Ocular barriers and ocular drug delivery: Bridging the gap using nanomicelles as drug carriers

Abstract

Micelles came into existence in 1913 by G.S. Hartley by describing the self-assembling of the surface-active
agents above certain concentrations called critical micelle concentration. Incorporating a nanotechnology
approach in micelle formation results in the development of nanomicelles. Many novel drug delivery systems
were been discovered for delivering the drug to the ocular cavity. However, they were not promising enough to
give good bioavailability to the ocular tissues. It is mainly because of two major complex reasons First, where the
tear fluid which is produced continuously by lachrymal glands dilutes the effectiveness of the preparation thus
the preparation could not give its optimum effect. Second, the presence of goblet cells in the conjunctival coating
of the eye. Delivery of the drugs through the posterior chamber of the eye is much more tedious because of the
existence of the blood–retinal barrier, or the BRB which resembles a more complex blood–brain barrier. The
utilization of micelles favors the topical delivery on the ocular surface because the presence of surfactants helps
in solubilizing the drug in different barriers of the eye and thus intensifies the retention time of medication in the
ocular cavity. The nanomicelles offer many benefits for transporting the medication to the ocular cavity without
affecting the normal physiology of the eye. In this review article, efforts have been made to cover all the aspects
of nanomicelles in ophthalmic drug delivery.