Optical Clearing with Tartrazine Enables Deep Transscleral Imaging with Optical Coherence Tomography.

Suprachoroidal injections are a relatively new method of drug delivery to treat retinal disease. At present, it is difficult to visualize the distribution of injection-delivered product beneath the sclera into the suprachoroidal space. Imaging the suprachoroidal space with OCT is hindered by scattering of light from densely packed collagen fibers of the sclera, limiting depth penetration of the OCT light. In this Letter, we demonstrate the first use of tartrazine (Yellow 5) as an optical clearing agent for suprachoroidal research imaging with OCT in an ex vivo eye model. Our results show that this clearing agent dramatically improves visualization of the choroid and suprachoroidal space with transscleral OCT and allows for improved imaging of the location and extent of delivered suprachoroidal fluid. We believe these methods will enable use of optical techniques such as OCT to image through a variety of previously optically inaccessible, highly scattering tissue samples.