Optical clearing with tartrazine enables deep transscleral imaging with optical coherence tomography

Significance: Imaging deep structures with optical coherence tomography (OCT) is difficult in highly scattering biological tissue, such as the sclera. There is a need to visualize the suprachoroidal space and choroid through the sclera to study suprachoroidal drug delivery.

Aim: We aim to develop optical methods to image through the highly scattering sclera with a custom-built OCT system to visualize the suprachoroidal space and drug delivery within.

Approach: We developed a custom handheld OCT scanner to image the anterior segment and suprachoroidal space in ex vivo eye models. Tartrazine (Yellow 5) solution, which has been shown to optically clear biological tissue in the visible regime, was tested as a clearing agent to optimize near infrared OCT imaging through the sclera.

Results: Tartrazine dramatically increased OCT signal return from the deeper sclera and choroid and thus enabled visualization of the suprachoroidal drug delivery after transscleral injection.

Conclusions: We demonstrated successful optical clearing of the thick, porcine sclera with a compact handheld OCT system to image the suprachoroidal space. We believe there is broader potential to use optical clearing with handheld OCT for a variety of previously inaccessible, highly scattering tissue samples.