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Cai Y, Thouvenin O, Grieve K, Mecê P. Influence of static and dynamic ocular aberrations on full-field optical coherence tomography for in vivo high-resolution retinal imaging. OPTICS LETTERS 2024; 49:2209-2212. [PMID: 38691681 DOI: 10.1364/ol.515749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/21/2024] [Indexed: 05/03/2024]
Abstract
Under spatially incoherent illumination, time-domain full-field optical coherence tomography (FFOCT) offers the possibility to achieve in vivo retinal imaging at cellular resolution over a wide field of view. Such performance is possible, albeit there is the presence of ocular aberrations even without the use of classical adaptive optics. While the effect of aberrations in FFOCT has been debated these past years, mostly on low-order and static aberrations, we present, for the first time to our knowledge, a method enabling a quantitative study of the effect of statistically representative static and dynamic ocular aberrations on FFOCT image metrics, such as SNR, resolution, and image similarity. While we show that ocular aberrations can decrease FFOCT SNR and resolution by up to 14 dB and fivefold, we take advantage of such quantification to discuss different possible compromises between performance gain and adaptive optics complexity and speed, to optimize both sensor-based and sensorless FFOCT high-resolution retinal imaging.
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Shao W, Yi J. Non-interferometric volumetric imaging in living human retina by confocal oblique scanning laser ophthalmoscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:3576-3592. [PMID: 35781976 PMCID: PMC9208584 DOI: 10.1364/boe.457408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/06/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Three-dimensional (3D) imaging of the human retina is instrumental in vision science and ophthalmology. While interferometric retinal imaging is well established by optical coherence tomography (OCT), non-interferometric volumetric imaging in the human retina has been challenging up to date. Here, we report confocal oblique scanning laser ophthalmoscopy (CoSLO) to fill that void and harness non-interferometric optical contrast in 3D. CoSLO decouples the illumination and detection by utilizing oblique laser scanning and oblique imaging to achieve ∼4x better axial resolution than conventional SLO. By combining remote focusing, CoSLO permits the acquisition of depth signals in parallel and over a large field of view. Confocal gating is introduced by a linear sensor array to improve the contrast and resolution. For the first time, we reported non-interferometric 3D human retinal imaging with >20° viewing angle, and revealed detailed features in the inner, outer retina, and choroid. CoSLO shows potential to be another useful technique by offering 3D non-interferometric contrasts.
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Affiliation(s)
- Wenjun Shao
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, 21231, USA
- Department of Ophthalmology, Johns Hopkins University, Baltimore, Maryland, 21231, USA
| | - Ji Yi
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, 21231, USA
- Department of Ophthalmology, Johns Hopkins University, Baltimore, Maryland, 21231, USA
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Zhang M, Gofas-Salas E, Leonard BT, Rui Y, Snyder VC, Reecher HM, Mecê P, Rossi EA. Strip-based digital image registration for distortion minimization and robust eye motion measurement from scanned ophthalmic imaging systems. BIOMEDICAL OPTICS EXPRESS 2021; 12:2353-2372. [PMID: 33996234 PMCID: PMC8086453 DOI: 10.1364/boe.418070] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/13/2021] [Accepted: 03/16/2021] [Indexed: 05/22/2023]
Abstract
Retinal image-based eye motion measurement from scanned ophthalmic imaging systems, such as scanning laser ophthalmoscopy, has allowed for precise real-time eye tracking at sub-micron resolution. However, the constraints of real-time tracking result in a high error tolerance that is detrimental for some eye motion measurement and imaging applications. We show here that eye motion can be extracted from image sequences when these constraints are lifted, and all data is available at the time of registration. Our approach identifies and discards distorted frames, detects coarse motion to generate a synthetic reference frame and then uses it for fine scale motion tracking with improved sensitivity over a larger area. We demonstrate its application here to tracking scanning laser ophthalmoscopy (TSLO) and adaptive optics scanning light ophthalmoscopy (AOSLO), and show that it can successfully capture most of the eye motion across each image sequence, leaving only between 0.1-3.4% of non-blink frames untracked, while simultaneously minimizing image distortions induced from eye motion. These improvements will facilitate precise measurement of fixational eye movements (FEMs) in TSLO and longitudinal tracking of individual cells in AOSLO.
