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Pedro Mecê, Jules Scholler, Kassandra Groux, Yao Cai, Michel Paques, Kate Grieve, Claude Boccara; Adaptive-glasses Full-Field OCT for high-resolution retinal imaging over a large field-of-view. Invest. Ophthalmol. Vis. Sci. 2021;62(8):9.
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© ARVO (1962-2015); The Authors (2016-present)
The highest three-dimensional (3D) resolution possible in in-vivo retinal imaging is achieved by combining optical coherence tomography (OCT) and adaptive optics. However, this combination brings important limitations, such as small field-of-view and complex, cumbersome systems, preventing so far clinical deployment. Here, we introduce Adaptive-Glasses Full-Field OCT (FFOCT), a retinal imaging system allying high-resolution, high frame rate (300Hz), 5° FOV in a compact system (footprint: 30cm by 50cm).
We used our retinal imager combining a time-domain FFOCT and an SDOCT, enabling correction of axial eye motion in real-time. We previously demonstrated the capacity of this system to achieve foveal cone mosaic imaging without the use of AO, owing to the low sensitivity to ocular aberrations of the FFOCT when using spatially incoherent light, mostly affecting the signal to noise ratio (SNR). To increase the SNR, we implemented a lens-based sensorless AO approach using a multi-actuator adaptive lens (MAL) positioned in front of the eye, like prescribed eyeglasses, in a technique we call the adaptive-glasses approach. The SDOCT signal was used as a merit function for the wavefront optimization.
The FFOCT SNR was enhanced up to a factor of 10 by using the MAL for a dilated pupil. The MAL can adjust the focus axial position within the retina, to image structures in the inner retina as the nerve fiber layer with an 8 µm axial resolution. Moreover, owing to the combination of FFOCT with the adaptive-glasses approach, we can acquire high-resolution FFOCT images over a 5° FOV, without apparent anisoplanatism. This unprecedented combination of wide FOV and high-resolution facilitated important clinical tasks to diagnose retinal disorders, such as image montaging and the computation of photoreceptor-based biomarkers.
We showed that the combination of FFOCT, which presents a weaker sensitivity to symmetric aberrations in terms of lateral resolution , and the adaptive-glasses approach, to increase the SNR of FF-OCT image and to favor anisoplanatic correction, opens a new avenue to wide FOV high-resolution retinal imaging in a compact imaging system configuration, taking up essential challenges to facilitate clinical deployment of AO-OCT. The proposed system is moving to the Quinze Vingts National Ophthalmology Hospital to start clinical trials in the beginning of January 2021.
This is a 2021 ARVO Annual Meeting abstract.
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