Integrated visible-light optical coherence tomography and fluorescence scanning laser ophthalmoscopy to image retinal ganglion cell axons.

Retinal ganglion cell (RGC) soma and axonal damage is a hallmark of optic neuropathies. Visible-light OCT fibergraphy (vis-OCTF) enables non-invasive imaging and quantitative assessment of individual RGC axon bundles; however, validating vis-OCTF using confocal fluorescence imaging of flat-mounted postmortem retina is less accurate due to structural alterations caused by flat-mount preparation and cannot be performed longitudinally. For in vivo vis-OCTF validation, we developed an integrated visible-light optical coherence tomography (vis-OCT) and fluorescence scanning laser ophthalmoscopy (SLO) system.

Swept-source visible-light optical coherence tomography.

We demonstrate the feasibility of swept-source visible-light optical coherence tomography (SS-vis-OCT). We used a fanout periodically poled lithium niobate (PPLN) crystal for second-harmonic generation (SHG) to convert a commercial near-infrared swept-source (NIR-SS) laser into a visible-light SS laser. To enhance SHG efficiency, we amplified the NIR-SS output with booster optical amplifiers (BOAs) and generated up to 580 µW of power.