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Affiliation(s)
- Min Zhang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Denotes that each of these authors contributed equally to this work
| | - Elena Gofas-Salas
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Denotes that each of these authors contributed equally to this work
| | - Bianca T Leonard
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Yuhua Rui
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Eye center of Xiangya Hospital, Central South University; Hunan Key Laboratory of Ophthalmology; Changsha, Hunan 410008, China
| | - Valerie C Snyder
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Hope M Reecher
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Pedro Mecê
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Ethan A Rossi
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15261, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Mecê P, Gofas-Salas E, Rui Y, Zhang M, Sahel JA, Rossi EA. Spatial-frequency-based image reconstruction to improve image contrast in multi-offset adaptive optics ophthalmoscopy. OPTICS LETTERS 2021; 46:1085-1088. [PMID: 33649663 PMCID: PMC9202470 DOI: 10.1364/ol.417903] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Off-axis detection methods in adaptive optics (AO) ophthalmoscopy can enhance image contrast of translucent retinal structures such as cone inner segments and retinal ganglion cells. Here, we propose a 2D optical model showing that the phase contrast produced by these methods depends on the offset orientation. While one axis provides an asymmetric light distribution, hence high phase contrast, the perpendicular axis provides a symmetric one, thus substantially lower contrast. We support this model with in vivo human data acquired with a multi-offset AO scanning light ophthalmoscope. Then, using this finding, we provide a post-processing method, named spatial-frequency-based image reconstruction, to optimally combine images from different off-axis detector orientations, significantly increasing the structural cellular contrast of in vivo human retinal neurons such as cone inner segment, putative rods, and retinal ganglion cells.
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Affiliation(s)
- Pedro Mecê
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Elena Gofas-Salas
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Yuhua Rui
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Eye center of Xiangya Hospital, Central South Univeristy; Hunan Key Laboratory of Ophthalmology; Changsha, Hunan, China
| | - Min Zhang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ethan A. Rossi
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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Blavier M, Glanc M, Rousset G. Analysis of the impact of optical aberrations in en-face full-field OCT microscopy. OPTICS EXPRESS 2021; 29:2204-2226. [PMID: 33726421 DOI: 10.1364/oe.403432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Optical coherence tomography (OCT) is a powerful technique for cross-sectioning imaging. However, the lateral resolution may be degraded by optical aberrations originating from the sample or the setup. We present an extensive quantitative study of the impact of aberrations in time-domain en-face full-field OCT (FFOCT). Using an adaptive optics loop integrated in an FFOCT setup, a deformable mirror is used to introduce low-order calibrated aberrations. The experimental analysis of both the line spread functions (SF) and the complex object images has allowed us to measure the loss in contrast and the impact on lateral spatial resolution. We demonstrate that the frequency content of FFOCT image spectra in terms of signal-to-noise ratio and cutoff frequency is degraded by aberrations but remains much higher than in conventional incoherent images. Line SF profiles in conventional imaging display widening, whereas in FFOCT they display oscillations, leading to the possible perception of preserved resolution. Nevertheless, for complex objects, the aberration image blurring is strong due to the convolution process by the point SF, resulting in a significant filtering of the image spatial spectrum.
