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Power D, Elstrott J, Schallek J. Photoreceptor loss does not recruit neutrophils despite strong microglial activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595864. [PMID: 38854151 PMCID: PMC11160676 DOI: 10.1101/2024.05.25.595864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
In response to central nervous system (CNS) injury, tissue resident immune cells such as microglia and circulating systemic neutrophils are often first responders. The degree to which these cells interact in response to CNS damage is poorly understood, and even less so, in the neural retina which poses a challenge for high resolution imaging in vivo. In this study, we deploy fluorescence adaptive optics scanning light ophthalmoscopy (AOSLO) to study fluorescent microglia and neutrophils in mice. We simultaneously track immune cell dynamics using label-free phase-contrast AOSLO at micron-level resolution. Retinal lesions were induced with 488 nm light focused onto photoreceptor (PR) outer segments. These lesions focally ablated PRs, with minimal collateral damage to cells above and below the plane of focus. We used in vivo (AOSLO, SLO and OCT) imaging to reveal the natural history of the microglial and neutrophil response from minutes-to-months after injury. While microglia showed dynamic and progressive immune response with cells migrating into the injury locus within 1-day after injury, neutrophils were not recruited despite close proximity to vessels carrying neutrophils only microns away. Post-mortem confocal microscopy confirmed in vivo findings. This work illustrates that microglial activation does not recruit neutrophils in response to acute, focal loss of photoreceptors, a condition encountered in many retinal diseases.
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Feng G, Joseph A, Dholakia K, Shang F, Pfeifer CW, Power D, Padmanabhan K, Schallek J. High-resolution structural and functional retinal imaging in the awake behaving mouse. Commun Biol 2023; 6:572. [PMID: 37248385 PMCID: PMC10227058 DOI: 10.1038/s42003-023-04896-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 05/02/2023] [Indexed: 05/31/2023] Open
Abstract
The laboratory mouse has provided tremendous insight to the underpinnings of mammalian central nervous system physiology. In recent years, it has become possible to image single neurons, glia and vascular cells in vivo by using head-fixed preparations combined with cranial windows to study local networks of activity in the living brain. Such approaches have also succeeded without the use of general anesthesia providing insights to the natural behaviors of the central nervous system. However, the same has not yet been developed for the eye, which is constantly in motion. Here we characterize a novel head-fixed preparation that enables high-resolution adaptive optics retinal imaging at the single-cell level in awake-behaving mice. We reveal three new functional attributes of the normal eye that are overlooked by anesthesia: 1) High-frequency, low-amplitude eye motion of the mouse that is only present in the awake state 2) Single-cell blood flow in the mouse retina is reduced under anesthesia and 3) Mouse retinae thicken in response to ketamine/xylazine anesthesia. Here we show key benefits of the awake-behaving preparation that enables study of retinal physiology without anesthesia to study the normal retinal physiology in the mouse.
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Affiliation(s)
- Guanping Feng
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14620, USA
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
| | - Aby Joseph
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14620, USA
| | - Kosha Dholakia
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14620, USA
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
| | - Fei Shang
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- Department of Neuroscience, University of Rochester, Rochester, NY, 14642, USA
| | - Charles W Pfeifer
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Derek Power
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
| | - Krishnan Padmanabhan
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- Department of Neuroscience, University of Rochester, Rochester, NY, 14642, USA
- Intellectual and Developmental Disabilities Research Center, University of Rochester, Rochester, NY, 14642, USA
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA.
- Department of Neuroscience, University of Rochester, Rochester, NY, 14642, USA.
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA.
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3
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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: 7] [Impact Index Per Article: 3.5] [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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4
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Lu R, Aguilera N, Liu T, Liu J, Giannini JP, Li J, Bower AJ, Dubra A, Tam J. In-vivo sub-diffraction adaptive optics imaging of photoreceptors in the human eye with annular pupil illumination and sub-Airy detection. OPTICA 2021; 8:333-343. [PMID: 34504903 PMCID: PMC8425240 DOI: 10.1364/optica.414206] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/08/2021] [Indexed: 05/18/2023]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows non-invasive visualization of the living human eye at the microscopic scale; but even with correction of the ocular wavefront aberrations over a large pupil, the smallest cells in the photoreceptor mosaic cannot always be resolved. Here, we synergistically combine annular pupil illumination with sub-Airy disk confocal detection to demonstrate a 33% improvement in transverse resolution (from 2.36 to 1.58 μm) and a 13% axial resolution enhancement (from 37 to 32 μm), an important step towards the study of the complete photoreceptor mosaic in heath and disease. Interestingly, annular pupil illumination also enhanced the visualization of the photoreceptor mosaic in non-confocal detection schemes such as split detection AOSLO, providing a strategy for enhanced multimodal imaging of the cone and rod photoreceptor mosaic.
