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Lee S, Choi SS, Meleppat RK, Zawadzki RJ, Doble N. High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmoscope. BIOMEDICAL OPTICS EXPRESS 2024; 15:1815-1830. [PMID: 38495707 PMCID: PMC10942708 DOI: 10.1364/boe.507449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/18/2023] [Accepted: 01/14/2024] [Indexed: 03/19/2024]
Abstract
High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmosocope (AO-pcMLO) is described. It allows for simultaneous confocal and phase contrast imaging with various directional multi-line illumination by using a single 2D camera and a digital micromirror device (DMD). Both vertical and horizontal line illumination directions were tested, for photoreceptor and vascular imaging. The phase contrast imaging provided improved visualization of retinal structures such as cone inner segments, vessel walls and red blood cells with images being acquired at frame rates up to 500 Hz. Blood flow velocities of small vessels (<40 µm in diameter) were measured using kymographs for capillaries and cross-correlation between subsequent images for arterioles or venules. Cardiac-related pulsatile patterns were observed with normal resting heart-beat rate, and instantaneous blood flow velocities from 0.7 to 20 mm/s were measured.
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Affiliation(s)
- Soohyun Lee
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
| | - Stacey S. Choi
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
| | - Ratheesh K. Meleppat
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Robert J. Zawadzki
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Nathan Doble
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
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2
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Bedggood P, Ding Y, Metha A. Changes to the shape, orientation and packing of red cells as a function of retinal capillary size. BIOMEDICAL OPTICS EXPRESS 2024; 15:558-578. [PMID: 38404337 PMCID: PMC10890884 DOI: 10.1364/boe.511093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 02/27/2024]
Abstract
The free diameter of a red blood cell exceeds the lumen diameter of capillaries in the central nervous system, requiring significant deformation of cells. However the deformations undertaken in vivo are not well established due to the difficulty in observing cellular capillary flow in living human tissue. Here, we used high resolution adaptive optics imaging to non-invasively track 17,842 red blood cells in transit through 121 unique capillary segments of diameter 8 µm or less in the retina of 3 healthy human subjects. Within each vessel, a 2D en face profile was generated for the "average cell", whose shape was then inferred in 3D based on the key assumption of a circular capillary cross-section. From this we estimated the average volume, surface area, orientation, and separation between red cells within each capillary tube. Our results showed a network filtration effect, whereby narrower vessels were more likely to contain smaller cells (defined by surface area, which is thought not to vary during a cell's passage through the vascular system). A bivariate linear model showed that for larger cells in narrower vessels: cells re-orient themselves to align with the flow axis, their shape becomes more elongated, there are longer gaps between successive cells, and remarkably, that cell volume is less which implies the ejection of water from cells to facilitate capillary transit. Taken together, these findings suggest that red cells pass through retinal capillaries with some reluctance. A biphasic distribution for cell orientation and separation was evident, indicating a "tipping point" for vessels narrower than approx. 5 µm. This corresponds closely to the typical capillary lumen diameter, and may maximize sensitivity of cellular flow to small changes in diameter. We suggest that the minimization of unnecessary oxygen exchange, and hence of damage via reactive oxygen pathways, may have provided evolutionary pressure to ensure that capillary lumens are generally narrower than red blood cells.
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Affiliation(s)
- Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, 3010, Australia
| | - Yifu Ding
- Department of Optometry and Vision Sciences, The University of Melbourne, 3010, Australia
| | - Andrew Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, 3010, Australia
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3
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Neriyanuri S, Bedggood P, Symons RCA, Metha AB. Validation of an automated method for studying retinal capillary blood flow. BIOMEDICAL OPTICS EXPRESS 2024; 15:802-817. [PMID: 38404315 PMCID: PMC10890846 DOI: 10.1364/boe.504074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/13/2023] [Accepted: 12/28/2023] [Indexed: 02/27/2024]
Abstract
Two major approaches for tracking cellular motion across a range of biological tissues are the manual labelling of cells, and automated analysis of spatiotemporal information represented in a kymograph. Here we compare these two approaches for the measurement of retinal capillary flow, a particularly noisy application due to the low intrinsic contrast of single red blood cells (erythrocytes). Image data were obtained using a flood-illuminated adaptive optics ophthalmoscope at 750 nm, allowing the acquisition of flow information over several cardiac cycles which provided key information in evaluating tracking accuracy. Our results show that in addition to being much faster, the automated method is more accurate in the face of rapid flow and reduced image contrast. This study represents the first validation of commonly used kymograph approaches to capillary flow analysis.
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Affiliation(s)
- Srividya Neriyanuri
- Department of Optometry and Vision Sciences, The University of Melbourne, VIC 3053, Australia
| | - Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, VIC 3053, Australia
| | - R. C. Andrew Symons
- Department of Optometry and Vision Sciences, The University of Melbourne, VIC 3053, Australia
- Department of Surgery, The University of Melbourne, VIC 3053, Australia
- Centre for Eye Research (CERA), VIC 3002, Australia
- Department of Surgery, Alfred Hospital, Monash University, VIC 3004, Australia
| | - Andrew B. Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, VIC 3053, Australia
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4
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Neriyanuri S, Bedggood P, Symons RCA, Metha AB. Flow Heterogeneity and Factors Contributing to the Variability in Retinal Capillary Blood Flow. Invest Ophthalmol Vis Sci 2023; 64:15. [PMID: 37450310 DOI: 10.1167/iovs.64.10.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Purpose Capillary flow plays an important role in the nourishment and maintenance of healthy neural tissue and can be observed directly and non-invasively in the living human retina. Despite their importance, patterns of normal capillary flow are not well understood due to limitations in spatial and temporal resolution of imaging data. Methods Capillary flow characteristics were studied in the retina of three healthy young individuals using a high-resolution adaptive optics ophthalmoscope. Imaging with frame rates of 200 to 300 frames per second was sufficient to capture details of the single-file flow of red blood cells in capillaries over the course of about 3 seconds. Results Erythrocyte velocities were measured from 72 neighboring vessels of the parafoveal capillary network for each subject. We observed strong variability among vessels within a given subject, and even within a given imaged field, across a range of capillary flow parameters including maximum and minimum velocities, pulsatility, abruptness of the systolic peak, and phase of the cardiac cycle. The observed variability was not well explained by "local" factors such as the vessel diameter, tortuosity, length, linear cell density, or hematocrit of the vessel. Within a vessel, a moderate relation between the velocities and hematocrit was noted, suggesting a redistribution of plasma between cells with changes in flow. Conclusions These observations advance our fundamental understanding of normal capillary physiology and raise questions regarding the potential role of network-level effects in explaining the observed flow heterogeneity.
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Affiliation(s)
- Srividya Neriyanuri
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - R C Andrew Symons
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
- Department of Surgery, The University of Melbourne, Parkville, Victoria, Australia
- Centre for Eye Research Australia, East Melbourne, Victoria, Australia
- Department of Surgery, Alfred Hospital, Monash University, Melbourne, Victoria, Australia
| | - Andrew B Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
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Li B, Leng J, Şencan-Eğilmez I, Takase H, Alfadhel MAH, Fu B, Shahidi M, Lo EH, Arai K, Sakadžić S. Differential reductions in the capillary red-blood-cell flux between retina and brain under chronic global hypoperfusion. NEUROPHOTONICS 2023; 10:035001. [PMID: 37323511 PMCID: PMC10266089 DOI: 10.1117/1.nph.10.3.035001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/13/2023] [Accepted: 04/26/2023] [Indexed: 06/17/2023]
Abstract
Significance It has been hypothesized that abnormal microcirculation in the retina might predict the risk of ischemic damages in the brain. Direct comparison between the retinal and the cerebral microcirculation using similar animal preparation and under similar experimental conditions would help test this hypothesis. Aim We investigated capillary red-blood-cell (RBC) flux changes under controlled conditions and bilateral-carotid-artery-stenosis (BCAS)-induced hypoperfusion, and then compared them with our previous measurements performed in the brain. Approach We measured capillary RBC flux in mouse retina with two-photon microscopy using a fluorescence-labeled RBC-passage approach. Key physiological parameters were monitored during experiments to ensure stable physiology. Results We found that under the controlled conditions, capillary RBC flux in the retina was much higher than in the brain (i.e., cerebral cortical gray matter and subcortical white matter), and that BCAS induced a much larger decrease in capillary RBC flux in the retina than in the brain. Conclusions We demonstrated a two-photon microscopy-based technique to efficiently measure capillary RBC flux in the retina. Since cerebral subcortical white matter often exhibits early pathological developments due to global hypoperfusion, our results suggest that retinal microcirculation may be utilized as an early marker of brain diseases involving global hypoperfusion.
