Optical Coherence Tomography with Fluorescein Optical Clearing for Transscleral Image Guidance

Background: Scattering of the sclera limits optical coherence tomography (OCT) imaging of deeper targets including lesions, malignancies, and other surgical targets. While existing applications of fluorescein dye are currently focused on fluorescence properties for tissue labeling, the absorption characteristics of the dye also hold potential for scleral tissue clearing. Methods: Fluorescein is investigated here to gauge the potential impact of its optical clearing on intrasurgical OCT guidance. Fluorescein was applied topically to ex vivo porcine and human eye models. OCT imaging was conducted over time to assess the increases in imaging depth due to fluorescein clearing. High-speed microscope-integrated OCT was used during pilot trabeculectomy surgery on cleared eye models to assess clearing applications in a surgical context. Results: The OCT depth of imaging increased with fluorescein concentration and application time. The effect saturates at a near-20% concentration with 50 min of application time, with a maximum signal increase of +15 dB. Reversal of the effect was observed following 10 min of rinsing. Conclusions: High-concentration fluorescein dye has novel applications as an optical clearing agent, increasing the OCT imaging depth through highly scattering biological tissue. These properties can be leveraged for improved image guidance in surgical contexts.