Innovative ocular drug delivery systems: A comprehensive review of nano formulations and future directions

The eye's intricate structure and blood-ocular barriers pose significant challenges to effective ocular drug delivery. The blood-retinal barrier and blood-aqueous barrier restrict drug penetration, leading to poor bioavailability and limited treatment options for ocular diseases. Various administration routes, including systemic, topical, intravitreal, subconjunctival, and intracameral, have been explored to overcome these barriers. Nanotechnology-based platforms, such as liposomes, nanoemulsions, nanomicelles, nanosuspensions, and niosomes, have shown promise in enhancing ocular drug delivery. These platforms offer improved solubility, stability, and targeted release, increasing the efficacy of treatments for conditions like age-related macular degeneration, cataracts, diabetic retinopathy, fungal keratitis, and retinoblastoma. Future perspectives focus on developing minimally invasive, sustained-release systems that maintain intraocular efficacy. Nanofibers and stimuli-responsive drug delivery systems also hold potential for overcoming ocular delivery challenges.