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Affiliation(s)
- Baoqiang Li
- Chinese Academy of Sciences, Shenzhen Institute of Advanced Technology, Brain Cognition and Brain Disease Institute; Shenzhen Fundamental Research Institutions, Shenzhen–Hong Kong Institute of Brain Science, Shenzhen, Guangdong, China
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Ji Leng
- Chinese Academy of Sciences, Shenzhen Institute of Advanced Technology, Brain Cognition and Brain Disease Institute; Shenzhen Fundamental Research Institutions, Shenzhen–Hong Kong Institute of Brain Science, Shenzhen, Guangdong, China
| | - Ikbal Şencan-Eğilmez
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Hajime Takase
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Mohammed Ali H. Alfadhel
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Buyin Fu
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
| | - Mahnaz Shahidi
- University of Southern California, Department of Ophthalmology, Los Angeles, California, United States
| | - Eng H. Lo
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Ken Arai
- Harvard Medical School, Massachusetts General Hospital, Department of Radiology, Charlestown, Massachusetts, United States
- Harvard Medical School, Massachusetts General Hospital, Department of Neurology, Charlestown, Massachusetts, United States
| | - Sava Sakadžić
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States
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6
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Hwang Y, Won J, Yaghy A, Takahashi H, Girgis JM, Lam K, Chen S, Moult EM, Ploner SB, Maier A, Waheed NK, Fujimoto JG. Retinal blood flow speed quantification at the capillary level using temporal autocorrelation fitting OCTA [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:2658-2677. [PMID: 37342704 PMCID: PMC10278638 DOI: 10.1364/boe.488103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/23/2023] [Accepted: 04/29/2023] [Indexed: 06/23/2023]
Abstract
Optical coherence tomography angiography (OCTA) can visualize vasculature structures, but provides limited information about blood flow speed. Here, we present a second generation variable interscan time analysis (VISTA) OCTA, which evaluates a quantitative surrogate marker for blood flow speed in vasculature. At the capillary level, spatially compiled OCTA and a simple temporal autocorrelation model, ρ(τ) = exp(-ατ), were used to evaluate a temporal autocorrelation decay constant, α, as the blood flow speed marker. A 600 kHz A-scan rate swept-source OCT prototype instrument provides short interscan time OCTA and fine A-scan spacing acquisition, while maintaining multi mm2 field of views for human retinal imaging. We demonstrate the cardiac pulsatility and assess repeatability of α measured with VISTA. We show different α for different retinal capillary plexuses in healthy eyes and present representative VISTA OCTA in eyes with diabetic retinopathy.
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Affiliation(s)
- Yunchan Hwang
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jungeun Won
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Antonio Yaghy
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - Hiroyuki Takahashi
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | | | - Kenneth Lam
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - Siyu Chen
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Eric M. Moult
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stefan B. Ploner
- Pattern Recognition Lab, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Maier
- Pattern Recognition Lab, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nadia K. Waheed
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - James G. Fujimoto
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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7
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Liu R, Wang X, Hoshi S, Zhang Y. High-speed measurement of retinal arterial blood flow in the living human eye with adaptive optics ophthalmoscopy. OPTICS LETTERS 2023; 48:1994-1997. [PMID: 37058625 DOI: 10.1364/ol.480896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
We present a technique to measure the rapid blood velocity in large retinal vessels with high spatiotemporal resolution. Red blood cell motion traces in the vessels were non-invasively imaged using an adaptive optics near-confocal scanning ophthalmoscope at a frame rate of 200 fps. We developed software to measure blood velocity automatically. We demonstrated the ability to measure the spatiotemporal profiles of the pulsatile blood flow with a maximum velocity of 95-156 mm/s in retinal arterioles with a diameter >100 µm. High-speed and high-resolution imaging increased the dynamic range, enhanced sensitivity, and improved the accuracy when studying retinal hemodynamics.
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8
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Bedggood P, Ding Y, Metha A. Measuring red blood cell shape in the human retina. OPTICS LETTERS 2023; 48:1554-1557. [PMID: 37221708 DOI: 10.1364/ol.483062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/11/2023] [Indexed: 05/25/2023]
Abstract
The free diameter of a red blood cell generally exceeds the lumen diameter of capillaries in the central nervous system, requiring significant cellular deformation. However, the deformations undertaken are not well established under natural conditions due to the difficulty in observing corpuscular flow in vivo. Here we describe a novel, to the best of our knowledge, method to noninvasively study the shape of red blood cells as they traverse the narrow capillary networks of the living human retina, using high-speed adaptive optics. One hundred and twenty-three capillary vessels were analyzed in three healthy subjects. For each capillary, image data were motion-compensated and then averaged over time to reveal the appearance of the blood column. Data from hundreds of red blood cells were used to profile the average cell in each vessel. Diverse cellular geometries were observed across lumens ranging from 3.2 to 8.4 µm in diameter. As capillaries narrowed, cells transitioned from rounder to more elongated shapes and from being counter-aligned to aligned with the axis of flow. Remarkably, in many vessels the red blood cells maintained an oblique orientation relative to the axis of flow.
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9
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Williams DR, Burns SA, Miller DT, Roorda A. Evolution of adaptive optics retinal imaging [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:1307-1338. [PMID: 36950228 PMCID: PMC10026580 DOI: 10.1364/boe.485371] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 02/02/2023] [Indexed: 05/02/2023]
Abstract
This review describes the progress that has been achieved since adaptive optics (AO) was incorporated into the ophthalmoscope a quarter of a century ago, transforming our ability to image the retina at a cellular spatial scale inside the living eye. The review starts with a comprehensive tabulation of AO papers in the field and then describes the technological advances that have occurred, notably through combining AO with other imaging modalities including confocal, fluorescence, phase contrast, and optical coherence tomography. These advances have made possible many scientific discoveries from the first maps of the topography of the trichromatic cone mosaic to exquisitely sensitive measures of optical and structural changes in photoreceptors in response to light. The future evolution of this technology is poised to offer an increasing array of tools to measure and monitor in vivo retinal structure and function with improved resolution and control.
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Affiliation(s)
- David R. Williams
- The Institute of Optics and the Center for
Visual Science, University of Rochester,
Rochester NY, USA
| | - Stephen A. Burns
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Donald T. Miller
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and
Vision Science, University of California at Berkeley, Berkeley CA, USA
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10
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Lai WF, Zhang D, Wong WT. Design of erythrocyte-derived carriers for bioimaging applications. Trends Biotechnol 2023; 41:228-241. [PMID: 36031485 DOI: 10.1016/j.tibtech.2022.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/01/2022] [Accepted: 07/25/2022] [Indexed: 01/24/2023]
Abstract
Erythrocytes are physiological entities that have been exploited in both preclinical and clinical trials for the delivery of exogenous agents. Over the years, diverse erythrocyte-derived carriers (ECs) have been developed with related patents granted for industrial and commercial purposes. However, most ECs have only been exploited for drug delivery. Serious discussions regarding their applications in imaging are scarce. This article reviews the role of ECs in enhancing imaging efficiency and subsequently delineates strategies for engineering and optimising their preclinical and clinical performance. With a snapshot of the latest developments and use of ECs in imaging, directions to streamline the clinical translation of related technologies can be attained for future research.
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Affiliation(s)
- Wing-Fu Lai
- Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China; Department of Urology, Zhejiang Provincial People's Hospital, Hangzhou Medical College, Zhejiang 310012, China.
| | - Dahong Zhang
- Department of Urology, Zhejiang Provincial People's Hospital, Hangzhou Medical College, Zhejiang 310012, China
| | - Wing-Tak Wong
- Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
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11
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Morgan JIW, Chui TYP, Grieve K. Twenty-five years of clinical applications using adaptive optics ophthalmoscopy [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:387-428. [PMID: 36698659 PMCID: PMC9841996 DOI: 10.1364/boe.472274] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/22/2022] [Accepted: 11/27/2022] [Indexed: 05/02/2023]
Abstract
Twenty-five years ago, adaptive optics (AO) was combined with fundus photography, thereby initiating a new era in the field of ophthalmic imaging. Since that time, clinical applications of AO ophthalmoscopy to investigate visual system structure and function in both health and disease abound. To date, AO ophthalmoscopy has enabled visualization of most cell types in the retina, offered insight into retinal and systemic disease pathogenesis, and been integrated into clinical trials. This article reviews clinical applications of AO ophthalmoscopy and addresses remaining challenges for AO ophthalmoscopy to become fully integrated into standard ophthalmic care.