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Affiliation(s)
- Rongwen Lu
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nancy Aguilera
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Tao Liu
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jianfei Liu
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - John P. Giannini
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Joanne Li
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Andrew J. Bower
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, California 94305, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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5
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Sredar N, Razeen M, Kowalski B, Carroll J, Dubra A. Comparison of confocal and non-confocal split-detection cone photoreceptor imaging. BIOMEDICAL OPTICS EXPRESS 2021; 12:737-755. [PMID: 33680539 PMCID: PMC7901313 DOI: 10.1364/boe.403907] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 05/06/2023]
Abstract
Quadrant reflectance confocal and non-confocal scanning light ophthalmoscope images of the photoreceptor mosaic were recorded in a subject with congenital achromatopsia (ACHM) and a normal control. These images, captured with various circular and annular apertures, were used to calculate split-detection images, revealing two cone photoreceptor contrast mechanisms. The first contrast mechanism, maximal in the non-confocal 5.5-10 Airy disk diameter annular region, is unrelated to the cone reflectivity in confocal or flood illumination imaging. The second mechanism, maximal for confocal split-detection, is related to the cone reflectivity in confocal or flood illumination imaging that originates from the ellipsoid zone and/or inner-outer segment junction. Seeking to maximize image contrast, split-detection images were generated using various quadrant detector combinations, with opposite (diagonal) quadrant detectors producing the highest contrast. Split-detection generated with the addition of adjacent quadrant detector pairs, shows lower contrast, while azimuthal split-detection images, calculated from adjacent quadrant detectors, showed the lowest contrast. Finally, the integration of image pairs with orthogonal split directions was used to produce images in which the photoreceptor contrast does not change with direction.
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Affiliation(s)
- Nripun Sredar
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
| | - Moataz Razeen
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
| | | | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
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Abstract
Adaptive optics (AO) is a technique that corrects for optical aberrations. It was originally proposed to correct for the blurring effect of atmospheric turbulence on images in ground-based telescopes and was instrumental in the work that resulted in the Nobel prize-winning discovery of a supermassive compact object at the centre of our galaxy. When AO is used to correct for the eye's imperfect optics, retinal changes at the cellular level can be detected, allowing us to study the operation of the visual system and to assess ocular health in the microscopic domain. By correcting for sample-induced blur in microscopy, AO has pushed the boundaries of imaging in thick tissue specimens, such as when observing neuronal processes in the brain. In this primer, we focus on the application of AO for high-resolution imaging in astronomy, vision science and microscopy. We begin with an overview of the general principles of AO and its main components, which include methods to measure the aberrations, devices for aberration correction, and how these components are linked in operation. We present results and applications from each field along with reproducibility considerations and limitations. Finally, we discuss future directions.
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7
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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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Joseph A, Chu CJ, Feng G, Dholakia K, Schallek J. Label-free imaging of immune cell dynamics in the living retina using adaptive optics. eLife 2020; 9:e60547. [PMID: 33052099 PMCID: PMC7556865 DOI: 10.7554/elife.60547] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/15/2020] [Indexed: 11/25/2022] Open
Abstract
Our recent work characterized the movement of single blood cells within the retinal vasculature (Joseph et al. 2019) using adaptive optics ophthalmoscopy. Here, we apply this technique to the context of acute inflammation and discover both infiltrating and tissue-resident immune cells to be visible without any labeling in the living mouse retina using near-infrared light alone. Intravital imaging of immune cells can be negatively impacted by surgical manipulation, exogenous dyes, transgenic manipulation and phototoxicity. These confounds are now overcome, using phase contrast and time-lapse videography to reveal the dynamic behavior of myeloid cells as they interact, extravasate and survey the mouse retina. Cellular motility and differential vascular responses were measured noninvasively and in vivo across hours to months at the same retinal location, from initiation to the resolution of inflammation. As comparable systems are already available for clinical research, this approach could be readily translated to human application.
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Affiliation(s)
- Aby Joseph
- The Institute of Optics, University of RochesterRochesterUnited States
| | - Colin J Chu
- Translational Health Sciences, University of BristolBristolUnited Kingdom
| | - Guanping Feng
- Department of Biomedical Engineering, University of RochesterRochesterUnited States
| | - Kosha Dholakia
- Flaum Eye Institute, University of RochesterRochesterUnited States
| | - Jesse Schallek
- Flaum Eye Institute, University of RochesterRochesterUnited States
- Department of Neuroscience and the Del Monte Institute for Neuroscience, University of RochesterRochesterUnited States
- Center for Visual Science, University of RochesterRochesterUnited States
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9
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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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10
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Laforest T, Künzi M, Kowalczuk L, Carpentras D, Behar-Cohen F, Moser C. Transscleral Optical Phase Imaging of the Human Retina. NATURE PHOTONICS 2020; 14:439-445. [PMID: 32607125 PMCID: PMC7326609 DOI: 10.1038/s41566-020-0608-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In-vivo observation of the human retina at the cellular level is crucial to detect the first signs of retinal diseases and properly treat them. Despite the phenomenal advances in adaptive optics (AO) systems, clinical imaging of many retinal cells is still elusive due to the low signal-to-noise ratio induced by transpupillary illumination. We present a transscleral optical phase imaging (TOPI) method, which relies on high-angle oblique illumination of the retina, combined with AO, to enhance cell contrast. Examination of eleven healthy volunteer eyes, without pupil dilation, shows the ability of this method to produce in-vivo images of retinal cells, from the retinal pigment epithelium to the nerve fibre layer. This method also allows the generation of high-resolution label-free ex-vivo phase images of flat-mounted retinas. The 4.4°x 4.4° field-of-view in-vivo images are recorded in less than 10 seconds, opening new avenues in the exploration of healthy and diseased retinas.
