Breaking Barriers in Eye Treatment: Polymeric Nano-Based Drug-Delivery System for Anterior Segment Diseases and Glaucoma

Abstract

The eye has anatomical structures that function as robust static and dynamic barriers, limiting the penetration, residence time, and bioavailability of medications administered topically. The development of polymeric nano-based drug-delivery systems (DDS) could be the solution to these challenges: it can pass through ocular barriers, offering higher bioavailability of administered drugs to targeted tissues that are otherwise inaccessible; it can stay in ocular tissues for longer periods of time, requiring fewer drug administrations; and it can be made up of polymers that are biodegradable and nano-sized, minimizing the undesirable effects of the administered molecules. Therefore, therapeutic innovations in polymeric nano-based DDS have been widely explored for ophthalmic drug-delivery applications. In this review, we will give a comprehensive overview of polymeric nano-based drug-delivery systems (DDS) used in the treatment of ocular diseases. We will then examine the current therapeutic challenges of various ocular diseases and analyze how different types of biopolymers can potentially enhance our therapeutic options. A literature review of the preclinical and clinical studies published between 2017 and 2022 was conducted. Thanks to the advances in polymer science, the ocular DDS has rapidly evolved, showing great promise to help clinicians better manage patients.

Vesicular Drug Delivery Systems: Promising Approaches in Ocular Drug Delivery

“…The blood–ocular barrier (BOB) system includes the anterior blood–aqueous barrier (BAB) and the posterior blood–retinal barrier (BRB) [ 20 ]. The BAB, found in the anterior compartment of the eye, consists of vascular endothelium without pores covering the iris blood vessels and tight junctions linking the apical portions of neighboring epithelial cells of the non-pigmented ciliary body epithelium [ 20 ]. This structure prevents drug entry from the plasma into the aqueous humor [ 20 ].…”

“…The BAB, found in the anterior compartment of the eye, consists of vascular endothelium without pores covering the iris blood vessels and tight junctions linking the apical portions of neighboring epithelial cells of the non-pigmented ciliary body epithelium [ 20 ]. This structure prevents drug entry from the plasma into the aqueous humor [ 20 ]. Nevertheless, the BAB is still not an absolute barrier due to the porous capillaries in the ciliary body stroma [ 20 ].…”

“…This structure prevents drug entry from the plasma into the aqueous humor [ 20 ]. Nevertheless, the BAB is still not an absolute barrier due to the porous capillaries in the ciliary body stroma [ 20 ]. These permeable capillaries, serving as a secondary source of plasma protein leakage to the iris, also facilitate the entry of small molecules into the iridial circulation [ 20 ].…”

“…Nevertheless, the BAB is still not an absolute barrier due to the porous capillaries in the ciliary body stroma [ 20 ]. These permeable capillaries, serving as a secondary source of plasma protein leakage to the iris, also facilitate the entry of small molecules into the iridial circulation [ 20 ]. The BRB primarily hinders drug diffusion into the retina after systemic circulation [ 20 ].…”

“…These permeable capillaries, serving as a secondary source of plasma protein leakage to the iris, also facilitate the entry of small molecules into the iridial circulation [ 20 ]. The BRB primarily hinders drug diffusion into the retina after systemic circulation [ 20 ]. The BRB found in the posterior compartment can be further categorized into the inner and outer BRB [ 20 ].…”