ABSTRACT
This chapter reviews the anatomical and physiological properties associated with limitations to ocular drug delivery. It enlightens the rationale for the use of the intravitreal drug delivery route, discusses the usefulness as well as the shortcomings of intravitreal therapies currently used in ophthalmic practice, and refers to the potential future innovative ideas for drug delivery designs in the context of the unmet clinical and engineering needs for intravitreal delivery systems. Intrinsic anatomic and physiologic properties of the eye impose qualitative and quantitative limitations to the design of an efficient drug delivery system. The eye is a relatively isolated organ that receives a small share of the cardiac blood flow. It is essentially a fluid-filled cavity engulfed by avascular tissues, and it has multiple blood-ocular barriers. Sulfur hexafluoride and perfluoropropane gas bubbles injected into the vitreous cavity may induce a temporary breakdown of the blood-aqueous barrier. This may alter the pharmacokinetics of intravitreal therapies.