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Affiliation(s)
- T. Laforest
- Laboratory of Applied Photonic Devices (LAPD), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- EarlySight SA, EPFL Innovation Park, Lausanne, Switzerland
| | - M. Künzi
- Laboratory of Applied Photonic Devices (LAPD), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- EarlySight SA, EPFL Innovation Park, Lausanne, Switzerland
| | - L. Kowalczuk
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - D. Carpentras
- Laboratory of Applied Photonic Devices (LAPD), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - F. Behar-Cohen
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Centre de Recherche des Cordeliers, Inserm, USPC, Université de Paris, Sorbonne Université, From physiopathology of ocular diseases to clinical developments, F-75006 Paris, France
- Ophtalmopole, Hôpital Cochin, Assistance Publique Hôpitaux de Paris, Université de Paris, Paris, France
| | - C. Moser
- Laboratory of Applied Photonic Devices (LAPD), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Materials and Correspondence: Correspondence and requests for materials should be addressed to
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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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12
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Guevara-Torres A, Williams DR, Schallek J. Origin of cell contrast in offset aperture adaptive optics ophthalmoscopy. OPTICS LETTERS 2020; 45:840-843. [PMID: 32058484 PMCID: PMC7337096 DOI: 10.1364/ol.382589] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/18/2019] [Indexed: 05/18/2023]
Abstract
Offset aperture and split detector imaging are variants of adaptive optics scanning ophthalmoscopy recently introduced to improve the image contrast of retinal cells. Unlike conventional confocal scanning ophthalmoscopy, these approaches collect light laterally decentered from the optical axis. A complete explanation of how these methods enhance contrast has not been described. Here, we provide an optical model with supporting in vivo data that show contrast is generated from spatial variations in the refractive index as it is in phase contrast microscopy. A prediction of this model is supported by experimental data that show contrast is optimized when the detector is placed conjugate with a deeper backscattering screen such as the retinal pigment epithelium and choroid, rather than with the layer being imaged as in conventional confocal imaging. This detection strategy provides a substantial improvement in the contrast these new methods can produce.
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Affiliation(s)
- A. Guevara-Torres
- Center for Visual Science, University of Rochester, Rochester, NY, 14642, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14620, USA
- Corresponding author:
| | - D. R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, 14642, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14620, USA
| | - J.B. Schallek
- Center for Visual Science, University of Rochester, Rochester, NY, 14642, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
- Department of Neuroscience, University of Rochester, Rochester, NY, 14620, USA
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13
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Zhang P, Miller EB, Manna SK, Meleppat RK, Pugh EN, Zawadzki RJ. Temporal speckle-averaging of optical coherence tomography volumes for in-vivo cellular resolution neuronal and vascular retinal imaging. NEUROPHOTONICS 2019; 6:041105. [PMID: 31528657 PMCID: PMC6732665 DOI: 10.1117/1.nph.6.4.041105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/31/2019] [Indexed: 05/08/2023]
Abstract
It has been recently demonstrated that structures corresponding to the cell bodies of highly transparent cells in the retinal ganglion cell layer could be visualized noninvasively in the living human eye by optical coherence tomography (OCT) via temporal averaging. Inspired by this development, we explored the application of volumetric temporal averaging in mice, which are important models for studying human retinal diseases and therapeutic interventions. A general framework of temporal speckle-averaging (TSA) of OCT and optical coherence tomography angiography (OCTA) is presented and applied to mouse retinal volumetric data. Based on the image analysis, the eyes of mice under anesthesia exhibit only minor motions, corresponding to lateral displacements of a few micrometers and rotations of a fraction of 1 deg. Moreover, due to reduced eye movements under anesthesia, there is a negligible amount of motion artifacts within the volumes that need to be corrected to achieve volume coregistration. In addition, the relatively good optical quality of the mouse ocular media allows for cellular-resolution imaging without adaptive optics (AO), greatly simplifying the experimental system, making the proposed framework feasible for large studies. The TSA OCT and TSA OCTA results provide rich information about new structures previously not visualized in living mice with non-AO-OCT. The mechanism of TSA relies on improving signal-to-noise ratio as well as efficient suppression of speckle contrast due to temporal decorrelation of the speckle patterns, enabling full utilization of the high volumetric resolution offered by OCT and OCTA.