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Mecê P, Groux K, Scholler J, Thouvenin O, Fink M, Grieve K, Boccara C. Coherence gate shaping for wide field high-resolution in vivo retinal imaging with full-field OCT. BIOMEDICAL OPTICS EXPRESS 2020; 11:4928-4941. [PMID: 33014591 PMCID: PMC7510855 DOI: 10.1364/boe.400522] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/20/2020] [Accepted: 07/29/2020] [Indexed: 05/05/2023]
Abstract
Allying high-resolution with a large field-of-view (FOV) is of great importance in the fields of biology and medicine, but it is particularly challenging when imaging non-flat living samples such as the human retina. Indeed, high-resolution is normally achieved with adaptive optics (AO) and scanning methods, which considerably reduce the useful FOV and increase the system complexity. An alternative technique is time-domain full-field optical coherence tomography (FF-OCT), which has already shown its potential for in-vivo high-resolution retinal imaging. Here, we introduce coherence gate shaping for FF-OCT, to optically shape the coherence gate geometry to match the sample curvature, thus achieving a larger FOV than previously possible. Using this instrument, we obtained high-resolution images of living human photoreceptors close to the foveal center without AO and with a 1 mm × 1 mm FOV in a single shot. This novel advance enables the extraction of photoreceptor-based biomarkers with ease and spatiotemporal monitoring of individual photoreceptors. We compare our findings with AO-assisted ophthalmoscopes, highlighting the potential of FF-OCT, as a compact system, to become a routine clinical imaging technique.
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Affiliation(s)
- Pedro Mecê
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Kassandra Groux
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Jules Scholler
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Olivier Thouvenin
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Mathias Fink
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Kate Grieve
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012, Paris, France
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012, France
| | - Claude Boccara
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
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Mecê P, Gofas-Salas E, Paques M, Grieve K, Meimon S. Optical Incoherence Tomography: a method to generate tomographic retinal cross-sections with non-interferometric adaptive optics ophthalmoscopes. BIOMEDICAL OPTICS EXPRESS 2020; 11:4069-4084. [PMID: 32923029 PMCID: PMC7449754 DOI: 10.1364/boe.396937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/12/2020] [Accepted: 06/16/2020] [Indexed: 05/05/2023]
Abstract
We present Optical Incoherence Tomography (OIT): a completely digital method to generate tomographic retinal cross-sections from en-face through-focus image stacks acquired by non-interferometric imaging systems, such as en-face adaptive optics (AO)-ophthalmoscopes. We demonstrate that OIT can be applied to different imaging modalities using back-scattered light, including systems without inherent optical sectioning and, for the first time, multiply-scattered light, revealing a distinctive cross-sectional view of the retina. The axial dimension of OIT cross-sections is given in terms of focus position rather than optical path, as in OCT. We explore this property to guide focus position in cases where the user is "blind" focusing, allowing precise plane selection for en-face imaging of retinal pigment epithelium, the vascular plexuses and translucent retinal neurons, such as photoreceptor inner segments and retinal ganglion cells, using respectively autofluorescence, motion contrast and split detection techniques.
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Affiliation(s)
- Pedro Mecê
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris, France
| | - Elena Gofas-Salas
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012, France
| | - Michel Paques
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012, France
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012, Paris, France
| | - Kate Grieve
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012, France
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012, Paris, France
| | - Serge Meimon
- DOTA, ONERA, Université Paris Saclay F-91123 Palaiseau, France
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Mecê P, Scholler J, Groux K, Boccara C. High-resolution in-vivo human retinal imaging using full-field OCT with optical stabilization of axial motion. BIOMEDICAL OPTICS EXPRESS 2020; 11:492-504. [PMID: 32010530 PMCID: PMC6968740 DOI: 10.1364/boe.381398] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/12/2019] [Accepted: 12/16/2019] [Indexed: 05/05/2023]
Abstract
Time-domain full-field OCT (FF-OCT) represents an imaging modality capable of recording high-speed en-face sections of a sample at a given depth. One of the biggest challenges to transfer this technique to image in-vivo human retina is the presence of continuous involuntary head and eye axial motion during image acquisition. In this paper, we demonstrate a solution to this problem by implementing an optical stabilization in an FF-OCT system. This was made possible by combining an FF-OCT system, an SD-OCT system, and a high-speed voice-coil translation stage. B-scans generated by the SD-OCT were used to measure the retina axial position and to drive the position of the high-speed voice coil translation stage, where the FF-OCT reference arm is mounted. Closed-loop optical stabilization reduced the RMS error by a factor of 7, significantly increasing the FF-OCT image acquisition efficiency. By these means, we demonstrate the capacity of the FF-OCT to resolve cone mosaic as close as 1.5 o from the fovea center with high consistency and without using adaptive optics.
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