Drug delivery for the treatment of posterior segment diseases has become a
major challenge in the field of ophthalmology due to its restrictive barrier
functionalities. Blood-ocular barriers act as a physical barrier between the local blood
vessels, ocular tissues and fluids which restrict the passage of various solutes and fluids.
Ocular barriers may be classified as static and dynamic barriers. Static barrier include
sclera, Bruch’s membrane-choroid (BC), retinal pigment epithelium (RPE) and
conjunctiva while dynamic barriers include drug clearance mechanism through blood
and lymphatic vessels. Apart from above mentioned barriers, it is also imperative to
understand the role of enzymes and transporters in drug disposition. Overall, it is
essential to understand anatomy, physiology and disposition mechanisms of eye and
interaction between drug molecules/formulation with various ocular tissues in order to
design a successful drug delivery system.
Keywords: Eye, static barrier, dynamic barrier, sclera, Bruch’s membranechoroid,
Conjunctiva, Blood retinal barrier, transporters, metabolism, ocular drug
delivery.
