How liposomes pave the way for ocular drug delivery after topical administration

The eye is one of the most specialized organs in the body; one of its flawless functions is vigorously controlling the foreign materials' entrance to the eye. On the other hand, this feature made it challenging to deliver drug molecules to the eye chamber for therapeutic purposes. Other obstacles related to pharmaceuticals' low efficacy are short resistance time on the eye surfaces because of tear and nasolacrimal drainage. The advent of novel drug delivery systems (DDSs), like nanoparticles, was a milestone to overcome these problems, provided they were adeptly designed. In other words, all parameters influencing DDSs must be considered to attain the desired efficacy. This review discusses liposomes' essential characteristics as one of the most favored carriers that can affect the ocular drug bioavailability and efficacy. Here, we discussed the physiology of the eye, the mechanics of medicine distribution, and other factors affecting drug delivery. Then, all of the liposome's features, including composition, physicochemical properties, and drug targeting capability, which may alter the local distribution of the medication to the eye, were reviewed. In this review paper, prior investigations' outcomes are discussed to create appropriate liposomal vesicles for efficient ocular drug delivery.