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Kim TH, Ma G, Son T, Yao X. Functional Optical Coherence Tomography for Intrinsic Signal Optoretinography: Recent Developments and Deployment Challenges. Front Med (Lausanne) 2022; 9:864824. [PMID: 35445037 PMCID: PMC9013890 DOI: 10.3389/fmed.2022.864824] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/16/2022] [Indexed: 11/13/2022] Open
Abstract
Intrinsic optical signal (IOS) imaging of the retina, also termed as optoretinogram or optoretinography (ORG), promises a non-invasive method for the objective assessment of retinal function. By providing the unparalleled capability to differentiate individual retinal layers, functional optical coherence tomography (OCT) has been actively investigated for intrinsic signal ORG measurements. However, clinical deployment of functional OCT for quantitative ORG is still challenging due to the lack of a standardized imaging protocol and the complication of IOS sources and mechanisms. This article aims to summarize recent developments of functional OCT for ORG measurement, OCT intensity- and phase-based IOS processing. Technical challenges and perspectives of quantitative IOS analysis and ORG interpretations are discussed.
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Affiliation(s)
- Tae-Hoon Kim
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Guangying Ma
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Taeyoon Son
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Xincheng Yao
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
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2
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Detection of cellular micromotion by advanced signal processing. Sci Rep 2020; 10:20078. [PMID: 33208817 PMCID: PMC7675976 DOI: 10.1038/s41598-020-77015-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/29/2020] [Indexed: 11/30/2022] Open
Abstract
Cellular micromotion—a tiny movement of cell membranes on the nm-µm scale—has been proposed as a pathway for inter-cellular signal transduction and as a label-free proxy signal to neural activity. Here we harness several recent approaches of signal processing to detect such micromotion in video recordings of unlabeled cells. Our survey includes spectral filtering of the video signal, matched filtering, as well as 1D and 3D convolutional neural networks acting on pixel-wise time-domain data and a whole recording respectively.
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3
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Yao X, Kim TH. Fast intrinsic optical signal correlates with activation phase of phototransduction in retinal photoreceptors. Exp Biol Med (Maywood) 2020; 245:1087-1095. [PMID: 32558598 DOI: 10.1177/1535370220935406] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
IMPACT STATEMENT As the center of phototransduction, retinal photoreceptors are responsible for capturing and converting photon energy to bioelectric signals for following visual information processing in the retina. This article summarizes experimental observation and discusses biophysical mechanism of fast photoreceptor-intrinsic optical signal (IOS) correlated with early phase of phototransduction. Quantitative imaging of fast photoreceptor-IOS may provide objective optoretinography to advance the study and diagnosis of age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and other eye diseases that can cause photoreceptor dysfunctions.
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Affiliation(s)
- Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.,Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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4
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Lu Y, Liu C, Yao X. In vivo super-resolution imaging of transient retinal phototropism evoked by oblique light stimulation. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-4. [PMID: 29752801 PMCID: PMC5946809 DOI: 10.1117/1.jbo.23.5.050502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 04/19/2018] [Indexed: 05/28/2023]
Abstract
Rod-dominated transient retinal phototropism (TRP) has been observed in freshly isolated retinas, promising a noninvasive biomarker for objective assessment of retinal physiology. However, in vivo mapping of TRP is challenging due to its subcellular signal magnitude and fast time course. We report here a virtually structured detection-based super-resolution ophthalmoscope to achieve subcellular spatial resolution and millisecond temporal resolution for in vivo imaging of TRP. Spatiotemporal properties of in vivo TRP were characterized corresponding to variable light intensity stimuli, confirming that TRP is tightly correlated with early stages of phototransduction.
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Affiliation(s)
- Yiming Lu
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
| | - Changgeng Liu
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
| | - Xincheng Yao
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
- University of Illinois at Chicago, Department of Ophthalmology and Visual Sciences, Chicago, Illinois, United States
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5
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Wang B, Lu Y, Yao X. In vivo optical coherence tomography of stimulus-evoked intrinsic optical signals in mouse retinas. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:96010. [PMID: 27653936 PMCID: PMC5030472 DOI: 10.1117/1.jbo.21.9.096010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/26/2016] [Indexed: 05/22/2023]
Abstract
Intrinsic optical signal (IOS) imaging promises a noninvasive method for advanced study and diagnosis of eye diseases. Before pursuing clinical applications, it is essential to understand anatomic and physiological sources of retinal IOSs and to establish the relationship between IOS distortions and eye diseases. The purpose of this study was designed to demonstrate the feasibility of <italic<in vivo</italic< IOS imaging of mouse models. A high spatiotemporal resolution spectral domain optical coherence tomography (SD-OCT) was employed for depth-resolved retinal imaging. A custom-designed animal holder equipped with ear bar and bite bar was used to minimize eye movements. Dynamic OCT imaging revealed rapid IOS from the photoreceptor’s outer segment immediately after the stimulation delivery, and slow IOS changes were observed from inner retinal layers. Comparative photoreceptor IOS and electroretinography recordings suggested that the fast photoreceptor IOS may be attributed to the early stage of phototransduction before the hyperpolarization of retinal photoreceptor.