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Affiliation(s)
- Jessica I. W. Morgan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Contributed equally
| | - Toco Y. P. Chui
- Department of Ophthalmology, The New York Eye and Ear Infirmary of Mount Sinai, New York, NY 10003, USA
- Contributed equally
| | - Kate Grieve
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, and CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, F-75012 Paris, France
- Contributed equally
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12
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Li J, Wang D, Pottenburgh J, Bower AJ, Asanad S, Lai EW, Simon C, Im L, Huryn LA, Tao Y, Tam J, Saeedi OJ. Visualization of erythrocyte stasis in the living human eye in health and disease. iScience 2022; 26:105755. [PMID: 36594026 PMCID: PMC9803835 DOI: 10.1016/j.isci.2022.105755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/25/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
Blood cells trapped in stasis have been reported within the microcirculation, but their relevance to health and disease has not been established. In this study, we introduce an in vivo imaging approach that reveals the presence of a previously-unknown pool of erythrocytes in stasis, located within capillary segments of the CNS, and present in 100% of subjects imaged. These results provide a key insight that blood cells pause as they travel through the choroidal microvasculature, a vascular structure that boasts the highest blood flow of any tissue in the body. Demonstration of clinical utility using deep learning reveals that erythrocyte stasis is altered in glaucoma, indicating the possibility of more widespread changes in choroidal microvascular than previously realized. The ability to monitor the choroidal microvasculature at the single cell level may lead to novel strategies for tracking microvascular health in glaucoma, age-related macular degeneration, and other neurodegenerative diseases.
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Affiliation(s)
- Joanne Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Dongyi Wang
- Bioimaging and Machine Vision Laboratory, Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
| | - Jessica Pottenburgh
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrew J. Bower
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Samuel Asanad
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eric W. Lai
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Caroline Simon
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lily Im
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Laryssa A. Huryn
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yang Tao
- Bioimaging and Machine Vision Laboratory, Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Osamah J. Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA,Corresponding author
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13
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Czaja B, de Bouter J, Heisler M, Závodszky G, Karst S, Sarunic M, Maberley D, Hoekstra A. The effect of stiffened diabetic red blood cells on wall shear stress in a reconstructed 3D microaneurysm. Comput Methods Biomech Biomed Engin 2022; 25:1691-1709. [PMID: 35199620 DOI: 10.1080/10255842.2022.2034794] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Blood flow within the vasculature of the retina has been found to influence the progression of diabetic retinopathy. In this research cell resolved blood flow simulations are used to study the pulsatile flow of whole blood through a segmented retinal microaneurysm. Images were collected using adaptive optics optical coherence tomography of the retina of a patient with diabetic retinopathy, and a sidewall (sacciform) microaneurysm was segmented from the volumetric data. The original microaneurysm neck width was varied to produce two additional aneurysm geometries in order to probe the influence of neck width on the transport of red blood cells and platelets into the aneurysm. Red blood cell membrane stiffness was also increased to resolve the impact of rigid red blood cells, as a result of diabetes, in blood flow. Wall shear stress and wall shear stress gradients were calculated throughout the aneurysm domains, and the quantification of the influence of the red blood cells is presented. Average wall shear stress and wall shear stress gradients increased due to the increase of red blood cell membrane stiffness. Stiffened red blood cells were also found to induce higher local wall shear stress and wall shear stress gradients as they passed through the leading and draining parental vessels. Stiffened red blood cells were found to penetrate the aneurysm sac more than healthy red blood cells, as well as decreasing the margination of platelets to the vessel walls of the parental vessel, which caused a decrease in platelet penetration into the aneurysm sac.
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Affiliation(s)
- Benjamin Czaja
- Computational Science Lab, Faculty of Science, Institute for Informatics, University of Amsterdam, Amsterdam, Netherlands
| | - Jonathan de Bouter
- Computational Science Lab, Faculty of Science, Institute for Informatics, University of Amsterdam, Amsterdam, Netherlands
| | - Morgan Heisler
- School of Engineering Science, Faculty of Applied Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Gábor Závodszky
- Computational Science Lab, Faculty of Science, Institute for Informatics, University of Amsterdam, Amsterdam, Netherlands.,Department of Hydrodynamic Systems, Budapest University of Technology and Economics, Budapest, Hungary
| | - Sonja Karst
- Department of Ophthalmology and Optometry, Medical University Vienna, Vienna, Austria
| | - Marinko Sarunic
- School of Engineering Science, Faculty of Applied Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - David Maberley
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Alfons Hoekstra
- Computational Science Lab, Faculty of Science, Institute for Informatics, University of Amsterdam, Amsterdam, Netherlands
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14
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Dholakia KY, Guevara-Torres A, Feng G, Power D, Schallek J. In Vivo Capillary Structure and Blood Cell Flux in the Normal and Diabetic Mouse Eye. Invest Ophthalmol Vis Sci 2022; 63:18. [PMID: 35138346 PMCID: PMC8842443 DOI: 10.1167/iovs.63.2.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Purpose To characterize the early structural and functional changes in the retinal microvasculature in response to hyperglycemia in the Ins2Akita mouse. Methods A custom phase-contrast adaptive optics scanning light ophthalmoscope was used to image retinal capillaries of 9 Ins2Akita positive (hyperglycemic) and 9 Ins2Akita negative (euglycemic) mice from postnatal weeks 5 to 18. A 15 kHz point scan was used to image capillaries and measure red blood cell flux at biweekly intervals; measurements were performed manually. Retinal thickness and fundus photos were captured monthly using a commercial scanning laser ophthalmoscope/optical coherence tomography. Retinal thickness was calculated using a custom algorithm. Blood glucose and weight were tracked throughout the duration of the study. Results Elevated blood glucose (>250 mg/dL) was observed at 4 to 5 weeks of age in Ins2Akita mice and remained elevated throughout the study, whereas euglycemic littermates maintained normal glucose levels. There was no significant difference in red blood cell flux, capillary anatomy, lumen diameter, or occurrence of stalled capillaries between hyperglycemic and euglycemic mice between postnatal weeks 5 and 18. Hyperglycemic mice had a thinner retina than euglycemic littermates (p < 0.001), but retinal thickness did not change with duration of hyperglycemia despite glucose levels that were more than twice times normal. Conclusions In early stages of hyperglycemia, retinal microvasculature structure (lumen diameter, capillary anatomy) and function (red blood cell flux, capillary perfusion) were not impaired despite 3 months of chronically elevated blood glucose. These findings suggest that hyperglycemia alone for 3 months does not alter capillary structure or function in profoundly hyperglycemic mice.
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Affiliation(s)
- Kosha Y Dholakia
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Andres Guevara-Torres
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Guanping Feng
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States.,Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Derek Power
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, Rochester, New York, United States.,Department of Neuroscience, University of Rochester, Rochester, New York, United States
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15
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Li H, Deng Y, Sampani K, Cai S, Li Z, Sun JK, Karniadakis GE. Computational investigation of blood cell transport in retinal microaneurysms. PLoS Comput Biol 2022; 18:e1009728. [PMID: 34986147 PMCID: PMC8730408 DOI: 10.1371/journal.pcbi.1009728] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 12/07/2021] [Indexed: 12/15/2022] Open
Abstract
Microaneurysms (MAs) are one of the earliest clinically visible signs of diabetic retinopathy (DR). MA leakage or rupture may precipitate local pathology in the surrounding neural retina that impacts visual function. Thrombosis in MAs may affect their turnover time, an indicator associated with visual and anatomic outcomes in the diabetic eyes. In this work, we perform computational modeling of blood flow in microchannels containing various MAs to investigate the pathologies of MAs in DR. The particle-based model employed in this study can explicitly represent red blood cells (RBCs) and platelets as well as their interaction in the blood flow, a process that is very difficult to observe in vivo. Our simulations illustrate that while the main blood flow from the parent vessels can perfuse the entire lumen of MAs with small body-to-neck ratio (BNR), it can only perfuse part of the lumen in MAs with large BNR, particularly at a low hematocrit level, leading to possible hypoxic conditions inside MAs. We also quantify the impacts of the size of MAs, blood flow velocity, hematocrit and RBC stiffness and adhesion on the likelihood of platelets entering MAs as well as their residence time inside, two factors that are thought to be associated with thrombus formation in MAs. Our results show that enlarged MA size, increased blood velocity and hematocrit in the parent vessel of MAs as well as the RBC-RBC adhesion promote the migration of platelets into MAs and also prolong their residence time, thereby increasing the propensity of thrombosis within MAs. Overall, our work suggests that computational simulations using particle-based models can help to understand the microvascular pathology pertaining to MAs in DR and provide insights to stimulate and steer new experimental and computational studies in this area.
