Ocular drug delivery remains a formidable challenge in pharmaceutical sciences owing to the unique anatomical and physiological barriers of the eye, including the tear film, corneal epithelium, and blood-retinal barrier, which collectively limit the bioavailability of conventionally administered ophthalmic formulations. The aim of this review is to consolidate current advances in ocular drug delivery systems with emphasis on nanotechnology-based carriers, controlled-release platforms, and emerging therapeutic modalities. Conventional systems such as eye drops, ointments, and suspensions achieve limited precorneal residence and sub-therapeutic drug levels, necessitating the development of sophisticated delivery platforms. Modern strategies encompassing polymeric nanoparticles, liposomes, solid lipid nanoparticles (SLN), nanomicelles, dendrimers, and nanostructured lipid carriers (NLC) have demonstrated markedly enhanced corneal permeation and sustained drug release profiles in preclinical and clinical studies. Advanced platforms including ocular implants, in situ gelling systems, microneedles, and drug-loaded contact lenses represent transformative approaches that minimize dosing frequency while maximizing posterior segment targeting. Mechanisms underpinning controlled release such as mucoadhesion, penetration enhancement, and stimulus-responsive gelation are discussed in the context of glaucoma, posterior segment diseases, and infectious/inflammatory disorders. Despite significant technological advances, challenges related to regulatory compliance, scale-up manufacturing, ocular biocompatibility, and clinical translation continue to limit widespread adoption. This review highlights the critical importance of nanotechnology and advanced drug delivery engineering in reshaping the future landscape of ophthalmic therapeutics.