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Bautista-Elivar N, Avilés-Trigueros M, Bueno JM. Quantification of Photoreceptors' Changes in a Diabetic Retinopathy Model with Two-Photon Imaging Microscopy. Int J Mol Sci 2024; 25:8756. [PMID: 39201444 PMCID: PMC11354294 DOI: 10.3390/ijms25168756] [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: 06/28/2024] [Revised: 08/01/2024] [Accepted: 08/05/2024] [Indexed: 09/02/2024] Open
Abstract
Emerging evidence suggests that retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR), preceding the development of microvascular abnormalities. Here, we assessed the impact of neuroinflammation on the retina of diabetic-induced rats. For this aim we have used a two-photon microscope to image the photoreceptors (PRs) at different eccentricities in unstained retinas obtained from both control (N = 4) and pathological rats (N = 4). This technique provides high-resolution images where individual PRs can be identified. Within each image, every PR was located, and its transversal area was measured and used as an objective parameter of neuroinflammation. In control samples, the size of the PRs hardly changed with retinal eccentricity. On the opposite end, diabetic retinas presented larger PR transversal sections. The ratio of PRs suffering from neuroinflammation was not uniform across the retina. Moreover, the maximum anatomical resolving power (in cycles/deg) was also calculated. This presents a double-slope pattern (from the central retina towards the periphery) in both types of specimens, although the values for diabetic retinas were significantly lower across all retinal locations. The results show that chronic retinal inflammation due to diabetes leads to an increase in PR transversal size. These changes are not uniform and depend on the retinal location. Two-photon microscopy is a useful tool to accurately characterize and quantify PR inflammatory processes and retinal alterations.
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Affiliation(s)
- Nazario Bautista-Elivar
- Departamento de Ingeniería Eléctrica y Electrónica, Tecnológico Nacional de México/Instituto Tecnológico de Pachuca, Pachuca 42082, Hidalgo, Mexico
| | - Marcelino Avilés-Trigueros
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia e Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, “Campus Mare Nostrum” de Excelencia International, 30100 Murcia, Spain
| | - Juan M. Bueno
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, 30100 Murcia, Spain
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2
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Yu CT, Kandoi S, Periasamy R, Reddy LVK, Follett HM, Summerfelt P, Martinez C, Guillaume C, Bowie O, Connor TB, Lipinski DM, Allen KP, Merriman DK, Carroll J, Lamba DA. Human iPSC-derived photoreceptor transplantation in the cone dominant 13-lined ground squirrel. Stem Cell Reports 2024; 19:331-342. [PMID: 38335965 PMCID: PMC10937153 DOI: 10.1016/j.stemcr.2024.01.005] [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: 09/22/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 02/12/2024] Open
Abstract
Several retinal degenerations affect the human central retina, which is primarily comprised of cones and is essential for high acuity and color vision. Transplanting cone photoreceptors is a promising strategy to replace degenerated cones in this region. Although this approach has been investigated in a handful of animal models, commonly used rodent models lack a cone-rich region and larger models can be expensive and inaccessible, impeding the translation of therapies. Here, we transplanted dissociated GFP-expressing photoreceptors from retinal organoids differentiated from human induced pluripotent stem cells into the subretinal space of damaged and undamaged cone-dominant 13-lined ground squirrel eyes. Transplanted cell survival was documented via noninvasive high-resolution imaging and immunohistochemistry to confirm the presence of human donor photoreceptors for up to 4 months posttransplantation. These results demonstrate the utility of a cone-dominant rodent model for advancing the clinical translation of cell replacement therapies.
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Affiliation(s)
- Ching Tzu Yu
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sangeetha Kandoi
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Ramesh Periasamy
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - L Vinod K Reddy
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Hannah M Follett
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Phyllis Summerfelt
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Cassandra Martinez
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA
| | - Chloe Guillaume
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; School of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Owen Bowie
- School of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Thomas B Connor
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Daniel M Lipinski
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Kenneth P Allen
- Department of Microbiology and Immunology, Biomedical Resource Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Dana K Merriman
- Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, WI, USA
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Deepak A Lamba
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA.
