Scientists in Singapore have developed a contact lens that they say delivers precise amounts of medication.

Topical drops can have an all-to-brief time of effect on the eye and can filter into the body to cause systemic side effects, says scientists at the Institute of Bioengineering and Nanotechnology (IBN) in Singapore.

To that end, the IBN scientists developed a simple method of making a new polymeric lens material. The medication is added directly into the material that eventually becomes the lens. The drug is polymerized into the structure of the lens material and is released from the matrix into channels to slowly filter onto the eye surface.

The lens material can be tailored to dispense different drugs and remain effective for extended periods, says co-inventor Edwin Chow.

"Drugs may be encapsulated in polymeric nanoparticles, which are then dispersed in the lens material," he says. "By altering the size, concentration and structure of these polymeric nanoparticles, we can further control the drug delivery rate, while retaining the appropraite lens clarity."

Two potential uses: glaucoma and contact lens-related dry eye. The inventors point out that glaucoma is difficult to treat and existing medications have unwanted side effects. Meanwhile, contact lens wearers who suffer from dry eye could benefit from a drug-dispensing lens that is self-lubricating.