New ophthalmic drug delivery systems.

For decades, topical ophthalmic drug administration through the use of eye  drops has been the most widely used technique for the treatment of eye diseases. The development of galenic formulation has led to the use and commercialization of new formulations, such as suspensions, emulsions, and  ophthalmic ointments that increase residence time in the site of  action. Recently, new administration systems have been developed, such as  devices and inserts that provide the sustained release of active substance. Some of these systems are already available on the market, whereas others are still undergoing clinical trials, such as promising systems based on nanostructures (nanocapsules, cyclodextrins, nanoemulsions, etc.). Similarly,  various formulations and devices have been developed in the field of intravitreal administration, with different implants available on the European  market for the treatment of age-related macular degeneration (AMD), diabetic  macular edema, or infections that affect the posterior segment. This review  includes current developments in ophthalmic topical and intravitreal drug  administration routes as well as those under investigation.