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3
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Zhang J, Sabarinathan R, Bubel T, Jia W, Williams DR, Hunter JJ. Spectral Dependence of Light Exposure on Retinal Pigment Epithelium Disruption in Living Primate Retina. Invest Ophthalmol Vis Sci 2024; 65:43. [PMID: 38416456 PMCID: PMC10910637 DOI: 10.1167/iovs.65.2.43] [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: 02/28/2023] [Accepted: 11/21/2023] [Indexed: 02/29/2024] Open
Abstract
Purpose RPE disruption with light exposures below or close to the American National Standards Institute (ANSI) photochemical maximum permissible exposure (MPE) have been observed, but these findings were limited to two wavelengths. We have extended the measurements across the visible spectrum. Methods Retinal imaging with fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO) was used to provide an in vivo measure of RPE disruption at a cellular level. The threshold retinal radiant exposures (RREs) for RPE disruption (localized detectable change in the fluorescence image) were determined at 460, 476, 488, 530, 543, 561, 594, 632, and 671 nm (uniform 0.5° square exposure) using multiples locations in 4 macaques. Results FAOSLO is sensitive in detecting RPE disruption. The visible light action spectrum dependence for RPE disruption with continuous wave (CW) extended field exposures was determined. It has a shallower slope than the current ANSI blue-light hazard MPE. At all wavelengths beyond 530 nm, the disruption threshold is below the ANSI blue-light hazard MPE. There is reciprocity of exposure irradiance and duration for exposures at 460 and 594 nm. Conclusions We measured with FAOSLO the action spectrum dependence for photochemical RPE disruption across the visible light spectrum. Using this in vivo measure of phototoxicity provided by FAOSLO, we find that thresholds are lower than previously measured. The wavelength dependence in our data is considerably shallower than the spectral dependence of the traditional ANSI blue-light hazard, emphasizing the need for more caution with increasing wavelength than expected.
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Affiliation(s)
- Jie Zhang
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Robotrak Technologies, Nanjing, Jiangsu, China
| | - Ranjani Sabarinathan
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Tracy Bubel
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Wuao Jia
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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4
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Moon B, Poletti M, Roorda A, Tiruveedhula P, Liu SH, Linebach G, Rucci M, Rolland JP. Alignment, calibration, and validation of an adaptive optics scanning laser ophthalmoscope for high-resolution human foveal imaging. APPLIED OPTICS 2024; 63:730-742. [PMID: 38294386 PMCID: PMC11062499 DOI: 10.1364/ao.504283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/26/2023] [Indexed: 02/01/2024]
Abstract
In prior art, advances in adaptive optics scanning laser ophthalmoscope (AOSLO) technology have enabled cones in the human fovea to be resolved in healthy eyes with normal vision and low to moderate refractive errors, providing new insight into human foveal anatomy, visual perception, and retinal degenerative diseases. These high-resolution ophthalmoscopes require careful alignment of each optical subsystem to ensure diffraction-limited imaging performance, which is necessary for resolving the smallest foveal cones. This paper presents a systematic and rigorous methodology for building, aligning, calibrating, and testing an AOSLO designed for imaging the cone mosaic of the central fovea in humans with cellular resolution. This methodology uses a two-stage alignment procedure and thorough system testing to achieve diffraction-limited performance. Results from retinal imaging of healthy human subjects under 30 years of age with refractive errors of less than 3.5 diopters using either 680 nm or 840 nm light show that the system can resolve cones at the very center of the fovea, the region where the cones are smallest and most densely packed.
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Affiliation(s)
- Benjamin Moon
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Martina Poletti
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, USA
- Department of Neuroscience, University of Rochester, Rochester, NY 14627, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA 94720, USA
| | - Pavan Tiruveedhula
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA 94720, USA
| | - Soh Hang Liu
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Glory Linebach
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Michele Rucci
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY 14627, USA
| | - Jannick P. Rolland
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
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5
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Kaushik V, Dąbrowski M, Gessa L, Kumar N, Fernandes H. Two-photon excitation fluorescence in ophthalmology: safety and improved imaging for functional diagnostics. Front Med (Lausanne) 2024; 10:1293640. [PMID: 38235268 PMCID: PMC10791900 DOI: 10.3389/fmed.2023.1293640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/11/2023] [Indexed: 01/19/2024] Open
Abstract
Two-photon excitation fluorescence (TPEF) is emerging as a powerful imaging technique with superior penetration power in scattering media, allowing for functional imaging of biological tissues at a subcellular level. TPEF is commonly used in cancer diagnostics, as it enables the direct observation of metabolism within living cells. The technique is now widely used in various medical fields, including ophthalmology. The eye is a complex and delicate organ with multiple layers of different cell types and tissues. Although this structure is ideal for visual perception, it generates aberrations in TPEF eye imaging. However, adaptive optics can now compensate for these aberrations, allowing for improved imaging of the eyes of animal models for human diseases. The eye is naturally built to filter out harmful wavelengths, but these wavelengths can be mimicked and thereby utilized in diagnostics via two-photon (2Ph) excitation. Recent advances in laser-source manufacturing have made it possible to minimize the exposure of in vivo measurements within safety, while achieving sufficient signals to detect for functional images, making TPEF a viable option for human application. This review explores recent advances in wavefront-distortion correction in animal models and the safety of use of TPEF on human subjects, both of which make TPEF a potentially powerful tool for ophthalmological diagnostics.
