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 Optoretinogram (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, post-processing, 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 CUDA (Compute Unified Device Architecture), is optimized for rapid and efficient data capture and processing. We reduced system complexity by integrating OCT, OCTA, and ORG protocols and reprogramming post-processing software. Our system, operating at a 400 kHz A-scan rate, supports both structural and functional imaging with a 5.0 μm 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 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 junction. Overall, this system, to our knowledge, offers the most comprehensive and high-speed imaging capabilities available, delivering detailed structural and functional insights into the living mouse retina.