Optimization of handheld spectrally encoded coherence tomography and reflectometry for point-of-care ophthalmic diagnostics

Traditional benchtop OCT systems require upright patient fixation and often impede ophthalmic imaging in bedridden, uncooperative, and pediatric patients. Point-of-care OCT systems have demonstrated ophthalmic imaging in supine patients. However, manually aligning and correcting for refractive power variations between patient eyes to ensure optimal image quality can be clinically cumbersome with point-of-care imaging systems. Here, we demonstrate our improved handheld spectrally encoded coherence tomography and reflectometry (HH-SECTR) imaging probe with mechanical focus-adjust and improved optical throughput in a clinically robust form-factor. SECTR uses spatiotemporally co-registered multimodal spectrally encoded reflectometry (SER) and OCT acquisition for volumetric motion-correction and retinal mosaicking. Our previous HH-SECTR prototype had three major limitations: 1) poor alignment stability caused by reduced mechanical stiffness in a completely rapid-prototyped resin body; 2) lossy SER optical throughput; and 3) manual focus adjust that was cumbersome during point-of-care imaging. Here, we demonstrate optical and optomechanical design improvements to address these limitations, including a modular aluminum probe chassis and increased optical power throughput for sustained system alignment and imaging performance. We have also incorporated a mechanical focusing subsystem to correct refractive errors, which can be integrated with our acquisition software for hands-free focus tracking. We demonstrate in vivo human retinal imaging, and mechanical focusing capabilities using a stationary model eye and stepping through +/- 10 diopters focal shift. We predict the addition of focusing capabilities and design improvements in form-factor and optical throughput to our HH-SECTR probe will benefit clinical translation and point-of-care multimodal OCT imaging.