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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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Kim TH, Wang B, Lu Y, Son T, Yao X. Functional optical coherence tomography enables in vivo optoretinography of photoreceptor dysfunction due to retinal degeneration. BIOMEDICAL OPTICS EXPRESS 2020; 11:5306-5320. [PMID: 33014616 PMCID: PMC7510876 DOI: 10.1364/boe.399334] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 05/16/2023]
Abstract
Stimulus-evoked intrinsic optical signal (IOS), which occurs almost immediately after the onset of retinal stimulus has been observed in retinal photoreceptors, promises to be a unique biomarker for objective optoretinography (ORG) of photoreceptor function. We report here the first-time in vivo ORG detection of photoreceptor dysfunction due to retinal degeneration. A custom-designed optical coherence tomography (OCT) was employed for longitudinal ORG monitoring of photoreceptor-IOS distortions in retinal degeneration mice. Depth-resolved OCT analysis confirmed the outer segment (OS) as the physical source of the photoreceptor-IOS. Comparative ERG measurement verified the phototransduction activation as the physiological correlator of the photoreceptor-IOS. Histological examination revealed disorganized OS discs, i.e. the pathological origin of the photoreceptor-IOS distortion.
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Affiliation(s)
- Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Taeyoon Son
- 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, 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 PMCID: PMC7400727 DOI: 10.1177/1535370220935406] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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Lu Y, Benedetti J, Yao X. Light-Induced Length Shrinkage of Rod Photoreceptor Outer Segments. Transl Vis Sci Technol 2018; 7:29. [PMID: 30619649 PMCID: PMC6314056 DOI: 10.1167/tvst.7.6.29] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022] Open
Abstract
Purpose This study was designed to verify light-induced outer segment (OS) length shrinkage of rod photoreceptors and to characterize its anatomic source at disc-level resolution. Methods Frog (Rana pipiens) retinas were used for this study. Time-lapse light microscopy of freshly isolated OSs was employed to test transient rod OS changes at 10 ms temporal resolution. Histological light microscopy of dark- and light-adapted retinas was used to confirm light-induced rod OS length changes; and transmission electron microscopy (TEM) was used to quantify light-driven structural perturbation of rod OSs at disc level resolution. Results Time-lapse light microscopy images verified transient length shrinking responses in freshly isolated rod OSs. Histological light microscopy images confirmed reduced rod OS lengths in light-adapted retinas, compared to that of dark-adapted retinas. TEM images disclosed shortened inter-disc distances in light-adapted retinas compared to dark-adapted retinas. Conclusions Light-induced rod OS length shrinkage was confirmed using time-lapse light microscopy of isolated rod OSs and histological light microscopy of dark- and light-adapted retinas. TEM revealed that the rod OS length shrinkage was correlated to the light-driven decrease of the space between individual discs, not the disc thickness itself. Translational Relevance Light-induced transient rod response promises a noninvasive biomarker for early diagnosis of age-related macular degeneration and retinitis pigmentosa, in which the rod photoreceptors are known to be more vulnerable than cone photoreceptors.
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Affiliation(s)
- Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Jacopo Benedetti
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.,Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
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Lu Y, Wang B, Pepperberg DR, Yao X. Stimulus-evoked outer segment changes occur before the hyperpolarization of retinal photoreceptors. BIOMEDICAL OPTICS EXPRESS 2017; 8:38-47. [PMID: 28101399 PMCID: PMC5231306 DOI: 10.1364/boe.8.000038] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/02/2016] [Accepted: 11/09/2016] [Indexed: 05/22/2023]
Abstract
Transient retinal phototropism (TRP) has been predominantly observed in rod photoreceptors activated by oblique visible light stimulation. Dynamic confocal microscopy and optical coherence tomography (OCT) have revealed rod outer segment (ROS) movement as the physical source of TRP. However, the physiological source of ROS movement is still not well understood. In this study, concurrent near-infrared imaging of TRP and electroretinogram (ERG) measurement of retinal electrophysiology revealed that ROS movement occurs before the onset of the ERG a-wave, which is known to reflect the hyperpolarization of retinal photoreceptors. Moreover, substitution of normal superfusing medium with low-sodium medium reversibly blocked the photoreceptor ERG a-wave, but largely preserved the stimulus-evoked ROS movements. Our experimental results and theoretical analysis indicate that early, disc-based stages of the phototransduction cascade, which occur before the hyperpolarization of retinal photoreceptors, contribute to the TRP associated ROS movement.
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Affiliation(s)
- Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Benquan Wang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - David R. Pepperberg
- Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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Zhao X, Thapa D, Wang B, Lu Y, Gai S, Yao X. Stimulus-evoked outer segment changes in rod photoreceptors. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:65006. [PMID: 27334933 PMCID: PMC4917604 DOI: 10.1117/1.jbo.21.6.065006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/01/2016] [Indexed: 05/21/2023]
Abstract
Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.
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Affiliation(s)
- Xiaohui Zhao
- Hebei University, College of Physics Science and Technology, Hebei Key Lab of Optic-Electronic Information Materials, Baoding 071002, China
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
| | - Damber Thapa
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
| | - Benquan Wang
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
| | - Yiming Lu
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
| | - Shaoyan Gai
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois 60607, United States
| | - Xincheng Yao
- Hebei University, College of Physics Science and Technology, Hebei Key Lab of Optic-Electronic Information Materials, Baoding 071002, China
- 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
- Address all correspondence to: Xincheng Yao, E-mail:
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