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Affiliation(s)
- Pengfei Zhang
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Eric B. Miller
- University of California Davis, Center for Neuroscience, Davis, California, United States
| | - Suman K. Manna
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Ratheesh K. Meleppat
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Edward N. Pugh
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
- University of California Davis, Department of Ophthalmology and Vision Science, Vision Science and Advanced Retinal Imaging Laboratory, Sacramento, California, United States
| | - Robert J. Zawadzki
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
- University of California Davis, Department of Ophthalmology and Vision Science, Vision Science and Advanced Retinal Imaging Laboratory, Sacramento, California, United States
- University of California Davis, UC Davis Eye Center, Department of Ophthalmology and Vision Science, Sacramento, California, United States
- Address all correspondence to Robert J. Zawadzki, E-mail:
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Wahl DJ, Ju MJ, Jian Y, Sarunic MV. Non-invasive cellular-resolution retinal imaging with two-photon excited fluorescence. BIOMEDICAL OPTICS EXPRESS 2019; 10:4859-4873. [PMID: 31565530 PMCID: PMC6757458 DOI: 10.1364/boe.10.004859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/13/2019] [Accepted: 08/13/2019] [Indexed: 05/02/2023]
Abstract
Two-photon excited fluorescence (TPEF) imaging of the retina is a developing technique that provides non-invasive compound-specific measurements from the retina. In this report, we demonstrate high-resolution TPEF imaging of the mouse retina using sensorless adaptive optics (SAO) and optical coherence tomography (OCT). A single near-infrared light source was used for simultaneous multi-modal imaging with OCT and TPEF. The image-based SAO could be performed using the en face OCT or the TPEF for aberration correction. Our results demonstrate OCT and TPEF for angiography. Also, we demonstrate non-invasive cellular-resolution imaging of fluorescently labelled cells and the Retinal Pigment Epithelium (RPE) mosaic.
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Affiliation(s)
- Daniel J. Wahl
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - Myeong Jin Ju
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - Yifan Jian
- Engineering Science, Simon Fraser University, Burnaby, BC, Canada
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
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15
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Alarcon-Martinez L, Yilmaz-Ozcan S, Yemisci M, Schallek J, Kılıç K, Villafranca-Baughman D, Can A, Di Polo A, Dalkara T. Retinal ischemia induces α-SMA-mediated capillary pericyte contraction coincident with perivascular glycogen depletion. Acta Neuropathol Commun 2019; 7:134. [PMID: 31429795 PMCID: PMC6701129 DOI: 10.1186/s40478-019-0761-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/26/2019] [Indexed: 12/21/2022] Open
Abstract
Increasing evidence indicates that pericytes are vulnerable cells, playing pathophysiological roles in various neurodegenerative processes. Microvascular pericytes contract during cerebral and coronary ischemia and do not relax after re-opening of the occluded artery, causing incomplete reperfusion. However, the cellular mechanisms underlying ischemia-induced pericyte contraction, its delayed emergence, and whether it is pharmacologically reversible are unclear. Here, we investigate i) whether ischemia-induced pericyte contractions are mediated by alpha-smooth muscle actin (α-SMA), ii) the sources of calcium rise in ischemic pericytes, and iii) if peri-microvascular glycogen can support pericyte metabolism during ischemia. Thus, we examined pericyte contractility in response to retinal ischemia both in vivo, using adaptive optics scanning light ophthalmoscopy and, ex vivo, using an unbiased stereological approach. We found that microvascular constrictions were associated with increased calcium in pericytes as detected by a genetically encoded calcium indicator (NG2-GCaMP6) or a fluoroprobe (Fluo-4). Knocking down α-SMA expression with RNA interference or fixing F-actin with phalloidin or calcium antagonist amlodipine prevented constrictions, suggesting that constrictions resulted from calcium- and α-SMA-mediated pericyte contractions. Carbenoxolone or a Cx43-selective peptide blocker also reduced calcium rise, consistent with involvement of gap junction-mediated mechanisms in addition to voltage-gated calcium channels. Pericyte calcium increase and capillary constrictions became significant after 1 h of ischemia and were coincident with depletion of peri-microvascular glycogen, suggesting that glucose derived from glycogen granules could support pericyte metabolism and delay ischemia-induced microvascular dysfunction. Indeed, capillary constrictions emerged earlier when glycogen breakdown was pharmacologically inhibited. Constrictions persisted despite recanalization but were reversible with pericyte-relaxant adenosine administered during recanalization. Our study demonstrates that retinal ischemia, a common cause of blindness, induces α-SMA- and calcium-mediated persistent pericyte contraction, which can be delayed by glucose driven from peri-microvascular glycogen. These findings clarify the contractile nature of capillary pericytes and identify a novel metabolic collaboration between peri-microvascular end-feet and pericytes.
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Affiliation(s)
- Luis Alarcon-Martinez
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Sinem Yilmaz-Ozcan
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
| | - Muge Yemisci
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey.
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Jesse Schallek
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, USA
| | - Kıvılcım Kılıç
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
| | - Deborah Villafranca-Baughman
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Alp Can
- Department of Histology and Embryology, School of Medicine, Ankara University, Ankara, Turkey
| | - Adriana Di Polo
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey.
