An Integrative Analysis of Ocular Drug Delivery: Insights into Ocular Anatomy, Pathology, and Advanced Biocomposite and Nanotechnological Therapeutics

The complex anatomy and protective barriers of the eye, including the corneal epithelium, rapid tear clearance, and blood-ocular barriers, significantly limit topical ocular drug delivery, resulting in bioavailability as low as 1–5% with traditional formulations such as eye drops, ointments, and suspensions. This review thoroughly examines the obstacles in ocular drug delivery across major eye disorders—including glaucoma, cataracts, age-related macular degeneration, bacterial and fungal keratitis, diabetic retinopathy, and dry eye syndrome. It further underscores cutting-edge treatment platforms such as in situ gels, ocular inserts, and diverse nanocarriers—liposomes, nanoparticles, niosomes, dendrimers, nanosuspensions, and microemulsions—augmented by advanced techniques like iontophoresis and sonophoresis. Mucoadhesive biopolymers such as chitosan, PVA, and Carbopol, along with cutting-edge nanocomposites, drive advancements by markedly improving ocular retention, enhancing corneal penetration, and enabling sustained drug release while reducing irritation and systemic toxicity. Innovations in drug delivery have markedly improved patient adherence by minimising dosing intervals and enabling accurate delivery to posterior eye conditions such as glaucoma and age-related macular degeneration. Emerging research will focus on engineering hybrid nanocarriers that combine gene therapy and tissue engineering, aiming to boost stability, scalability, and accelerate effective clinical translation.