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Affiliation(s)
- He Li
- School of Engineering, Brown University, Providence, Rhode Island, United States of America
| | - Yixiang Deng
- School of Engineering, Brown University, Providence, Rhode Island, United States of America
| | - Konstantina Sampani
- Beetham Eye Institute, Joslin Diabetes Center, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shengze Cai
- Division of Applied Mathematics, Brown University, Providence, Rhode Island, United States of America
| | - Zhen Li
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, United States of America
| | - Jennifer K. Sun
- Beetham Eye Institute, Joslin Diabetes Center, Boston, Massachusetts, United States of America
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - George E. Karniadakis
- School of Engineering, Brown University, Providence, Rhode Island, United States of America
- Division of Applied Mathematics, Brown University, Providence, Rhode Island, United States of America
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16
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Dessalles CA, Ramón-Lozano C, Babataheri A, Barakat AI. Luminal flow actuation generates coupled shear and strain in a microvessel-on-chip. Biofabrication 2021; 14. [PMID: 34592728 DOI: 10.1088/1758-5090/ac2baa] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/30/2021] [Indexed: 12/12/2022]
Abstract
In the microvasculature, blood flow-derived forces are key regulators of vascular structure and function. Consequently, the development of hydrogel-based microvessel-on-chip systems that strive to mimic thein vivocellular organization and mechanical environment has received great attention in recent years. However, despite intensive efforts, current microvessel-on-chip systems suffer from several limitations, most notably failure to produce physiologically relevant wall strain levels. In this study, a novel microvessel-on-chip based on the templating technique and using luminal flow actuation to generate physiologically relevant levels of wall shear stress and circumferential stretch is presented. Normal forces induced by the luminal pressure compress the surrounding soft collagen hydrogel, dilate the channel, and create large circumferential strain. The fluid pressure gradient in the system drives flow forward and generates realistic pulsatile wall shear stresses. Rigorous characterization of the system reveals the crucial role played by the poroelastic behavior of the hydrogel in determining the magnitudes of the wall shear stress and strain. The experimental measurements are combined with an analytical model of flow in both the lumen and the porous hydrogel to provide an exceptionally versatile user manual for an application-based choice of parameters in microvessels-on-chip. This unique strategy of flow actuation adds a dimension to the capabilities of microvessel-on-chip systems and provides a more general framework for improving hydrogel-basedin vitroengineered platforms.
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Affiliation(s)
- Claire A Dessalles
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Clara Ramón-Lozano
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Avin Babataheri
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
| | - Abdul I Barakat
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120 Palaiseau, France
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17
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Bedggood P, Metha A. Direct measurement of pulse wave propagation in capillaries of the human retina. OPTICS LETTERS 2021; 46:4450-4453. [PMID: 34525019 DOI: 10.1364/ol.434454] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
With each contraction of the heart's left ventricle, a pulse pressure wave surges into the aorta and propagates throughout the vascular tree. The pulse wave drives blood flow forward. Its passage is complex, but it passes more quickly through non-compliant, or stiff, vessels, providing an important signpost of cardiovascular disease. The transparent media of the eye allow direct and non-invasive measurement of this phenomenon within the microvasculature of neural tissue. However, previous estimates differ over three orders of magnitude. Here, we used high spatiotemporal resolution adaptive optics imaging to directly track the pulse wave within individual retinal capillaries in three human subjects. Across 74 unique capillary segments, pulse wave velocity averaged 6.4±0.5mm/sec (mean±SEM). There was large variation between vessels; the slowest pulse wave was at most 0.8 mm/sec and the fastest at least 17.6 mm/sec. In 44% of vessels, the pulse wave traveled upstream, in the opposite direction to flow, suggesting wave reflection from downstream collecting junctions.
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18
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Abstract
Advances in retinal imaging are enabling researchers and clinicians to make precise noninvasive measurements of the retinal vasculature in vivo. This includes measurements of capillary blood flow, the regulation of blood flow, and the delivery of oxygen, as well as mapping of perfused blood vessels. These advances promise to revolutionize our understanding of vascular regulation, as well as the management of retinal vascular diseases. This review provides an overview of imaging and optical measurements of the function and structure of the ocular vasculature. We include general characteristics of vascular systems with an emphasis on the eye and its unique status. The functions of vascular systems are discussed, along with physical principles governing flow and its regulation. Vascular measurement techniques based on reflectance and absorption are briefly introduced, emphasizing ways of generating contrast. One of the prime ways to enhance contrast within vessels is to use techniques sensitive to the motion of cells, allowing precise measurements of perfusion and blood velocity. Finally, we provide a brief introduction to retinal vascular diseases.
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Affiliation(s)
- Stephen A Burns
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
| | - Ann E Elsner
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
| | - Thomas J Gast
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
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19
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Gu B, Sarraf D, Ip M, Sadda SR, Zhang Y. In vivo measurement of the lineal density of red blood cells in human retinal capillaries using high-speed adaptive optics ophthalmoscopy. OPTICS LETTERS 2021; 46:3392-3395. [PMID: 34264221 DOI: 10.1364/ol.428538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 06/12/2021] [Indexed: 05/18/2023]
Abstract
We present an automated method for measuring the lineal density of red blood cells (RBCs) in human retinal capillaries using adaptive optics near-confocal ophthalmoscopy (AONCO). The spatiotemporal traces of RBCs flowing in retinal capillaries were extracted from AONCO images, enhanced using the Gabor filter, the vesselness filter, and the Hough transform. A total of 43 capillary segments (each 50 µm long) were analyzed in 12 eyes of 12 subjects, and the measurement error of the automated method was 0.09 cell over 50 µm compared with results obtained by manual counting. Our method provides a tool for assessing RBC spatial distribution in retinal capillaries.
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20
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Affiliation(s)
- Michael D Twa
- Editor in Chief, University of Houston College of Optometry, Houston, TX
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21
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Bedggood P, Metha A. Adaptive optics imaging of the retinal microvasculature. Clin Exp Optom 2021; 103:112-122. [DOI: 10.1111/cxo.12988] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/17/2019] [Accepted: 09/20/2019] [Indexed: 12/31/2022] Open
Affiliation(s)
- Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia,
| | - Andrew Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia,
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22
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Dessalles CA, Babataheri A, Barakat AI. Pericyte mechanics and mechanobiology. J Cell Sci 2021; 134:134/6/jcs240226. [PMID: 33753399 DOI: 10.1242/jcs.240226] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pericytes are mural cells of the microvasculature, recognized by their thin processes and protruding cell body. Pericytes wrap around endothelial cells and play a central role in regulating various endothelial functions, including angiogenesis and inflammation. They also serve as a vascular support and regulate blood flow by contraction. Prior reviews have examined pericyte biological functions and biochemical signaling pathways. In this Review, we focus on the role of mechanics and mechanobiology in regulating pericyte function. After an overview of the morphology and structure of pericytes, we describe their interactions with both the basement membrane and endothelial cells. We then turn our attention to biophysical considerations, and describe contractile forces generated by pericytes, mechanical forces exerted on pericytes, and pericyte responses to these forces. Finally, we discuss 2D and 3D engineered in vitro models for studying pericyte mechano-responsiveness and underscore the need for more evolved models that provide improved understanding of pericyte function and dysfunction.
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Affiliation(s)
- Claire A Dessalles
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120, Palaiseau, France
| | - Avin Babataheri
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120, Palaiseau, France
| | - Abdul I Barakat
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, 91120, Palaiseau, France
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23
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Zhang X, Chia E, Fan X, Ping J. Flow-sensory contact electrification of graphene. Nat Commun 2021; 12:1755. [PMID: 33741935 PMCID: PMC7979811 DOI: 10.1038/s41467-021-21974-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/17/2021] [Indexed: 11/10/2022] Open
Abstract
All-electronic interrogation of biofluid flow velocity by electrical nanosensors incorporated in ultra-low-power or self-sustained systems offers the promise of enabling multifarious emerging research and applications. However, existing nano-based electrical flow sensing technologies remain lacking in precision and stability and are typically only applicable to simple aqueous solutions or liquid/gas dual-phase mixtures, making them unsuitable for monitoring low-flow (~micrometer/second) yet important characteristics of continuous biofluids (such as hemorheological behaviors in microcirculation). Here, we show that monolayer-graphene single microelectrodes harvesting charge from continuous aqueous flow provide an effective flow sensing strategy that delivers key performance metrics orders of magnitude higher than other electrical approaches. In particular, over six-months stability and sub-micrometer/second resolution in real-time quantification of whole-blood flows with multiscale amplitude-temporal characteristics are obtained in a microfluidic chip.
