Introduction

Delivering drugs effectively to the posterior segment of the eye poses a significant challenge due to anatomical and physiological barriers such as the blood-retinal and scleral layers. Conventional approaches, including topical and systemic routes, often fail to achieve therapeutic drug levels in posterior ocular tissues, leading to the need for more specialized strategies.

Methods

This review examines current and emerging drug delivery methods designed to enhance posterior segment targeting. The evaluated approaches include suprachoroidal and subretinal injections, intravitreal administration, and periocular techniques such as retrobulbar and peribulbar injections. Additionally, the review considers the role of microneedle technologies, biodegradable polymers, and injectable hydrogels in enabling minimally invasive, site-specific, and sustained drug delivery.

Results

Suprachoroidal delivery has gained attention for its ability to achieve high bioavailability in chorioretinal tissues while minimizing exposure to the anterior segment and systemic side effects. Subretinal injection provides advantages for gene and cell therapies by bypassing inner ocular barriers and directly targeting the retinal pigment epithelium and photoreceptors. Intravitreal injection remains widely used but carries risks such as infection, hemorrhage, and retinal detachment. Retrobulbar and peribulbar injections continue to serve as effective routes for anesthesia and drug delivery in selected clinical contexts. Collectively, these emerging systems demonstrate meaningful potential to enhance therapeutic efficacy, reduce the frequency of dosing, and improve safety.

Conclusion

Novel posterior segment drug delivery systems offer promising solutions for overcoming longstanding anatomical and physiological barriers. Continued innovation is essential for optimizing treatment outcomes and improving the management of retinal and choroidal diseases.