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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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: 48] [Impact Index Per Article: 9.6] [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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Liu J, Jung H, Dubra A, Tam J. Cone Photoreceptor Cell Segmentation and Diameter Measurement on Adaptive Optics Images Using Circularly Constrained Active Contour Model. Invest Ophthalmol Vis Sci 2019; 59:4639-4652. [PMID: 30372733 PMCID: PMC6154284 DOI: 10.1167/iovs.18-24734] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purpose Cone photoreceptor cells can be noninvasively imaged in the living human eye by using nonconfocal adaptive optics scanning ophthalmoscopy split detection. Existing metrics, such as cone density and spacing, are based on simplifying cone photoreceptors to single points. The purposes of this study were to introduce a computer-aided approach for segmentation of cone photoreceptors, to apply this technique to create a normal database of cone diameters, and to demonstrate its use in the context of existing metrics. Methods Cone photoreceptor segmentation is achieved through a circularly constrained active contour model (CCACM). Circular templates and image gradients attract active contours toward cone photoreceptor boundaries. Automated segmentation from in vivo human subject data was compared to ground truth established by manual segmentation. Cone diameters computed from curated data (automated segmentation followed by manual removal of errors) were compared with histology and published data. Results Overall, there was good agreement between automated and manual segmentations and between diameter measurements (n = 5191 cones) and published histologic data across retinal eccentricities ranging from 1.35 to 6.35 mm (temporal). Interestingly, cone diameter was correlated to both cone density and cone spacing (negatively and positively, respectively; P < 0.01 for both). Application of the proposed automated segmentation to images from a patient with late-onset retinal degeneration revealed the presence of enlarged cones above individual reticular pseudodrusen (average 23.0% increase, P < 0.05). Conclusions CCACM can accurately segment cone photoreceptors on split detection images across a range of eccentricities. Metrics derived from this automated segmentation of adaptive optics retinal images can provide new insights into retinal diseases.
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Affiliation(s)
- Jianfei Liu
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - HaeWon Jung
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, California, United States
| | - Johnny Tam
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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18
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Walters S, Schwarz C, Sharma R, Rossi EA, Fischer WS, DiLoreto DA, Strazzeri J, Nelidova D, Roska B, Hunter JJ, Williams DR, Merigan WH. Cellular-scale evaluation of induced photoreceptor degeneration in the living primate eye. BIOMEDICAL OPTICS EXPRESS 2019; 10:66-82. [PMID: 30775083 PMCID: PMC6363191 DOI: 10.1364/boe.10.000066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 05/06/2023]
Abstract
Progress is needed in developing animal models of photoreceptor degeneration and evaluating such models with longitudinal, noninvasive techniques. We employ confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT) and high-resolution retinal imaging to noninvasively observe the retina of non-human primates with induced photoreceptor degeneration. Photoreceptors were imaged at the single-cell scale in three modalities of adaptive optics scanning light ophthalmoscopy: traditional confocal reflectance, indicative of waveguiding; a non-confocal offset aperture technique visualizing scattered light; and two-photon excited fluorescence, the time-varying signal of which, at 730 nm excitation, is representative of visual cycle function. Assessment of photoreceptor structure and function using these imaging modalities revealed a reduction in retinoid production in cone photoreceptor outer segments while inner segments appeared to remain present. Histology of one retina confirmed loss of outer segments and the presence of intact inner segments. This unique combination of imaging modalities can provide essential, clinically-relevant information on both the structural integrity and function of photoreceptors to not only validate models of photoreceptor degeneration but potentially evaluate the efficacy of future cell and gene-based therapies for vision restoration.
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Affiliation(s)
- Sarah Walters
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with the Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with Facebook Reality Labs, Redmond, WA, USA
| | - Ethan A. Rossi
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with the Departments of Ophthalmology & Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Jennifer Strazzeri
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Dasha Nelidova
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jennifer J. Hunter
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - William H. Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
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Mozaffari S, Jaedicke V, LaRocca F, Tiruveedhula P, Roorda A. Versatile multi-detector scheme for adaptive optics scanning laser ophthalmoscopy. BIOMEDICAL OPTICS EXPRESS 2018; 9:5477-5488. [PMID: 30460141 PMCID: PMC6238903 DOI: 10.1364/boe.9.005477] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/25/2018] [Accepted: 09/28/2018] [Indexed: 05/18/2023]
Abstract
Adaptive optics scanning laser ophthalmoscopy (AOSLO) is a powerful tool for imaging the retina at high spatial and temporal resolution. In this paper, we present a multi-detector scheme for AOSLO which has two main configurations: pixel reassignment and offset aperture imaging. In this detection scheme, the single element detector of the standard AOSLO is replaced by a fiber bundle which couples the detected light into multiple detectors. The pixel reassignment configuration enables high resolution imaging with an increased light collection. The increase in signal-to-noise ratio (SNR) from this configuration can improve the accuracy of motion registration techniques. The offset aperture imaging configuration enhances the detection of multiply scattered light, which improves the contrast of retinal vasculature and inner retinal layers similar to methods such as nonconfocal split-detector imaging and multi-offset aperture imaging.
