Drug-Loaded Contact Lenses For Treating Eye Diseases
Date: 31-Dec-2004
Most people use eye drops to relieve discomfort or treat various eye diseases. However, 95% of eye drop medication can be ineffective, as the eye drops mix with tears and drain into the nasal canal. This can then cause negative side effects. Researchers at the Institute of Bioengineering and Nanotechnology (IBN) have solved this problem by developing polymeric contact lens material that can be loaded with eye medication.
Using an in situ micro-emulsion polymerization process, Dr. Edwin Chow and Dr. Yang Yi-Yan were able to incorporate drugs within a nanostructured polymer matrix. To do this, they used a bi-continuous micro-emulsion as a medium to prepare the drug-loaded contact lens material. This material is ideal for biological and biomedical applications, as it is compatible with human skin cells and corneal epithelial cells, and is also permeable to gases, water and components of the tear fluid.
“This process involves combining oil-based monomers, water and a polymerizable surfactant,” said Dr. Chow, lead scientist for this research project. “The surfactant binds the monomers and water to create a clear mixture. A specific dose of drugs is added and the combined mixture is then poured into a lens mold. When this mixture is hard, the resulting lens is full of tiny nanometre-sized channels. This cross-polymerization of organic components in a bicontinuous micro-emulsion can be initiated readily using either heat or UV light. Using this simple process, one can easily fabricate transparent and mechanically strong contact lens material in the form of sheets or ophthalmic molds.”
Dr Edwin Chow, Lead Scientist For Drug-Loaded Contact Lenses Project
Dr. Chow and Dr. Yang’s lenses are made in a novel one-step process, allowing the polymer network to be fabricated easily and cost-effectively. Another advantage of using these contact lenses over other ophthalmic drug delivery systems is that the drug delivery rate can be controlled and remains effective over longer periods of time.
“The drugs ‘sit’ in the structure of the material and are released into tiny channels, from which they leak onto the eye surface. We can control the flow of the drugs by varying the width of the channels. This can be done by changing the constitution of the mixture that makes up the lens material,” said Dr. Chow.
IBN is currently looking for partners to commercialize the lens materials and they have already received enquiries from several contact lens companies. The technology could be used to deliver medication for a range of eye diseases, including glaucoma, which is currently difficult to treat.
“Our technology allows different types of eye medication to be incorporated into the lens’ mixture,” said Dr. Chow. “We are able to increase the drug-loading capacity without affecting the properties and clarity of the lens. In addition to glaucoma medication, we can load antibiotic or anti-inflammatory drugs. This material could also be modified to produce self-lubricating contact lenses to relieve the discomfort of contact lens wearers suffering from dry eyes. Other potential applications include loading wound-healing drugs in the lenses to treat corneal wounds, or to fabricate the lens material for use in vision correction.”
Moving ahead, the researchers are now conducting in vivo animal studies, in order to understand the detailed pharmacokinetics of drug release with their lenses.
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