As clinical research takes place to find new pharmaceutical options for treating retinal disease, a parallel effort is underway to develop devices and techniques that can deliver drugs to the posterior segment. This effort is complex in its very nature; in some cases, it involves drugs such as corticosteroids that have been used routinely by retina specialists for macular edema but that are not US Food and Drug Administration (FDA)-approved for this indication. In other cases, the technology being studied is highly conceptual but may eventually be able to be used for multiple applications employing a variety of pharmaceuticals.

In this issue of Retina Today, our cover focus is drug delivery to the posterior segment. The articles that we selected for this issue cover a broad range of topics in this category. Our authors discuss intravitreal injections and sustained-release implants, both with which we are familiar and have FDA-approved technologies or are currently in phase 3 trials. We also feature articles discussing transporter-targeted drug delivery, nanotechnology, suprachoroidal delivery, and iontopheresis.

Nanotechnology utilizes devices that are to scale with intracellular structures and molecules, and has the potential to be used for gene and cell delivery, drug and prosthetic delivery, and in surgical applications. Transporter-targeted drug delivery is a technology that takes advantage of nutrient transport systems to enhance permeability of the target tissue. Supra-choroidal drug delivery and iontopheresis are two other categories that are currently under investigation as possible means to effectively target the back of the eye. Suprachoroidal drug delivery uses an illuminated microcatheter and can potentially reach the posterior segment in an atraumatic manner; studies are underway. Iontopheresis uses an electrical field that, once activated, changes the permeability of ocular cells and may improve penetration to allow delivery. The technology is being studied for anterior segment uses and studies are planned for the posterior segment.

CONTINUING OUR SUCCESS
This is an exciting period in retina research. A number of other novel technologies are under investigation for drug delivery; we will be hearing more about them in the future as research progresses. Intravitreal injections have offered us the ability to help our patients and represent the most significant advances in retina since vitrectomy; however, no one wants to commit their patients to an indeterminate course of injections. Thus, it is important to continue our progress in research to find ways to medically treat retina diseases and reduce the current burden for our patients.