Contact lenses as a platform for ocular drug delivery

Introduction: Most ophthalmic drugs are delivered through eye drops even though only about 1 - 5% of the drug reaches the target tissue and the patient compliance is not good. Drug-eluting contact lenses could significantly increase bioavailability, reduce side effects and improve patient compliance. Areas covered: Recent research on drug-eluting contact lenses has focused on increasing the release duration through molecular imprinting, dispersion of barriers or nanoparticles, increasing drug binding to the polymer, sandwiching a PLGA (poly[lactic-co-glycolic acid]) layer in a lens and developing novel materials. This review covers all these studies with a specific focus on the transport mechanisms and advantages and disadvantages of each approach. Expert opinion: The main reason for prior failures was the short duration of release from the lenses. The new technologies can provide extended drug release for hours to days. The in vivo animal and clinical studies have proven the safety and efficacy of drug-eluting contact lenses, while showing considerable improvements compared to eye drops. The future appears to be promising but several challenges remain such as processing and storage issues, regulatory hurdles, high costs of clinical studies, potential lack of acceptance by the elderly, etc.