Phase-Locked Time-Stretch Optical Coherence Tomography for Contrast-Enhanced Retinal Microangiography

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Optical coherence tomography angiography (OCTA) revolutionized retinal vascular imaging with non-invasive, high-resolution visualization.
• Challenges persist in balancing field of view, resolution, and contrast for deep retinal microvasculature imaging.

Purpose of the Study:

• To develop a novel phase-locked time-stretch OCT angiography system to overcome current imaging limitations.
• To enhance visualization of superficial and deep retinal capillary plexuses and the choriocapillaris.

Main Methods:

• A 5-MHz A-line rate system with sub-nm phase sensitivity was engineered.
• A dual chirped fiber Bragg grating architecture provided an extended coherence length (~10 mm) and 102-nm bandwidth.
• A time-stretch analog-to-digital converter enabled 2-mm imaging depth with high spatial resolution.

Main Results:

• The system achieved high-contrast, depth-encoded mapping of retinal microvasculature.
• Demonstrated enhanced resolution, improved contrast, and faster imaging speeds compared to state-of-the-art systems.
• Successfully visualized superficial and deep capillary plexuses and the choriocapillaris.

Conclusions:

• The developed phase-locked time-stretch OCT angiography system significantly advances retinal microvasculature imaging.
• Offers potential for improved diagnosis and monitoring of retinal diseases (e.g., AMD, diabetic retinopathy) and systemic conditions (e.g., Alzheimer's).