Drug delivery to the posterior segment of the eye.

Drug delivery into the posterior segment of the eye is complicated by the presence of the blood-ocular barrier. Strategies for delivering drugs to the posterior segment include systemic administration, modification of the blood-eye barrier, and local drug delivery. Recently, new topical treatments have emerged for the treatment of posterior eye disease. Iontophoretic, juxtascleral, and intravitreal routes can be used to achieve therapeutic levels in the posterior segment. Extended-release intravitreal drug delivery systems can achieve sustained therapeutic levels with the goal of providing a prolonged clinical benefit.