Adaptive optics optical coherence tomography at 1 MHz.

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optical Imaging

Background:

• Image acquisition speed is a key limitation for optical coherence tomography (OCT) in clinical and research settings.
• Adaptive optics (AO) enhances resolution in OCT but often requires slower acquisition speeds.

Purpose of the Study:

• To develop and validate a novel, ultra-high-speed adaptive optics-optical coherence tomography (AO-OCT) system for ophthalmic imaging.
• To overcome the speed limitations of current OCT systems for detailed retinal imaging.

Main Methods:

• Designed a multi-camera spectral-domain AO-OCT system operating at 790 nm.
• Incorporated a novel detection channel with four high-speed spectrometers and a 1x4 optical switch for sequential light reception.
• Achieved ultra-fast switching (50ns) without moving parts to maximize light usage and minimize camera dead-time.

Main Results:

• The system demonstrated an unprecedented acquisition speed of 1 million A-lines/s.
• Achieved 5.3 μm axial resolution in retinal tissue with high signal-to-noise ratio and dynamic range comparable to clinical OCT.
• Successfully imaged fine retinal structures, including individual retinal nerve fiber bundles and cone photoreceptors, in model and human eyes.

Conclusions:

• The developed MHz AO-OCT system represents the fastest ophthalmic OCT in the 700-915 nm spectral band.
• This technology significantly advances the potential for high-speed, high-resolution retinal imaging in ophthalmology.
• Enables detailed visualization of microstructures, potentially improving diagnosis and understanding of retinal diseases.