Development of a High-Speed Swept-Source OCT/OCTA/ORG System for Structural and Functional Imaging of the Living Mouse Retina

The mouse retina serves as a critical model for studying human eye diseases. Optical coherence tomography (OCT) has rapidly advanced as a technique for retinal imaging, with OCT angiography (OCTA) and optoretiongraphy (ORG) emerging as significant functional extensions. High-speed, multifunctional imaging systems markedly enhance the efficiency of experiments by enabling fast and comprehensive data collection from the living mouse retina. However, integrating both high-speed operations and multiple functionalities poses challenges in data acquisition, real-time processing, postprocessing, and system complexity. To address these challenges, we developed a high-speed imaging system leveraging a high-speed swept laser source and a high-speed digitizer for data acquisition. The data acquisition software, developed with C++ and Compute Unified Device Architecture (CUDA), is optimized for rapid and efficient data capture and processing. We reduced system complexity by integrating OCT, OCTA, and ORG protocols and reprogramming postprocessing software. Our system, operating at a 400 kHz A-scan rate, supports both structural and functional imaging with a 5.0 $\mu $ m axial resolution and consistent sensitivity of 53 dB across a 2 mm depth. Utilizing the temporal speckle averaging (TSA) technique, we achieved high contrast-to-noise ratio (CNR) images, allowing us to delineate retinal structures and blood vessels. For ORG analysis, we developed intensity-based and phase-based methods to evaluate the retina’s light-evoked responses. The intensity-based approach effectively detects photoreceptor elongation and scattering changes, while the phase-based method provides a highly sensitive detection with a temporal resolution of up to 1 ms, revealing subtle changes in the length of the outer segment (OS). Overall, this system, to our knowledge, offers the most comprehensive and high-speed imaging capabilities available, delivering detailed structural and functional insight into the living mouse retina.