, and Menicon.
Contact Lens Spectrum, Issue: December 2010