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Affiliation(s)
- Benquan Wang
- University of Illinois at Chicago, Department of Bioengineering, 851 South Morgan Street, Chicago, Illinois 60607, United States
| | - Yiming Lu
- University of Illinois at Chicago, Department of Bioengineering, 851 South Morgan Street, Chicago, Illinois 60607, United States
| | - Xincheng Yao
- University of Illinois at Chicago, Department of Bioengineering, 851 South Morgan Street, Chicago, Illinois 60607, United States
- University of Illinois at Chicago, Department of Ophthalmology and Visual Sciences, 1855 West Taylor Street, Chicago, Illinois 60612, United States
- Address all correspondence to: Xincheng Yao, E-mail:
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6
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Wang B, Yao X. In vivo intrinsic optical signal imaging of mouse retinas. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9693:96930H. [PMID: 28163346 PMCID: PMC5289717 DOI: 10.1117/12.2212810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Intrinsic optical signal (IOS) imaging is a promising noninvasive method for advanced study and diagnosis of eye diseases. Before pursuing clinical applications, more IOS studies employing animal models are necessary to establish the relationship between IOS distortions and eye diseases. Ample mouse models are available for investigating the relationship between IOS distortions and eye diseases. However, in vivo IOS imaging of mouse retinas is challenging due to the small ocular lens (compared to frog eyes) and inevitable eye movements. We report here in vivo IOS imaging of mouse retinas using a custom-designed functional OCT. The OCT system provided high resolution (3 μm) and high speed (up to 500 frames/s) imaging of mouse retinas. An animal holder equipped with a custom designed ear bar and bite bar was used to minimize eye movement due to breathing and heartbeats. Residual eye movement in OCT images was further compensated by accurate image registration. Dynamic OCT imaging revealed rapid IOSs from photoreceptor outer segments immediately (<10 ms) after the stimulation delivery, and unambiguous IOS changes were also observed from inner retinal layers with delayed time courses compared to that of photoreceptor IOSs.
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Affiliation(s)
- Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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Yao X, Wang B. Intrinsic optical signal imaging of retinal physiology: a review. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:090901. [PMID: 26405819 PMCID: PMC4689108 DOI: 10.1117/1.jbo.20.9.090901] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/31/2015] [Indexed: 05/09/2023]
Abstract
Intrinsic optical signal (IOS) imaging promises to be a noninvasive method for high-resolution examination of retinal physiology, which can advance the study and diagnosis of eye diseases. While specialized optical instruments are desirable for functional IOS imaging of retinal physiology, in depth understanding of multiple IOS sources in the complex retinal neural network is essential for optimizing instrument designs. We provide a brief overview of IOS studies and relationships in rod outer segment suspensions, isolated retinas, and intact eyes. Recent developments of line-scan confocal and functional optical coherence tomography (OCT) instruments have allowed in vivo IOS mapping of photoreceptor physiology. Further improvements of the line-scan confocal and functional OCT systems may provide a feasible solution to pursue functional IOS mapping of human photoreceptors. Some interesting IOSs have already been detected in inner retinal layers, but better development of the IOS instruments and software algorithms is required to achieve optimal physiological assessment of inner retinal neurons.
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Affiliation(s)
- Xincheng Yao
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
- University of Illinois at Chicago, Department of Ophthalmology and Visual Sciences, Chicago, Illinois 60612, United States
| | - Benquan Wang
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
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8
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Teussink MM, Cense B, van Grinsven MJ, Klevering BJ, Hoyng CB, Theelen T. Impact of motion-associated noise on intrinsic optical signal imaging in humans with optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:1632-47. [PMID: 26137369 PMCID: PMC4467722 DOI: 10.1364/boe.6.001632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/04/2015] [Accepted: 04/04/2015] [Indexed: 06/04/2023]
Abstract
A growing body of evidence suggests that phototransduction can be studied in the human eye in vivo by imaging of fast intrinsic optical signals (IOS). There is consensus concerning the limiting influence of motion-associated imaging noise on the reproducibility of IOS-measurements, especially in those employing spectral-domain optical coherence tomography (SD-OCT). However, no study to date has conducted a comprehensive analysis of this noise in the context of IOS-imaging. In this study, we discuss biophysical correlates of IOS, and we address motion-associated imaging noise by providing correctional post-processing methods. In order to avoid cross-talk of adjacent IOS of opposite signal polarity, cellular resolution and stability of imaging to the level of individual cones is likely needed. The optical Stiles-Crawford effect can be a source of significant IOS-imaging noise if alignment with the peak of the Stiles-Crawford function cannot be maintained. Therefore, complete head stabilization by implementation of a bite-bar may be critical to maintain a constant pupil entry position of the OCT beam. Due to depth-dependent sensitivity fall-off, heartbeat and breathing associated axial movements can cause tissue reflectivity to vary by 29% over time, although known methods can be implemented to null these effects. Substantial variations in reflectivity can be caused by variable illumination due to changes in the beam pupil entry position and angle, which can be reduced by an adaptive algorithm based on slope-fitting of optical attenuation in the choriocapillary lamina.
