Color changing contact lens to monitor eye treatment

According to new research, a colour-changing contact lens shall monitor eye disease treatment in future.

As of now eye drops and ointments have one major drawback which is that it's hard to tell how much of the medication is actually getting to the eye. The scientists have developed a contact lens that changes colour as drugs are released and this visual indicator could help eye doctors and patients readily determine whether these medications are where they should be. The study has appeared in ACS Applied Materials & Interfaces.

Studies suggest that less than 5 per cent of drugs in eye drops and ointments are absorbed, and much of the absorbed medication ends up in the bloodstream instead of the eye, causing side effects. Eyes are adept at keeping foreign objects out. When something ventures into or toward an eye, the lids blink and tears start rapidly flowing to avoid infection and damage from it. These processes though helpful can hinder the uptake of much-needed medications. Contact lenses may be a more effective way to deliver drugs directly to the eye, but real-time monitoring of drug release is still a challenge.

To meet this challenge, Dr Dawei Deng and Zhouying Xie sought to create a drug-delivering contact lens that would change color as the medication is released into the eye. The researchers fabricated a color-sensitive contact lens using molecular imprinting, a technique that creates molecular cavities in a polymer structure that match the size and shape of a specific compound, such as a medicine.

In the study, the molecularly imprinted contact lenses were loaded with timolol, a drug used to treat glaucoma. Then, the team exposed the lenses to a solution of artificial tears, which was used as a stand-in for the eye. As the drug was released from the contacts, the architecture of the molecules near the drug changed, which also changed the color in the iris area of the lenses. No dye was involved in the process, reducing possible side effects. The researchers could see this shift with the naked eye and with a fiber optic spectrometer. They conclude this new lens could control and indicate the sustained release of many ophthalmic drugs.