contact lens care and compliance
Nature May Be the Key to Healthier Contact Lens Wear
BY SUSAN J. GROMACKI, OD, MS, FAAO
Years ago, a professor told me, “The best defense against microbial eye infection is the eye itself.” After an initial moment of disbelief, it made sense. Of course, nature could do it better. With man-made products, bioincompatibility and tissue toxicity are often directly proportional to disinfection efficacy. When attempts are made to preserve the ocular tissue, diminished efficacy often results.
Science is looking back to nature to solve medical problems and enhance human life. Various bio-inspired products use natural ingredients or mimic actions that occur in nature. Initially, this technology was developed to solve issues, such as the aforementioned chemical toxicity. These products also have been designed to improve the efficiency of certain tasks. Ideas that have come to market include bacterial control inspired by red algae and barberry; wound healing inspired by flies; and water purification inspired by the marsh ecosystem.
What about contact lens care? The lotus plant serves as an interesting example. This plant possesses some of the most water-repellent leaves in nature. You might expect the leaves to have a smooth surface, but the leaves are actually rough. The nooks on the leaf's surface trap air. Water droplets float on that air. Then, any movement of the leaf (from wind, wildlife, and so on) causes the water to roll off taking dirt particles with it. One application is a fabric called GreenShield, which mimics the lotus effect, rendering itself as water- and stain-repellent as conventional fabric, while utilizing 8 times fewer fluorinated chemicals. So, could intentional lens deposition (Figure 1) prevent further lens deposition?
Figure 1. Could lipid deposition on a contact lens surface actually be beneficial to eye health?
Next, let's go in a different direction and intentionally place a polar lipid onto a contact lens surface. This might allow the aqueous tears to interface better with the contact lens, rendering the lens more wettable.
Perhaps we could place a natural antimicrobial agent onto a contact lens surface to prevent the formation of biofilms, and as a result, microbial infection. Examples include derivatives of cloves, oregano, thyme, paprika, and yes, lysozyme itself. Originating from our own tears, lysozyme is a natural antimicrobial peptide. Its attachment to lenses (some more than others) is well known. Could we somehow engineer this to be beneficial?
Too much, however, of this denatured protein creates decreased lens comfort and increased inflammatory responses, such as giant papillary conjunctivitis. Additionally, the human eye produces several antimicrobial peptides called defensins, which have become a recent topic of interest in therapeutics research because they have a broad spectrum of antimicrobial activity (against bacteria, fungi and viruses) and they can accelerate epithelial healing.
Future, bio-inspired technology will be homeostatic; that is, it will help people maintain or augment their own bodily system functions. Of course, there are many more questions than answers at the moment. But it is when this type of out-of-the box thinking occurs that true innovation happens. CLS
For references, please visit www.clspectrum.com/references.asp and click on document SE2010.
Dr. Gromacki is a Diplomate in the Cornea, Contact Lenses, and Refractive Technologies section of the American Academy of Optometry. She is Chief Research Optometrist at Keller Community Hospital in West Point, New York.