Ocusesrt-Based Ocular Drug Delivery Systems: Advancements, Challenges, and Future Perspectives

Ocular drug delivery remains a challenging area due to the eye’s protective barriers, rapid tear turnover, and limited corneal permeability, which significantly reduce the bioavailability of conventional ophthalmic formulations such as eye drops and ointments. Ocusert-based ocular drug delivery systems were developed as a controlled and sustained release approach to overcome these limitations by maintaining consistent therapeutic drug levels in the ocular tissues for extended periods. Ocuserts are sterile, thin, flexible ocular inserts designed to be placed in the conjunctival sac, where they release the drug at a predetermined rate through diffusion-controlled mechanisms. The first marketed ocusert system demonstrated improved therapeutic efficacy and reduced dosing frequency; however, issues related to patient comfort, retention, and commercialization restricted its widespread adoption. In recent years, advancements in polymer science, biodegradable materials, and formulation technologies have renewed interest in ocusert-inspired ocular inserts. This review provides a comprehensive overview of ocusert-based ocular drug delivery systems, including their design principles, materials used, formulation techniques, evaluation parameters, advantages, limitations, and clinical relevance. Emphasis is placed on recent research trends, polymer innovations, and future prospects aimed at improving patient compliance and therapeutic outcomes in ocular drug delivery.