Breaking barriers in ocular drug delivery for Uveitis: Advanced drug delivery systems, challenges and future prospects.

Uveitis is inflammation of the uvea, the middle layer of the eye which comprises of iris, ciliary body and choroid. Complications associated with uveitis include chronic pain, vision impairment and even blindness if not treated adequately. Conventional treatments for uveitis include immunosuppressive medications such as corticosteroids and biologics, which present challenges of low bioavailability due to complex anatomical structure of eye, rapid drug elimination, enzymatic degradation and the blood-retinal barrier. Consequently, they require frequent administration and are often associated with systemic side effects. In comparison to conventional drug delivery advanced drug delivery systems offer advantages such as targeted drug delivery, sustained drug release and reduction in side effects. A thorough literature search was conducted using Google Scholar, PubMed, covering publications from 2000 to 2024. The search terms included "uveitis," "pathology and pathophysiology of uveitis," "barriers in ocular drug delivery," and "uveitis conventional treatments." To refine the search results, "uveitis" was combined with different keywords such as "polymeric nanoparticles," "liposomes," "nanomicelles," "dendrimers," "nanoemulsions," "hydrogels," "implants," or "microneedles" to gather information related to each novel drug delivery system. Only English language studies were considered. The inclusion criteria encompassed both review and research articles specifically related to uveitis, with a focus on studies evaluating novel drug delivery systems for its treatment. Studies on ocular drug delivery systems unrelated to uveitis were excluded. No formal statistical analysis was conducted. This review highlights various advanced drug delivery approaches including polymeric nanoparticles, liposomes, nanomicelles, dendrimers, nanoemulsions, hydrogels, implants and microneedles for the treatment of uveitis.