Drug-loaded contact lenses to treat eye diseases

Oct 29 2004

When a person suffers from eye ailments today, nine times out of ten, he will be prescribed eye drops to treat his illness or relieve his discomfort.

However, 95% of the medication administered in this manner flows to where it is not needed. The drops usually mix with tears and drain into the nasal cavity, where they can flow through the blood stream to other organs and cause serious side effects. In addition, dosage through eye drops is inconsistent and difficult to regulate, as most of the drugs are released in an initial burst of concentration.

To counter these problems, researchers have been studying the use of contact lenses to deliver eye medication. One proposed method was to pre-soak the lenses in the drug solution, while another involved incorporating the drug solution in a hollow cavity made by bonding two separate pieces of lens material. However, neither of these methods proved very effective at delivering medication for extended periods of time.

Now, scientists from A*STAR’s Institute of Bioengineering and Nanotechnology (IBN), Dr Edwin Chow and Dr Yi-Yan Yang, have invented a simple method of making polymeric lens materials that can be loaded with eye medication for ophthalmic drug delivery applications. Their novel one-step process incorporates drugs within a nanostructured polymer matrix via an in situ microemulsion polymerization process. Through this method, transparent and mechanically strong lens materials with a nanostructured polymer network can be fabricated easily and cost-effectively.

According to Dr Chow, “The resulting material is compatible with human skin cells, as well as human corneal epithelial cells. It is also permeable to gases such as oxygen and carbon dioxide, water and components of the tear fluid. Thus, this material is suitable for use in biological and biomedical applications.”

“Our approach also allows great flexibility in designing controlled drug delivery vehicles that can be tailored to different drugs and remain effective for extended periods. Drugs may also be encapsulated in polymeric nanoparticles, which are then dispersed through the lens material. By altering the size, concentration and structure of these polymeric nanoparticles, we can further control the drug delivery rate, while retaining the appropriate lens clarity,” he added.

This new approach could be adapted to deliver glaucoma medication, as this eye disease is particularly hard to treat and existing medications have numerous side effects. Glaucoma accounts for 20% of blindness in Singapore, and is rapidly becoming the second major cause of blindness in Asia after cataracts. Contact lens wearers with dry eyes may also benefit from this invention, as the material can be modified to produce self-lubricating contact lenses.

This technology has been identified for Commercialization of Technology funding by A*STAR’s Exploit Technologies and IBN is looking for partners to help with its commercialization.