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Affiliation(s)
- Michel M. Teussink
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, P.O. Box 6500 HB,
The Netherlands
| | - Barry Cense
- Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Tochigi, 321-8585,
Japan
| | - Mark J.J.P. van Grinsven
- Diagnostic Image Analysis Group, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, P.O. Box 6500 HB,
The Netherlands
| | - B. Jeroen Klevering
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, P.O. Box 6500 HB,
The Netherlands
| | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, P.O. Box 6500 HB,
The Netherlands
| | - Thomas Theelen
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, P.O. Box 6500 HB,
The Netherlands
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Abstract
Light microscopy plays a key role in biological studies and medical diagnosis. The spatial resolution of conventional optical microscopes is limited to approximately half the wavelength of the illumination light as a result of the diffraction limit. Several approaches-including confocal microscopy, stimulated emission depletion microscopy, stochastic optical reconstruction microscopy, photoactivated localization microscopy, and structured illumination microscopy-have been established to achieve super-resolution imaging. However, none of these methods is suitable for the super-resolution ophthalmoscopy of retinal structures because of laser safety issues and inevitable eye movements. We recently experimentally validated virtually structured detection (VSD) as an alternative strategy to extend the diffraction limit. Without the complexity of structured illumination, VSD provides an easy, low-cost, and phase artifact-free strategy to achieve super-resolution in scanning laser microscopy. In this article we summarize the basic principles of the VSD method, review our demonstrated single-point and line-scan super-resolution systems, and discuss both technical challenges and the potential of VSD-based instrumentation for super-resolution ophthalmoscopy of the retina.
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Affiliation(s)
- Yanan Zhi
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL
| | - Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL
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Yao XC, Li YC. Functional imaging of retinal photoreceptors and inner neurons using stimulus-evoked intrinsic optical signals. Methods Mol Biol 2012; 884:277-85. [PMID: 22688714 PMCID: PMC3644518 DOI: 10.1007/978-1-61779-848-1_20] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Retinal development is a dynamic process both anatomically and functionally. High-resolution imaging and dynamic monitoring of photoreceptors and inner neurons can provide important information regarding the structure and function of the developing retina. In this chapter, we describe intrinsic optical signal (IOS) imaging as a high spatiotemporal resolution method for functional study of living retinal tissues. IOS imaging is based on near infrared (NIR) light detection of stimulus-evoked transient change of inherent optical characteristics of the cells. With no requirement for exogenous biomarkers, IOS imaging is totally noninvasive for functional mapping of stimulus-evoked spatiotemporal dynamics of the photoreceptors and inner retinal neurons.
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Affiliation(s)
- Xin-Cheng Yao
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, USA.
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Zhang QX, Lu RW, Li YG, Yao XC. In vivo confocal imaging of fast intrinsic optical signals correlated with frog retinal activation. OPTICS LETTERS 2011; 36:4692-4. [PMID: 22139286 PMCID: PMC3258673 DOI: 10.1364/ol.36.004692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Using freshly isolated animal retinas, we have conducted a series of experiments to test fast intrinsic optical signals (IOSs) that have time courses comparable to electrophysiological kinetics. In this Letter, we demonstrate the feasibility of in vivo imaging of fast IOSs in intact frogs. A rapid line-scan confocal ophthalmoscope was constructed to achieve high-speed IOS recording. By rejecting out-of-focus background light, the line-scan confocal imager provided the resolution to differentiate individual photoreceptors in vivo. Rapid confocal imaging disclosed robust IOSs with time courses comparable to retinal electroretinogram kinetics. High-resolution IOS images revealed both positive (increasing) and negative (decreasing) light responses, with subcellular complexity.
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Affiliation(s)
- Qiu-Xiang Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Rong-Wen Lu
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Yang-Guo Li
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Xin-Cheng Yao
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
- Vision Science Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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12
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Li YG, Liu L, Amthor F, Yao XC. High-speed line-scan confocal imaging of stimulus-evoked intrinsic optical signals in the retina. OPTICS LETTERS 2010; 35:426-8. [PMID: 20125743 PMCID: PMC2921995 DOI: 10.1364/ol.35.000426] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A rapid line-scan confocal imager was developed for functional imaging of the retina. In this imager, an acousto-optic deflector was employed to produce mechanical vibration- and inertia-free light scanning, and a high-speed (68,000 Hz) linear CCD camera was used to achieve subcellular and submillisecond spatiotemporal resolution imaging. Two imaging modalities, i.e., frame-by-frame and line-by-line recording, were validated for the reflected light detection of intrinsic optical signals (IOSs) in visible light stimulus activated frog retinas. Experimental results indicated that fast IOSs were tightly correlated with retinal stimuli and could track visible light flicker stimulus frequency up to at least 2 Hz.
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Affiliation(s)
- Yang-Guo Li
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Lei Liu
- Department of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Franklin Amthor
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Xin-Cheng Yao
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294
- Corresponding author:
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