Biosignal looks into antibacterial coatings on contact lenses

Biosignal and the Australian Institute for Eye Research have completed technical development of a method of attaching antibacterial compounds to the surfaces of contact lenses.

Contact lenses on world markets do not have antibacterial coatings as no technologies to date have been effective and safe for the eye. After months of laboratory development, the extended wear lenses—lenses worn for about a month at a time—will now proceed to an animal safety study and overnight human testing.

Biosignal reported in March that it would produce further batches of lenses to confirm activity, wettability and cytotoxicity. This work has now been successfully completed and a lens combination that consistently meets the required levels of activity, wettability and in vitro safety has been developed.

The next stage of development is in animal safety studies where lenses are worn by the animals. The study, based on standard safety protocols for testing contact lenses, will be used to measure any possible adverse effects to the eye caused by exposure to the antibacterial lens. If no adverse effects are observed the lens will proceed to a human clinical study.

Clinical studies will begin with an overnight trial in 10 patients measuring adverse responses. If there are no adverse responses a 30-patient 6-month extended wear trial will be conducted to monitor responses to extended wear of the lenses and to measure post wear antibacterial efficacy. If initial indications from this trial are positive then a 250 patient study looking at reduction of adverse responses associated with lens wear will be commenced.

“Effective and non-toxic antibacterial lenses will provide a strong point of difference in the highly com-petitive $US5bn annual contact lens market,” said Michael Oredsson, managing director of Biosignal.

“Hygiene for existing contact lens wearers depends on a certain amount of diligence by wearers. However, even if a wearer is diligent about hygiene, this doesn’t guarantee avoidance of eye infections,” he added.

The extended wear development project is supported by a START grant from AusIndustry. Results from the animal safety study and the initial human overnight study are expected by the end of June.

Biosignal listed on the ASX in April 2004 to commercialise a novel antibacterial technology. The first application is reducing risks of infection from contact lenses.

Biosignal’s antibiofilm technology is based on a discovery that the eastern Australian seaweed Delisea pulchra produces natural furanones that disable bacteria's ability to colonise. Bacteria rapidly produce resistant strains when faced with strong selective pressure by killing agents or growth-inhibitory agents. Biosignal’s anti-biofilm technology lulls bacteria to inaction and appears to avoid the problem of bacterial resistance.

Biosignal produces synthetic compounds effective on inanimate surfaces such as pipes, membranes and medical devices; and animate surfaces such as lungs, skin and teeth.