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Affiliation(s)
- Sanam Mozaffari
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA,
USA
- Contributed equally to this work
| | - Volker Jaedicke
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA,
USA
- Contributed equally to this work
| | - Francesco LaRocca
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA,
USA
| | - Pavan Tiruveedhula
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA,
USA
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA,
USA
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20
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Zhang P, Mocci J, Wahl DJ, Meleppat RK, Manna SK, Quintavalla M, Muradore R, Sarunic MV, Bonora S, Pugh EN, Zawadzki RJ. Effect of a contact lens on mouse retinal in vivo imaging: Effective focal length changes and monochromatic aberrations. Exp Eye Res 2018; 172:86-93. [PMID: 29604280 PMCID: PMC6417837 DOI: 10.1016/j.exer.2018.03.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/26/2018] [Accepted: 03/27/2018] [Indexed: 01/09/2023]
Abstract
For in vivo mouse retinal imaging, especially with Adaptive Optics instruments, application of a contact lens is desirable, as it allows maintenance of cornea hydration and helps to prevent cataract formation during lengthy imaging sessions. However, since the refractive elements of the eye (cornea and lens) serve as the objective for most in vivo retinal imaging systems, the use of a contact lens, even with 0 Dpt. refractive power, can alter the system’s optical properties. In this investigation we examined the effective focal length change and the aberrations that arise from use of a contact lens. First, focal length changes were simulated with a Zemax mouse eye model. Then ocular aberrations with and without a 0 Dpt. contact lens were measured with a Shack-Hartmann wavefront sensor (SHWS) in a customized AO-SLO system. Total RMS wavefront errors were measured for two groups of mice (14-month, and 2.5-month-old), decomposed into 66 Zernike aberration terms, and compared. These data revealed that vertical coma and spherical aberrations were increased with use of a contact lens in our system. Based on the ocular wavefront data we evaluated the effect of the contact lens on the imaging system performance as a function of the pupil size. Both RMS error and Strehl ratios were quantified for the two groups of mice, with and without contact lenses, and for different input beam sizes. These results provide information for determining optimum pupil size for retinal imaging without adaptive optics, and raise critical issues for design of mouse optical imaging systems that incorporate contact lenses.
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Affiliation(s)
- Pengfei Zhang
- UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, United States
| | - Jacopo Mocci
- CNR-Institute for Photonics and Nanotechnology, Via Trasea 7, 35131, Padova, Italy
| | - Daniel J Wahl
- Engineering Science, Simon Fraser University, Burnaby BC, V5A 1S6, Canada
| | - Ratheesh Kumar Meleppat
- UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, United States
| | - Suman K Manna
- UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, United States
| | - Martino Quintavalla
- CNR-Institute for Photonics and Nanotechnology, Via Trasea 7, 35131, Padova, Italy
| | | | - Marinko V Sarunic
- Engineering Science, Simon Fraser University, Burnaby BC, V5A 1S6, Canada
| | - Stefano Bonora
- CNR-Institute for Photonics and Nanotechnology, Via Trasea 7, 35131, Padova, Italy
| | - Edward N Pugh
- UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, United States; UC Davis Eye Center, Dept. of Ophthalmology & Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817, United States
| | - Robert J Zawadzki
- UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616, United States; UC Davis Eye Center, Dept. of Ophthalmology & Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817, United States.
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Carpentras D, Laforest T, Künzi M, Moser C. Effect of backscattering in phase contrast imaging of the retina. OPTICS EXPRESS 2018; 26:6785-6795. [PMID: 29609366 DOI: 10.1364/oe.26.006785] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 02/18/2018] [Indexed: 05/24/2023]
Abstract
The observation of retinal cellular structures is fundamental to the understanding of eye pathologies. However, except for rods and cones, most of the retinal microstructures are weakly reflective and thus difficult to image with state of the art reflective optical imaging techniques such as optical coherence tomography. Recently, we demonstrated the possibility of obtaining the phase contrast of retinal cells in the eye using oblique illumination of the retina. Indeed, by illuminating the eye with incoherent oblique illumination, we obtain a secondary oblique illumination from the backscattered light which can then be used to obtain phase contrast in an effective transmission-like configuration. In this technique, a weak phase signal is modulated over an intense background. Maximizing this phase contrast is thus crucial for the image quality. Here, we investigate the parameters that affect phase contrast by modelling image formation with the backscattered light. We find that the key parameter for maximizing contrast is the intensity profile of the backscattered light. Specifically, the gradient of the profile is found to be proportional to the phase contrast. We validate the model by comparing simulations with experimental results on ex-vivo retina samples.
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22
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Liu J, Jung H, Dubra A, Tam J. Automated Photoreceptor Cell Identification on Nonconfocal Adaptive Optics Images Using Multiscale Circular Voting. Invest Ophthalmol Vis Sci 2017; 58:4477-4489. [PMID: 28873173 PMCID: PMC5586244 DOI: 10.1167/iovs.16-21003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose Adaptive optics scanning light ophthalmoscopy (AOSLO) has enabled quantification of the photoreceptor mosaic in the living human eye using metrics such as cell density and average spacing. These rely on the identification of individual cells. Here, we demonstrate a novel approach for computer-aided identification of cone photoreceptors on nonconfocal split detection AOSLO images. Methods Algorithms for identification of cone photoreceptors were developed, based on multiscale circular voting (MSCV) in combination with a priori knowledge that split detection images resemble Nomarski differential interference contrast images, in which dark and bright regions are present on the two sides of each cell. The proposed algorithm locates dark and bright region pairs, iteratively refining the identification across multiple scales. Identification accuracy was assessed in data from 10 subjects by comparing automated identifications with manual labeling, followed by computation of density and spacing metrics for comparison to histology and published data. Results There was good agreement between manual and automated cone identifications with overall recall, precision, and F1 score of 92.9%, 90.8%, and 91.8%, respectively. On average, computed density and spacing values using automated identification were within 10.7% and 11.2% of the expected histology values across eccentricities ranging from 0.5 to 6.2 mm. There was no statistically significant difference between MSCV-based and histology-based density measurements (P = 0.96, Kolmogorov-Smirnov 2-sample test). Conclusions MSCV can accurately detect cone photoreceptors on split detection images across a range of eccentricities, enabling quick, objective estimation of photoreceptor mosaic metrics, which will be important for future clinical trials utilizing adaptive optics.