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Affiliation(s)
- Xiaoyu Zhang
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA, USA
| | - Eric Chia
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA, USA
| | - Xiao Fan
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA, USA
| | - Jinglei Ping
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA, USA.
- Institute for Applied Life Sciences, University of Massachusetts Amherst, Amherst, MA, USA.
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24
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Forrester JV, Kuffova L, Delibegovic M. The Role of Inflammation in Diabetic Retinopathy. Front Immunol 2020; 11:583687. [PMID: 33240272 PMCID: PMC7677305 DOI: 10.3389/fimmu.2020.583687] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/21/2020] [Indexed: 12/14/2022] Open
Abstract
Inflammation is central to pathogenic processes in diabetes mellitus and the metabolic syndrome and particularly implicates innate immunity in the development of complications. Inflammation is a primary event in Type 1 diabetes where infectious (viral) and/or autoimmune processes initiate disease; in contrast, chronic inflammation is typical in Type 2 diabetes and is considered a sequel to increasing insulin resistance and disturbed glucose metabolism. Diabetic retinopathy (DR) is perceived as a vascular and neurodegenerative disease which occurs after some years of poorly controlled diabetes. However, many of the clinical features of DR are late events and reflect the nature of the retinal architecture and its cellular composition. Retinal microvascular disease is, in fact, an early event pathogenetically, induced by low grade, persistent leukocyte activation which causes repeated episodes of capillary occlusion and, progressive, attritional retinal ischemia. The later, overt clinical signs of DR are a consequence of the retinal ischemia. Metabolic dysregulation involving both lipid and glucose metabolism may lead to leukocyte activation. On a molecular level, we have shown that macrophage-restricted protein tyrosine phosphatase 1B (PTP1B) is a key regulator of inflammation in the metabolic syndrome involving insulin resistance and it is possible that PTP1B dysregulation may underlie retinal microvascular disease. We have also shown that adherent CCR5+CD11b+ monocyte macrophages appear to be selectively involved in retinal microvascular occlusion. In this review, we discuss the relationship between early leukocyte activation and the later features of DR, common pathogenetic processes between diabetic microvascular disease and other vascular retinopathies, the mechanisms whereby leukocyte activation is induced in hyperglycemia and dyslipidemia, the signaling mechanisms involved in diabetic microvascular disease, and possible interventions which may prevent these retinopathies. We also address a possible role for adaptive immunity in DR. Although significant improvements in treatment of DR have been made with intravitreal anti-VEGF therapy, a sizeable proportion of patients, particularly with sight-threatening macular edema, fail to respond. Alternative therapies targeting inflammatory processes may offer an advantage.
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Affiliation(s)
- John V Forrester
- Institute of Medical Sciences, University of Aberdeen, Scotland, United Kingdom
| | - Lucia Kuffova
- Institute of Medical Sciences, University of Aberdeen, Scotland, United Kingdom.,Eye Clinic, Aberdeen Royal Infirmary, Aberdeen, United Kingdom
| | - Mirela Delibegovic
- Institute of Medical Sciences, University of Aberdeen, Scotland, United Kingdom
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25
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Wynne N, Carroll J, Duncan JL. Promises and pitfalls of evaluating photoreceptor-based retinal disease with adaptive optics scanning light ophthalmoscopy (AOSLO). Prog Retin Eye Res 2020; 83:100920. [PMID: 33161127 DOI: 10.1016/j.preteyeres.2020.100920] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows visualization of the living human retina with exquisite single-cell resolution. This technology has improved our understanding of normal retinal structure and revealed pathophysiological details of a number of retinal diseases. Despite the remarkable capabilities of AOSLO, it has not seen the widespread commercial adoption and mainstream clinical success of other modalities developed in a similar time frame. Nevertheless, continued advancements in AOSLO hardware and software have expanded use to a broader range of patients. Current devices enable imaging of a number of different retinal cell types, with recent improvements in stimulus and detection schemes enabling monitoring of retinal function, microscopic structural changes, and even subcellular activity. This has positioned AOSLO for use in clinical trials, primarily as exploratory outcome measures or biomarkers that can be used to monitor disease progression or therapeutic response. AOSLO metrics could facilitate patient selection for such trials, to refine inclusion criteria or to guide the choice of therapy, depending on the presence, absence, or functional viability of specific cell types. Here we explore the potential of AOSLO retinal imaging by reviewing clinical applications as well as some of the pitfalls and barriers to more widespread clinical adoption.
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Affiliation(s)
- Niamh Wynne
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA, USA.
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26
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Full-field flicker evoked changes in parafoveal retinal blood flow. Sci Rep 2020; 10:16051. [PMID: 32994535 PMCID: PMC7524838 DOI: 10.1038/s41598-020-73032-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022] Open
Abstract
When retinal activity is increased by exposure to dynamic visual stimuli, blood vessels dilate and the flow of blood within vessels increases to meet the oxygen and glucose demands of the neurons. This relationship is termed ‘neurovascular coupling’ and it is critical for regulating control of the human retinal vasculature. In this study, we used a recently developed technique based on a dual-beam adaptive optics scanning laser ophthalmoscope to measure changes in red blood cell velocities, vessel diameter, and flow in interconnected small parafoveal retinal vessels (< 50 µm) of nine healthy participants. A full-field flicker stimulus was presented onto the retina to induce a vascular response to neural activity. Flicker stimulation increased blood velocity, vessel diameter, and therefore flow in arterioles, capillaries, and venules in all nine subjects. ANOVA and post hoc t-test showed significant increases in velocity and flow in arterioles and venules. These measurements indicate that the mechanism of neurovascular coupling systematically affects the vascular response in small retinal vessels in order to maintain hemodynamic regulation in the retina when exposed to visual stimulation, in our case flicker. Our findings may provide insight into future investigations on the impairments of neurovascular coupling from vascular diseases such as diabetic mellitus.
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27
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Asanad S, Mohammed I, Sadun AA, Saeedi OJ. OCTA in neurodegenerative optic neuropathies: emerging biomarkers at the eye-brain interface. Ther Adv Ophthalmol 2020; 12:2515841420950508. [PMID: 32923939 PMCID: PMC7457690 DOI: 10.1177/2515841420950508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 07/13/2020] [Indexed: 12/22/2022] Open
Abstract
OCTA imaging in optic neuropathies.
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Affiliation(s)
- Samuel Asanad
- Department of Ophthalmology and Visual Sciences, University of Maryland Eye Associates, University of Maryland Medical Center and University of Maryland School of Medicine, 419 W. Redwood St., Baltimore, MD 21201, USA
| | - Isa Mohammed
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alfredo A Sadun
- Doheny Eye Center, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Osamah J Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
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28
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Structural imaging of the retina in psychosis spectrum disorders: current status and perspectives. Curr Opin Psychiatry 2020; 33:476-483. [PMID: 32639357 DOI: 10.1097/yco.0000000000000624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Structural changes of the retina in schizophrenia and other psychotic disorders seem plausible as these conditions are accompanied by widespread morphological abnormalities of the brain. Advances in structural retinal imaging have led to the possibility of precise quantification of individual retinal layers, using optical coherence tomography (OCT) scanners. RECENT FINDINGS The aggregation of information related to OCT findings in schizophrenia has resulted in three metaanalyses, which are currently described. Areas where retinal changes were reported include retinal nerve fiber layer (RNFL), ganglion cell layer complex (GCC), macular volume, and macular thickness, but findings on affected retinal segments vary to some extent across studies. Discrepancies in individual studies could be because of small samples, heterogeneity within schizophrenia (phase of the illness, illness duration, predominant symptomatology), inconsistent reporting of antipsychotic therapy, insufficient control of confounding variables (somatic comorbidities, smoking, and so on), and use of the different types of OCT scanners. SUMMARY Exploration of potential disturbances in retinal architecture could provide new insights into neuronal changes associated with psychosis spectrum disorders, with potential to elucidate the nature and timing of developmental, progressive, inflammatory, and degenerative aspects of neuropathology and pathophysiology, and to assist with characterizing heterogeneity and facilitating personalized treatment approaches.
