Handheld OCT-A using spectrally encoded coherence tomography and reflectometry (Conference Presentation)

Optical coherence tomographic angiography (OCT-A) technologies have been primarily demonstrated on slit-lamp systems, which preclude imaging in infants, bedridden patients, or patients who are otherwise unable to be imaged upright. Current-generation OCT-A requires densely-sampled volumetric datasets for high vascular resolution imaging, but bulk motion artifacts, resulting from saccades or eye drifts, often distort anatomic features during long acquisitions. Here, we demonstrate handheld motion-artifact corrected OCT-A using spectrally encoded coherence tomography and reflectometry (SECTR). SECTR has advantageous over previously demonstrated handheld ophthalmic imagers by acquiring spatiotemporally co-registered, high-speed en face images of the retinal fundus using spectrally encoded reflectometry (SER) concurrently with OCT. The orthogonal priority acquisition axes of SER and OCT enables volumetric registration and motion-artifact compensation. We have incorporated several optomechanical improvements including novel snap-fit lens mounts for reduced size and weight and improved optical stability over our previous design. Additionally, we developed a method for reducing back reflections from a double-clad fiber by fusion-splicing a no-core fiber segment with a predefined geometry. Lastly, we demonstrate in vivo human OCT-A imaging of the optic nerve head and fovea. OCT and OCT-A images were motion-corrected using complementary motion information extracted from en face SER and cross-sectional OCT images. Here, OCT-A volumetric datasets were densely-sampled in small regions-of-interest within a large SER field-of-view to achieve high vascular resolution OCT-A while maintaining sufficient fiducials within SER images for motion registration. We believe our probe will enable point-of-care functional ophthalmic imaging.