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Affiliation(s)
- Jianfei Liu
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - HaeWon Jung
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, California, United States
| | - Johnny Tam
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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23
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Litts KM, Cooper RF, Duncan JL, Carroll J. Photoreceptor-Based Biomarkers in AOSLO Retinal Imaging. Invest Ophthalmol Vis Sci 2017; 58:BIO255-BIO267. [PMID: 28873135 PMCID: PMC5584616 DOI: 10.1167/iovs.17-21868] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/28/2017] [Indexed: 01/08/2023] Open
Abstract
Improved understanding of the mechanisms underlying inherited retinal degenerations has created the possibility of developing much needed treatments for these relentless, blinding diseases. However, standard clinical indicators of retinal health (such as visual acuity and visual field sensitivity) are insensitive measures of photoreceptor survival. In many retinal degenerations, significant photoreceptor loss must occur before measurable differences in visual function are observed. Thus, there is a recognized need for more sensitive outcome measures to assess therapeutic efficacy as numerous clinical trials are getting underway. Adaptive optics (AO) retinal imaging techniques correct for the monochromatic aberrations of the eye and can be used to provide nearly diffraction-limited images of the retina. Many groups routinely are using AO imaging tools to obtain in vivo images of the rod and cone photoreceptor mosaic, and it now is possible to monitor photoreceptor structure over time with single cell resolution. Highlighting recent work using AO scanning light ophthalmoscopy (AOSLO) across a range of patient populations, we review the development of photoreceptor-based metrics (e.g., density/geometry, reflectivity, and size) as candidate biomarkers. Going forward, there is a need for further development of automated tools and normative databases, with the latter facilitating the comparison of data sets across research groups and devices. Ongoing and future clinical trials for inherited retinal diseases will benefit from the improved resolution and sensitivity that multimodal AO retinal imaging affords to evaluate safety and efficacy of emerging therapies.
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Affiliation(s)
- Katie M. Litts
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Robert F. Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Jacque L. Duncan
- Department of Ophthalmology, University of California, San Francisco, California, United States
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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24
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Salmon AE, Cooper RF, Langlo CS, Baghaie A, Dubra A, Carroll J. An Automated Reference Frame Selection (ARFS) Algorithm for Cone Imaging with Adaptive Optics Scanning Light Ophthalmoscopy. Transl Vis Sci Technol 2017; 6:9. [PMID: 28392976 PMCID: PMC5381332 DOI: 10.1167/tvst.6.2.9] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/28/2017] [Indexed: 01/12/2023] Open
Abstract
PURPOSE To develop an automated reference frame selection (ARFS) algorithm to replace the subjective approach of manually selecting reference frames for processing adaptive optics scanning light ophthalmoscope (AOSLO) videos of cone photoreceptors. METHODS Relative distortion was measured within individual frames before conducting image-based motion tracking and sorting of frames into distinct spatial clusters. AOSLO images from nine healthy subjects were processed using ARFS and human-derived reference frames, then aligned to undistorted AO-flood images by nonlinear registration and the registration transformations were compared. The frequency at which humans selected reference frames that were rejected by ARFS was calculated in 35 datasets from healthy subjects, and subjects with achromatopsia, albinism, or retinitis pigmentosa. The level of distortion in this set of human-derived reference frames was assessed. RESULTS The average transformation vector magnitude required for registration of AOSLO images to AO-flood images was significantly reduced from 3.33 ± 1.61 pixels when using manual reference frame selection to 2.75 ± 1.60 pixels (mean ± SD) when using ARFS (P = 0.0016). Between 5.16% and 39.22% of human-derived frames were rejected by ARFS. Only 2.71% to 7.73% of human-derived frames were ranked in the top 5% of least distorted frames. CONCLUSION ARFS outperforms expert observers in selecting minimally distorted reference frames in AOSLO image sequences. The low success rate in human frame choice illustrates the difficulty in subjectively assessing image distortion. TRANSLATIONAL RELEVANCE Manual reference frame selection represented a significant barrier to a fully automated image-processing pipeline (including montaging, cone identification, and metric extraction). The approach presented here will aid in the clinical translation of AOSLO imaging.
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Affiliation(s)
- Alexander E Salmon
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert F Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher S Langlo
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ahmadreza Baghaie
- Department of Electrical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Alfredo Dubra
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA ; Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA ; Current affiliation: Department of Ophthalmology, Stanford University, 2452 Watson Court, Palo Alto, CA, USA
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA ; Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
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25
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Lu J, Gu B, Wang X, Zhang Y. High-speed adaptive optics line scan confocal retinal imaging for human eye. PLoS One 2017; 12:e0169358. [PMID: 28257458 PMCID: PMC5336222 DOI: 10.1371/journal.pone.0169358] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 12/15/2016] [Indexed: 01/03/2023] Open
Abstract
Purpose Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. Methods A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye’s optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. Results The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. Conclusions We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss.