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29
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Bedggood P, Metha A. Recovering the appearance of the capillary blood column from under-sampled flow data. OPTICS LETTERS 2020; 45:4320-4323. [PMID: 32735288 DOI: 10.1364/ol.398168] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
The regular spacing of cells in capillary flow results in spurious cell trajectories if the sampling rate is too low. This makes it difficult to identify cells, even if the velocity is known. Here, we demonstrate a software method to overcome this problem and validate it using high frame rate data with known velocity, which is downsampled to produce aliasing. The method assumes high spatial sampling, constant velocity over short epochs, and an incompressible blood column. Data in successive frames are shifted along the capillary tube axis according to the flow velocity, faithfully rendering cells and plasma. The velocity estimate, required as input to this procedure, can be obtained from either a) the blind optimization of a simple heuristic, or b) a recently proposed velocimetry algorithm, which appears to extend the aliasing limit.
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30
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Silverstein SM, Demmin DL, Schallek JB, Fradkin SI. Measures of Retinal Structure and Function as Biomarkers in Neurology and Psychiatry. Biomark Neuropsychiatry 2020. [DOI: 10.1016/j.bionps.2020.100018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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31
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Lan G, Gu B, Larin KV, Twa MD. Clinical Corneal Optical Coherence Elastography Measurement Precision: Effect of Heartbeat and Respiration. Transl Vis Sci Technol 2020; 9:3. [PMID: 32821475 PMCID: PMC7401940 DOI: 10.1167/tvst.9.5.3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/30/2019] [Indexed: 01/29/2023] Open
Abstract
Purpose Normal physiological movements (e.g., respiration and heartbeat) induce eye motions during clinical measurements of human corneal biomechanical properties using optical coherence elastography (OCE). We quantified the effects of respiratory and cardiac-induced eye motions on clinical corneal OCE measurement precision and repeatability. Methods Corneal OCE was performed using low-force, micro-air-pulse tissue stimulation and high-resolution phase-sensitive optical coherence tomography (OCT) imaging. Axial surface displacements of the corneal apex were measured (M-mode) at a 70-kHz sampling rate and three different stimulation pressures (20-60 Pa). Simultaneously, the axial corneal position was tracked with structural OCT imaging, while the heartrate and respiration were monitored over a 90 second period. Results Respiratory- and cardiac-induced eye motions have distinctly lower frequency (0.1-1 Hz) and much greater amplitude (up to ± 50 µm movements) than air-pulse-induced corneal tissue deformations (∼250 Hz, <1 µm). The corneal displacements induced during OCE measurements in vivo were -0.41 ± 0.06 µm (n = 22 measurements, coefficient of variation [CV]: 14.6%) and -0.44 ± 0.07 µm (n = 50 measurements, CV: 15.9%), respectively, from two human subjects at 40 Pa stimulation pressure. Observed variation in corneal tissue displacements were not associated with tissue stimulation magnitude, or the amplitude of physiologically induced axial eye motion. Conclusions The microsecond timescale and submicron tissue displacements observed during corneal OCE measurements are separable from normal involuntary physiological movements, such as the oculocardiac pulse and respiratory movements. Translational Relevance This work advances innovations in biomedical imaging and engineering for clinical diagnostic applications for soft-tissue biomechanical testing.
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Affiliation(s)
- Gongpu Lan
- Department of Photoelectric Technology, Foshan University, Foshan, Guangdong, China.,School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Boyu Gu
- Department of Ophthalmology, Doheny Eye Institute, University of California -Los Angeles, Los Angeles, CA, USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Michael D Twa
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA.,College of Optometry, University of Houston, Houston, TX, USA
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Measurement of Retinal Microvascular Blood Velocity Using Erythrocyte Mediated Velocimetry. Sci Rep 2019; 9:20178. [PMID: 31882799 PMCID: PMC6934793 DOI: 10.1038/s41598-019-56239-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/07/2019] [Indexed: 01/08/2023] Open
Abstract
Changes in retinal blood flow may be involved in the pathogenesis of glaucoma and other ocular diseases. Erythrocyte mediated velocimetry (EMV) is a novel technique where indocyanine green (ICG) dye is sequestered in erythrocyte ghosts and autologously re-injected to allow direct visualization of erythrocytes for in vivo measurement of speed. The purpose of this study is to determine the mean erythrocyte speed in the retinal microvasculature, as well as the intravisit and intervisit variability of EMV. Data from 23 EMV sessions from control, glaucoma suspect, and glaucoma patients were included in this study. In arteries with an average diameter of 43.11 µm ± 6.62 µm, the mean speed was 7.17 mm/s ± 2.35 mm/s. In veins with an average diameter of 45.87 µm ± 12.04 µm, the mean speed was 6.05 mm/s ± 1.96 mm/s. Intravisit variability, as measured by the mean coefficient of variation, was 3.57% (range 0.44-9.68%). Intervisit variability was 4.85% (range 0.15-8.43%). EMV may represent reliable method for determination of retinal blood speed, potentially allowing insights into the effects of pharmacologic agents or pathogenesis of ocular diseases.
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33
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Xu X, Yannuzzi NA, Fernández-Avellaneda P, Echegaray JJ, Tran KD, Russell JF, Patel NA, Hussain RM, Sarraf D, Freund KB. Differentiating Veins From Arteries on Optical Coherence Tomography Angiography by Identifying Deep Capillary Plexus Vortices. Am J Ophthalmol 2019; 207:363-372. [PMID: 31226248 DOI: 10.1016/j.ajo.2019.06.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 06/07/2019] [Accepted: 06/08/2019] [Indexed: 01/26/2023]
Abstract
PURPOSE To introduce a simple method for differentiating retinal veins from arteries on optical coherence tomography angiography (OCTA). DESIGN Cross-sectional pilot study. METHODS Four default en face slabs including color depth encoded, grayscale full-thickness retina, superficial plexus, and deep capillary plexus (DCP) from nine 3×3-mm and nine 6×6-mm OCTA scans were exported and aligned. Nine ophthalmologists with minimum OCTA experience from 2 eye institutions were instructed to classify labeled vessels as arteries or veins in 3 stages. Classification was performed based on graders' own assessment at stage 1. Graders were taught that a capillary-free zone was an anatomic feature of arteries at stage 2 and were trained to identify veins originating from vortices within the DCP at stage 3. Grading accuracy was analyzed and correlated with grading time and graders' years in practice. RESULTS Overall grading accuracy in stages 1, 2, and 3 was (50.4% ± 17.0%), (75.4% ± 6.0%), and (94.7% ± 2.6%), respectively. Grading accuracy for 3×3-mm scans in stages 1, 2, and 3 was (49.9% ± 16.3%), (79.2% ± 9.6%), and (96.9% ± 3.1%), respectively. Accuracy for 6×6-mm scans in stages 1, 2, and 3 was (51.4% ± 20.8%), (72.3% ± 7.9%), and (93.2% ± 3.3%), respectively. Grading performance improved significantly at each stage (all P < .001). No significant correlation was found between accuracy and time spent grading or between accuracy and years in practice (r = -0.164 to 0.617, all P ≥ .077). CONCLUSIONS We describe a simple method for accurately distinguishing retinal arteries from veins on OCTA, which incorporates the use of vortices in the DCP to identify venous origin.
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Affiliation(s)
- Xiaoyu Xu
- Vitreous Retina Macula Consultants of New York, New York, New York, USA; LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear, and Throat Hospital, New York, New York, USA; State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Nicolas A Yannuzzi
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Pedro Fernández-Avellaneda
- Vitreous Retina Macula Consultants of New York, New York, New York, USA; LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear, and Throat Hospital, New York, New York, USA; Department of Ophthalmology, Basurto University Hospital, Bilbao, Spain
| | - Jose J Echegaray
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Kimberly D Tran
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jonathan F Russell
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nimesh A Patel
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Rehan M Hussain
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - David Sarraf
- Stein Eye Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - K Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, New York, USA; LuEsther T. Mertz Retinal Research Center, Manhattan Eye, Ear, and Throat Hospital, New York, New York, USA; Department of Ophthalmology, New York University of Medicine; Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, New York, USA.
