The eye-contact patch for ocular drug delivery is equipped with an array of self-implantable micro-drug-reservoirs. Source: NTU Singapore

Current methods for treating eye diseases, such as glaucoma and macular degeneration, rely on eye drops and ointments, but their efficacy is hindered by the eye’s natural defenses -- blinking and tears. Eye injections can be painful and increase the risk of infection and eye damage.

An eye patch bristling with drug-delivering microneedles is under development as a more effective localized therapy for chronic conditions. The proof-of-concept patch, successfully tested by Nanyang Technological University, Singapore (NTU Singapore) scientists in mice, is covered with biodegradable microneedles that deliver drugs into the eye in a controlled release. The patch is gently pressed onto the eye’s surface, much like putting on contact lenses, after which the drug-containing microneedles detach by themselves and remain in the cornea as drugs are released over time as they dissolve.

When tested on mice with corneal vascularization, a single application of the patch was 90% more effective in alleviating the condition relative to application of a single eye drop with 10 times more drug content. No puncture was observed on the cornea after a week, suggesting that the microneedles are strong enough to penetrate the cornea but not too stiff to spear through the whole cornea.

The 2 mm x 2 mm flexible polymeric eye patch includes nine microneedles of pyramidal shape for optimal tissue penetration. Each needle is composed of hyaluronic acid, a substance found in the eye and used often in eye drops, and is thinner than a strand of hair. A modified version of the hyaluronic acid is added to form a second layer of the needle to slow down its degradation rate and ensure a slower release of the drug.

The research is published in Nature Communications.