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Affiliation(s)
- Jing Lu
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Boyu Gu
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Xiaolin Wang
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Yuhua Zhang
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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26
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Marcos S, Werner JS, Burns SA, Merigan WH, Artal P, Atchison DA, Hampson KM, Legras R, Lundstrom L, Yoon G, Carroll J, Choi SS, Doble N, Dubis AM, Dubra A, Elsner A, Jonnal R, Miller DT, Paques M, Smithson HE, Young LK, Zhang Y, Campbell M, Hunter J, Metha A, Palczewska G, Schallek J, Sincich LC. Vision science and adaptive optics, the state of the field. Vision Res 2017; 132:3-33. [PMID: 28212982 PMCID: PMC5437977 DOI: 10.1016/j.visres.2017.01.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 12/27/2022]
Abstract
Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Yuhua Zhang
- University of Alabama at Birmingham, Birmingham, USA
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27
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Abstract
Ground squirrels are an increasingly important model for studying visual processing, retinal circuitry, and cone photoreceptor function. Here, we demonstrate that the photoreceptor mosaic can be longitudinally imaged noninvasively in the 13-lined ground squirrel (Ictidomys tridecemlineatus) using confocal and nonconfocal split-detection adaptive optics scanning ophthalmoscopy using 790 nm light. Photoreceptor density, spacing, and Voronoi analysis are consistent with that of the human cone mosaic. The high imaging success rate and consistent image quality in this study reinforce the ground squirrel as a practical model to aid drug discovery and testing through longitudinal imaging on the cellular scale.
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28
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Guevara-Torres A, Joseph A, Schallek JB. Label free measurement of retinal blood cell flux, velocity, hematocrit and capillary width in the living mouse eye. BIOMEDICAL OPTICS EXPRESS 2016; 7:4228-4249. [PMID: 27867728 PMCID: PMC5102544 DOI: 10.1364/boe.7.004228] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 05/02/2023]
Abstract
Measuring blood cell dynamics within the capillaries of the living eye provides crucial information regarding the health of the microvascular network. To date, the study of single blood cell movement in this network has been obscured by optical aberrations, hindered by weak optical contrast, and often required injection of exogenous fluorescent dyes to perform measurements. Here we present a new strategy to non-invasively image single blood cells in the living mouse eye without contrast agents. Eye aberrations were corrected with an adaptive optics camera coupled with a fast, 15 kHz scanned beam orthogonal to a capillary of interest. Blood cells were imaged as they flowed past a near infrared imaging beam to which the eye is relatively insensitive. Optical contrast of cells was optimized using differential scatter of blood cells in the split-detector imaging configuration. Combined, these strategies provide label-free, non-invasive imaging of blood cells in the retina as they travel in single file in capillaries, enabling determination of cell flux, morphology, class, velocity, and rheology at the single cell level.
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Affiliation(s)
- A. Guevara-Torres
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY 14620, USA
| | - A. Joseph
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY 14620, USA
| | - J. B. Schallek
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA
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29
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Chui TYP, Mo S, Krawitz B, Menon NR, Choudhury N, Gan A, Razeen M, Shah N, Pinhas A, Rosen RB. Human retinal microvascular imaging using adaptive optics scanning light ophthalmoscopy. Int J Retina Vitreous 2016; 2:11. [PMID: 27847629 PMCID: PMC5088465 DOI: 10.1186/s40942-016-0037-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/21/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Retinal microvascular imaging is an especially promising application of high resolution imaging since there are increasing options for therapeutic intervention and need for better structural and functional biomarkers to characterize ocular and systemic vascular diseases. MAIN BODY Adaptive optics scanning light ophthalmoscopy (AOSLO) is an emerging technology for improving in vivo imaging of the human retinal microvasculature, allowing unprecedented visualization of retinal microvascular structure, measurements of blood flow velocity, and microvascular network mapping. This high resolution imaging technique shows significant potential for studying physiological and pathological conditions of the retinal microvasculature noninvasively. CONCLUSION This review will briefly summarize the abilities of in vivo human retinal microvasculature imaging in healthy controls, as well as patients with diabetic retinopathy, retinal vein occlusion, and sickle cell retinopathy using AOSLO and discuss its potential contribution to scientific research and clinical applications.
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Affiliation(s)
- Toco Y P Chui
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Shelley Mo
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Brian Krawitz
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Nikhil R Menon
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Nadim Choudhury
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Alexander Gan
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA
| | - Moataz Razeen
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Alexandria Faculty of Medicine, University of Alexandria, Alexandria, Egypt
| | - Nishit Shah
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA
| | - Alexander Pinhas
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Richard B Rosen
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai, New York, NY USA.,Icahn School of Medicine at Mount Sinai, New York, NY USA
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30
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Merino D, Loza-Alvarez P. Adaptive optics scanning laser ophthalmoscope imaging: technology update. Clin Ophthalmol 2016; 10:743-55. [PMID: 27175057 PMCID: PMC4854423 DOI: 10.2147/opth.s64458] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it.
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Affiliation(s)
- David Merino
- The Institute of Photonic Sciences (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Pablo Loza-Alvarez
- The Institute of Photonic Sciences (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
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