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Bedggood P, Metha A. Imaging relative stasis of the blood column in human retinal capillaries. BIOMEDICAL OPTICS EXPRESS 2019; 10:6009-6028. [PMID: 31799061 PMCID: PMC6865114 DOI: 10.1364/boe.10.006009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 05/31/2023]
Abstract
Capillary flow largely consists of alternating red cells and plasma whose speed oscillates predictably with the cardiac cycle. Superimposed on this regular background are sporadic events potentially disruptive to capillary exchange: the passage of white cells, aggregates of red cells, epochs of sparse haematocrit, or unusually slow flow. Such events are not readily differentiated with velocimetry or perfusion mapping. Here we propose a method to identify these phenomena in retinal capillaries imaged with high frame-rate adaptive optics, by calculating and representing pictorially the autocorrelation of intensity through time at each pixel during short epochs. The phenomena described above manifest as bright regions which transiently appear and propagate across an otherwise dark image. Drawing data from normal subjects and those with Type I diabetes, we demonstrate proof of concept and high sensitivity and specificity of this metric to variations in capillary contents and rate of flow in health and disease. The proposed metric offers a useful adjunct to velocimetry and perfusion mapping in the study of normal and abnormal capillary blood flow.
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Affiliation(s)
- Phillip Bedggood
- Department of Optometry and Vision Sciences, The University of Melbourne, 3010, Australia
| | - Andrew Metha
- Department of Optometry and Vision Sciences, The University of Melbourne, 3010, Australia
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35
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Wang Y, He Y, Wei L, Yang J, Li X, Zhou H, Shi G, Zhang Y. Bimorph deformable mirror-based adaptive optics scanning laser ophthalmoscope for the clinical design and performance. NEUROPHOTONICS 2019; 6:041111. [PMID: 31720308 PMCID: PMC6830288 DOI: 10.1117/1.nph.6.4.041111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
We developed a clinical ophthalmic prototype by combining bimorph deformable mirror (DM)-based adaptive optics (AO) with a confocal scanning laser ophthalmoscope. A low-cost bimorph DM with a large stroke of 50 μ m and an aperture of 20 mm was utilized to realize a strategy for successive AO control of aberration correction, which permitted open-loop compensation for low-order aberrations and closed-loop correction of high-order aberrations to acceptable root mean square errors of < 0.08 μ m in all subjects. Spherical mirrors were folded in a nonplanar configuration to minimize off-axis aberrations and provide a compact, cost-effective design, which achieved a diffraction-limited performance capable of imaging individual photoreceptor cells and blood vessels not only in healthy subjects but also in patients suffering from retinitis pigmentosa. The adaptive optics scanning laser ophthalmoscope (AOSLO) images of the diseased retina had much higher resolutions than those captured by the commercial AO fundus camera, and loss of the photoreceptor mosaic could be distinguished more accurately due to the improvement in resolution. The compact design and easy handling of the bimorph DM-based AO control may facilitate the translation of AOSLO into clinical settings, and this prototype development will continue with future device refinement and extensive clinical testing.
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Affiliation(s)
- Yuanyuan Wang
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- Wenzhou Medical University, Wenzhou, China
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
| | - Yi He
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
- Jiangsu Key Laboratory of Medical Optics, Suzhou, China
- Chinese Academy of Sciences, Suzhou Institute of Biomedical Engineering and Technology, Suzhou, China
| | - Ling Wei
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
| | - Jinsheng Yang
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
| | - Xiqi Li
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
| | - Hong Zhou
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
| | - Guohua Shi
- Jiangsu Key Laboratory of Medical Optics, Suzhou, China
- Chinese Academy of Sciences, Suzhou Institute of Biomedical Engineering and Technology, Suzhou, China
| | - Yudong Zhang
- Chinese Academy of Sciences, Key Laboratory on Adaptive Optics, Chengdu, China
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36
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Puyo L, Paques M, Fink M, Sahel JA, Atlan M. Waveform analysis of human retinal and choroidal blood flow with laser Doppler holography. BIOMEDICAL OPTICS EXPRESS 2019; 10:4942-4963. [PMID: 31646021 PMCID: PMC6788604 DOI: 10.1364/boe.10.004942] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/14/2019] [Accepted: 06/27/2019] [Indexed: 05/20/2023]
Abstract
Laser Doppler holography was introduced as a full-field imaging technique to measure blood flow in the retina and choroid with an as yet unrivaled temporal resolution. We here investigate separating the different contributions to the power Doppler signal in order to isolate the flow waveforms of vessels in the posterior pole of the human eye. Distinct flow behaviors are found in retinal arteries and veins with seemingly interrelated waveforms. We demonstrate a full field mapping of the local resistivity index, and the possibility to perform unambiguous identification of retinal arteries and veins on the basis of their systolodiastolic variations. Finally we investigate the arterial flow waveforms in the retina and choroid and find synchronous and similar waveforms, although with a lower pulsatility in choroidal arteries. This work demonstrates the potential held by laser Doppler holography to study ocular hemodynamics in healthy and diseased eyes.
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Affiliation(s)
- Léo Puyo
- Institut Langevin, Centre National de la Recherche Scientifique (CNRS), Paris Sciences & Lettres (PSL University), École Supérieure de Physique et de Chimie Industrielles (ESPCI Paris) - 1 rue Jussieu, 75005 Paris, France
- Paris Adaptive Optics, Retinal Imaging, and Surgery, Paris, France
| | - Michel Paques
- Paris Adaptive Optics, Retinal Imaging, and Surgery, Paris, France
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Institut de la Vision-Sorbonne Universités, 17 rue Moreau, 75012 Paris, France
| | - Mathias Fink
- Institut Langevin, Centre National de la Recherche Scientifique (CNRS), Paris Sciences & Lettres (PSL University), École Supérieure de Physique et de Chimie Industrielles (ESPCI Paris) - 1 rue Jussieu, 75005 Paris, France
- Paris Adaptive Optics, Retinal Imaging, and Surgery, Paris, France
| | - José-Alain Sahel
- Paris Adaptive Optics, Retinal Imaging, and Surgery, Paris, France
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Institut de la Vision-Sorbonne Universités, 17 rue Moreau, 75012 Paris, France
| | - Michael Atlan
- Institut Langevin, Centre National de la Recherche Scientifique (CNRS), Paris Sciences & Lettres (PSL University), École Supérieure de Physique et de Chimie Industrielles (ESPCI Paris) - 1 rue Jussieu, 75005 Paris, France
- Paris Adaptive Optics, Retinal Imaging, and Surgery, Paris, France
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37
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Wang D, Haytham A, Mayo L, Tao Y, Saeedi O. Automated retinal microvascular velocimetry based on erythrocyte mediated angiography. BIOMEDICAL OPTICS EXPRESS 2019; 10:3681-3697. [PMID: 31360609 PMCID: PMC6640827 DOI: 10.1364/boe.10.003681] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/13/2019] [Accepted: 06/17/2019] [Indexed: 05/13/2023]
Abstract
Retinal blood flow is an emerging biomarker in ocular and systemic disease. Erythrocyte mediated angiography (EMA) is a novel technique that provides an easily interpretable blood flow velocity quantification by directly tracing individual moving erythrocyte ghosts over time in vivo, imaged using a scanning laser ophthalmoscope (Heidelberg Retina Angiograph platform). This tracking procedure, however, requires time-consuming manual analysis to determine blood flow. To overcome this current bottleneck, we developed an objective and automated velocimetry approach, EMA - Automated Velocimetry (EMA-AV), which is based on a modified sequential Monte Carlo method. The intra-class correlation coefficient (ICC) between trained human graders and EMA-AV is 0.98 for mean vessel velocity estimation and 0.92 for frame by frame erythrocyte velocity estimation. This study proves EMA-AV is a reliable tool for quantification of retinal microvascular velocity and flow and establishes EMA-AV as a reliable and interpretable tool for quantifying retinal microvascular velocity.
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Affiliation(s)
- Dongyi Wang
- Bio-Imaging and Machine Vision Lab, Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742,
USA
| | - Ayman Haytham
- Aureus University School of Medicine, Wayaca 31C, Oranjestad,
Aruba
| | - Lakyn Mayo
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, 419 W Redwood Street, Suite 470, Baltimore, MD 21201,
USA
| | - Yang Tao
- Bio-Imaging and Machine Vision Lab, Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742,
USA
| | - Osamah Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, 419 W Redwood Street, Suite 470, Baltimore, MD 21201,
USA
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38
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Wang M, Chen N. Three-dimensional cellular imaging in thick biological tissue with confocal detection of one-photon fluorescence in the near-infrared II window. JOURNAL OF BIOPHOTONICS 2019; 12:e201800459. [PMID: 30663282 DOI: 10.1002/jbio.201800459] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
Fluorescence imaging in the second near-infrared optical window (NIR-II, 900-1700 nm) has become a technique of choice for noninvasive in vivo imaging in recent years. Greater penetration depths with high spatial resolution and low background can be achieved with this NIR-II window, owing to low autofluorescence within this optical range and reduced scattering of long wavelength photons. Here, we present a novel design of confocal laser scanning microscope tailored for imaging in the NIR-II window. We showcase the outstanding penetration depth of our confocal setup with a series of imaging experiments. HeLa cells labeled with PbS quantum dots with a peak emission wavelength of 1276 nm can be visualized through a 3.5-mm-thick layer of scattering medium, which is a 0.8% Lipofundin solution. A commercially available organic dye IR-1061 (emission peak at 1132 nm), in its native form, is used for the first time, as a NIR-II fluorescence label in cellular imaging. Our confocal setup is capable of capturing optically sectioned images of IR-1061 labeled chondrocytes in fixed animal cartilage at a depth up to 800 μm, with a superb spatial resolution of around 2 μm.
