The complex barriers to drug delivery in the eye make it difficult for traditional ophthalmic preparations to reach pathological tissues in the posterior segment of the eye via ocular surface. Therefore, intravitreal drug injection has been widely used for treating posterior segment diseases, but this invasive approach to drug delivery has disadvantages such as short drug half-lives, repeated injections, and many complications. Ophthalmic nanodrug delivery systems, which can overcome ocular drug delivery barriers, enhance drug permeability, and improve drug bioavailability, now make it possible to efficiently deliver drugs to the posterior segment of the eye. However, the carrier materials utilized for nanomedicine delivery are inherently intricate, and substantial disparities exist among research findings, posing a hindrance to the subsequent advancement of pertinent drug formulations. Consequently, this review centers on the principal physiological obstacles encountered in ocular drug delivery, emphasizing the utilization of diverse nanomedicine delivery systems in posterior segment pathologies. It aims to delve into their research progress in posterior segment diseases and establish a safer, more effective therapeutic approach for treating these ocular conditions.