Visible light optical coherence tomography (VIS-OCT) is an emerging ophthalmic imaging method uniquely featured by ultrahigh depth resolution, retinal microvascular oximetry, and distinct scattering contrast in the visible spectral range. However, the clinical utility of VIS-OCT is impeded by the fundamental trade-off between the imaging depth range and axial resolution, determined by the spectral resolution and bandwidth respectively. While the full potential of VIS-OCT is leveraged by a broad bandwidth, the imaging depth is inversely sacrificed. The effective depth range is further limited by the wavelength-dependent roll-off that the signal-to-noise ratio (SNR) reduces in the deeper imaging range, more so in shorter wavelength. To address this trade-off, we developed a second-generation dual-channel VIS-OCT system including the first linear-in-k VIS-OCT spectrometer, reference pathlength modulation, and per A-line noise cancellation. All combined, we have achieved 7.2dB roll-off over the full 1.74 mm depth range (water) with shot-noise limited performance. The system uniquely enables >60° wide-field imaging over large retinal curvature at peripheral retina and optic nerve head, as well as high-definition imaging at ultrahigh 1.3 um depth resolution (water). The dual-channel design includes a conventional near infrared (NIR) channel, compatible with Doppler OCT and OCT angiography (OCTA). The comprehensive structure-function measurement by 2nd-Gen VIS-OCT system is a significant advance towards broader adaptation of VIS-OCT in clinical applications.

Visible light optical coherence tomography (VIS-OCT) is an emerging ophthalmic imaging method featuring ultrahigh depth resolution, retinal microvascular oximetry, and distinct scattering contrast in the visible spectral range. The clinical utility of VIS-OCT is hampered by the fundamental trade-off between the imaging depth range and axial resolution, which are determined by the spectral resolution and bandwidth, respectively. While the full potential of VIS-OCT is leveraged by a broad bandwidth, the imaging depth is inversely sacrificed. The effective depth range is further limited, especially in the shorter wavelengths, by the spectrally dependent roll-off of the signal-to-noise ratio (SNR). To address this trade-off, we developed a second-generation (2nd Gen) dual-channel VIS-OCT system with three major advancements including the first linear-in-K VIS-OCT spectrometer to decrease the roll-off, reference pathlength modulation to expand the imaging depth range, and per-A-line noise cancellation to remove excess noise, Due to these unique designs. this system achieves 7.2 dB roll-off over the full 1.74 mm depth range (water) with shot-noise limited performance. The system uniquely enables > 60° wide-field imaging which would allow simultaneous imaging of the peripheral retina and optic nerve head, as well as ultrahigh 1.3 µm depth resolution (water). Benefiting from the additional near-infrared (NIR) channel of the dual-channel design, this system was compatible with Doppler OC T and OCT angiography (OCTA). The comprehensive structure-function measurements enabled by this second-generation dual-channel VIS-OCT system is a significant advance towards adoption of VIS-OCT in clinical applications.

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