Drug delivery to treat ocular diseases is one of the most challenging fields, due
to complex anatomy of eye and its physiological barriers like precorneal loss and the
presence of biological barriers, especially in the posterior segment of the eye. Although
topical eye drop administration is usually preferred to treat disorders of the eye, the
biological protecting factors lead to low ocular absorption and poor bioavailability (1–
10%). An efficient ocular drug delivery system, which can provide maximum precorneal
residence time, overcome ocular barriers and sustain delivery of drugs following topical
administration is desirable. Nanotechnology is an emerging field in drug delivery and
considerable research is taking place towards the development of nanotechnology-based
ocular drug delivery systems. Because of their ability to avoid various biological barriers
and providing targeted and sustained drug delivery to various ocular tissues,
nanotechnology-based formulations paved the approaches for efficient ophthalmic drug
delivery for both the anterior and posterior segments of eye. This review discusses a variety
of nanocarriers, such as nanoparticles, nanosuspension, liposomes, niosomes, discomes,
micelles, dendrimers and microemulsion developed for the ocular delivery of many drugs.
Some of them have shown promising results for improving ocular bioavailability. This
review also attempts to extend the information on recently issued and filed patents on
nanotechnology-based ocular drug delivery systems in the last few years.
Keywords: Nanotechnology, ocular, drug delivery, nanocarriers, nanoparticles,
nanosuspensions, liposomes, niosomes, discomes, micelles, dendrimers,
microemulsion, patents.