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Affiliation(s)
- Menghan Wang
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Nanguang Chen
- Department of Biomedical Engineering, National University of Singapore, Singapore
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39
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Mapping flow velocity in the human retinal capillary network with pixel intensity cross correlation. PLoS One 2019; 14:e0218918. [PMID: 31237930 PMCID: PMC6592569 DOI: 10.1371/journal.pone.0218918] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 06/13/2019] [Indexed: 01/01/2023] Open
Abstract
We present a new method for determining cellular velocity in the smallest retinal vascular networks as visualized with adaptive optics. The method operates by comparing the intensity profile of each movie pixel with that of every other pixel, after shifting in time by one frame. The time-shifted pixel which most resembles the reference pixel is deemed to be a 'source' or 'destination' of flow information for that pixel. Velocity in the transverse direction is then calculated by dividing the spatial displacement between the two pixels by the inter-frame period. We call this method pixel intensity cross-correlation, or "PIX". Here we compare measurements derived from PIX to two other state-of-the-art algorithms (particle image velocimetry and the spatiotemporal kymograph), as well as to manually tracked cell data. The examples chosen highlight the potential of the new algorithm to substantially improve spatial and temporal resolution, resilience to noise and aliasing, and assessment of network flow properties compared with existing methods.
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40
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Gofas-Salas E, Mecê P, Mugnier L, Bonnefois AM, Petit C, Grieve K, Sahel J, Paques M, Meimon S. Near infrared adaptive optics flood illumination retinal angiography. BIOMEDICAL OPTICS EXPRESS 2019; 10:2730-2743. [PMID: 31259047 PMCID: PMC6583347 DOI: 10.1364/boe.10.002730] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/06/2018] [Accepted: 12/22/2018] [Indexed: 05/06/2023]
Abstract
Image-based angiography is a well-adapted technique to characterize vasculature, and has been used in retinal neurovascular studies. Because the microvasculature is of particular interest, being the site of exchange between blood and tissue, a high spatio-temporal resolution is required, implying the use of adaptive optics ophthalmoscopes with a high frame rate. Creating the opportunity for decoupled stimulation and imaging of the retina makes the use of near infrared (NIR) imaging light desirable, while the need for a large field of view and a lack of distortion implies the use of a flood illumination-based setup. However, flood-illumination NIR video sequences of erythrocytes, or red blood cells (RBC), have a limited contrast compared to scanning systems and visible light. As a result, they cannot be processed via existing image-based angiography methods. We have therefore developed a new computational method relying on a spatio-temporal filtering of the sequence to isolate blood flow from noise in low-contrast sequences. Applying this computational approach enabled us to perform angiography with an adaptive optics flood illumination ophthalmoscope (AO-FIO) using NIR light, both in bright-field and dark-field modalities. Finally, we demonstrate the capabilities of our system to differentiate blood flow velocity on a retinal capillary network in vivo.
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Affiliation(s)
- Elena Gofas-Salas
- DOTA, ONERA, Université Paris Saclay, F-91123 Palaiseau,
France
- Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012 Paris,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
| | - Pedro Mecê
- DOTA, ONERA, Université Paris Saclay, F-91123 Palaiseau,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
- Quantel Medical, Cournon d’Auvergne,
France
| | - Laurent Mugnier
- DOTA, ONERA, Université Paris Saclay, F-91123 Palaiseau,
France
| | | | - Cyril Petit
- DOTA, ONERA, Université Paris Saclay, F-91123 Palaiseau,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
| | - Kate Grieve
- Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012 Paris,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
- CIC 1423, INSERM, Quinze-Vingts Hospital, Paris,
France
| | - José Sahel
- Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012 Paris,
France
- Quantel Medical, Cournon d’Auvergne,
France
- CIC 1423, INSERM, Quinze-Vingts Hospital, Paris,
France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA,
USA
| | - Michel Paques
- Institut de la Vision, 17 rue Moreau, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, 75012 Paris,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
- CIC 1423, INSERM, Quinze-Vingts Hospital, Paris,
France
| | - Serge Meimon
- DOTA, ONERA, Université Paris Saclay, F-91123 Palaiseau,
France
- PARIS Group - Paris Adaptive-Optics for Retinal Imaging and Surgery, Paris,
France
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41
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Joseph A, Guevara-Torres A, Schallek J. Imaging single-cell blood flow in the smallest to largest vessels in the living retina. eLife 2019; 8:45077. [PMID: 31084705 PMCID: PMC6516827 DOI: 10.7554/elife.45077] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/15/2019] [Indexed: 01/15/2023] Open
Abstract
Tissue light scatter limits the visualization of the microvascular network deep inside the living mammal. The transparency of the mammalian eye provides a noninvasive view of the microvessels of the retina, a part of the central nervous system. Despite its clarity, imperfections in the optics of the eye blur microscopic retinal capillaries, and single blood cells flowing within. This limits early evaluation of microvascular diseases that originate in capillaries. To break this barrier, we use 15 kHz adaptive optics imaging to noninvasively measure single-cell blood flow, in one of the most widely used research animals: the C57BL/6J mouse. Measured flow ranged four orders of magnitude (0.0002-1.55 µL min-1) across the full spectrum of retinal vessel diameters (3.2-45.8 µm), without requiring surgery or contrast dye. Here, we describe the ultrafast imaging, analysis pipeline and automated measurement of millions of blood cell speeds.
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Affiliation(s)
- Aby Joseph
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Andres Guevara-Torres
- Institute of Optics, University of Rochester, New York, United States.,Center for Visual Science, University of Rochester, New York, United States
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, New York, United States.,Flaum Eye Institute, University of Rochester, New York, United States.,Department of Neuroscience, University of Rochester, New York, United States
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42
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Burns SA, Elsner AE, Sapoznik KA, Warner RL, Gast TJ. Adaptive optics imaging of the human retina. Prog Retin Eye Res 2019; 68:1-30. [PMID: 30165239 PMCID: PMC6347528 DOI: 10.1016/j.preteyeres.2018.08.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/18/2022]
Abstract
Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.
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Affiliation(s)
- Stephen A Burns
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States.
| | - Ann E Elsner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kaitlyn A Sapoznik
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Raymond L Warner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Thomas J Gast
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
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Jung H, Liu T, Liu J, Huryn LA, Tam J. Combining multimodal adaptive optics imaging and angiography improves visualization of human eyes with cellular-level resolution. Commun Biol 2018; 1:189. [PMID: 30456310 PMCID: PMC6235967 DOI: 10.1038/s42003-018-0190-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/09/2018] [Indexed: 12/12/2022] Open
Abstract
Visualizing the cellular manifestation of disease has recently been aided by an increasing number of adaptive optics (AO)-based imaging modalities developed for the living human eye. However, simultaneous visualization of multiple, interacting cell types within a complete neural-epithelial-vascular complex has proven challenging. By incorporating AO with indocyanine green angiography, we demonstrate the possibility of imaging photoreceptors, retinal pigment epithelial cells, and choriocapillaris in the living human eye. Unexpectedly, we found that there was uptake of indocyanine green dye into the retinal pigment epithelial cells in the earliest phases of imaging, which formed the basis for devising a strategy to visualize the choriocapillaris. Our results expand the range of applications for an existing, FDA-approved, systemically injected fluorescent dye. The combined multimodal approach can be used to evaluate the complete outer retinal complex at the cellular level, a transformative step toward revealing the in vivo cellular status of neurodegenerative conditions and blinding diseases.
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Affiliation(s)
- HaeWon Jung
- National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Tao Liu
- National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jianfei Liu
- National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Laryssa A Huryn
- National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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