Sustained transscleral drug delivery

Transscleral delivery is an emerging, high-potential method for delivering drugs to the posterior eye. If successful, it could offer non-invasiveness comparable to drops and delivery efficiency comparable to intravitreal injection. However, there are numerous challenges to be overcome before transscleral delivery will be a significant treatment option. The resistance of the sclera is extremely well understood, but the other tissues, especially the retinal pigment epithelium, clearly demand more attention and the effect of drug chemistry remains poorly understood. In this review, the major research on transscleral delivery with an emphasis on current understanding of these points and open questions for the field is summarized.