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Affiliation(s)
- Vineeta Kaushik
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Michał Dąbrowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Luca Gessa
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Nelam Kumar
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Humberto Fernandes
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
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Różanowska MB. Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina. Antioxidants (Basel) 2023; 12:2111. [PMID: 38136230 PMCID: PMC10740933 DOI: 10.3390/antiox12122111] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.
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Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, Wales, UK;
- Cardiff Institute for Tissue Engineering and Repair (CITER), Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
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7
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Sabesan R, Grieve K, Hammer DX, Ji N, Marcos S. Introduction to the Feature Issue on Adaptive Optics for Biomedical Applications. BIOMEDICAL OPTICS EXPRESS 2023; 14:1772-1776. [PMID: 37078031 PMCID: PMC10110319 DOI: 10.1364/boe.488044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Indexed: 05/03/2023]
Abstract
The guest editors introduce a feature issue commemorating the 25th anniversary of adaptive optics in biomedical research.
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Affiliation(s)
- Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - 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
| | - Daniel X. Hammer
- Center for Devices and Radiological Health (CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, MD 20993, USA
| | - Na Ji
- Department of Physics, Department of Molecular & Cellular Biology, University of California, Berkeley, CA 94720, USA
| | - Susana Marcos
- Visual Optics and Biophotonics Laboratory, Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Calle Serrano 121, Madrid, 28006, Spain
- Center for Visual Sciences; The Institute of Optics and Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
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8
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Palczewska G, Wojtkowski M, Palczewski K. From mouse to human: Accessing the biochemistry of vision in vivo by two-photon excitation. Prog Retin Eye Res 2023; 93:101170. [PMID: 36787681 PMCID: PMC10463242 DOI: 10.1016/j.preteyeres.2023.101170] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023]
Abstract
The eye is an ideal organ for imaging by a multi-photon excitation approach, because ocular tissues such as the sclera, cornea, lens and neurosensory retina, are highly transparent to infrared (IR) light. The interface between the retina and the retinal pigment epithelium (RPE) is especially informative, because it reflects the health of the visual (retinoid) cycle and its changes in response to external stress, genetic manipulations, and drug treatments. Vitamin A-derived retinoids, like retinyl esters, are natural fluorophores that respond to multi-photon excitation with near IR light, bypassing the filter-like properties of the cornea, lens, and macular pigments. Also, during natural aging some retinoids form bisretinoids, like diretinoid-pyridiniumethanolamine (A2E), that are highly fluorescent. These bisretinoids appear to be elevated concurrently with aging. Vitamin A-derived retinoids and bisretinoidss are detected by two-photon ophthalmoscopy (2PO), using a new class of light sources with adjustable spatial, temporal, and spectral properties. Furthermore, the two-photon (2P) absorption of IR light by the visual pigments in rod and cone photoreceptors can initiate visual transduction by cis-trans isomerization of retinal, enabling parallel functional studies. Recently we overcame concerns about safety, data interpretation and complexity of the 2P-based instrumentation, the major roadblocks toward advancing this modality to the clinic. These imaging and retina-function assessment advancements have enabled us to conduct the first 2P studies with humans.
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Affiliation(s)
- Grazyna Palczewska
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA; International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland; Polgenix, Inc., Department of Medical Devices, Cleveland, OH, USA; Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.
| | - Maciej Wojtkowski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland; Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland; Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland.
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, USA; Department of Physiology & Biophysics, School of Medicine, And Chemistry, Molecular Biology and Biochemistry, University of California, Irvine, CA, USA.
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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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Louey A, Hernández D, Pébay A, Daniszewski M. Automation of Organoid Cultures: Current Protocols and Applications. SLAS DISCOVERY 2021; 26:1138-1147. [PMID: 34167363 DOI: 10.1177/24725552211024547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GRAPHICAL ABSTRACT [Formula: see text].
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Affiliation(s)
- Alexandra Louey
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Damián Hernández
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Alice Pébay
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, Australia.,Department of Surgery, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Maciej Daniszewski
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, Victoria, Australia
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11
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Ringel MJ, Tang EM, Tao YK. Advances in multimodal imaging in ophthalmology. Ther Adv Ophthalmol 2021; 13:25158414211002400. [PMID: 35187398 PMCID: PMC8855415 DOI: 10.1177/25158414211002400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
Multimodality ophthalmic imaging systems aim to enhance the contrast, resolution, and functionality of existing technologies to improve disease diagnostics and therapeutic guidance. These systems include advanced acquisition and post-processing methods using optical coherence tomography (OCT), combined scanning laser ophthalmoscopy and OCT systems, adaptive optics, surgical guidance, and photoacoustic technologies. Here, we provide an overview of these ophthalmic imaging systems and their clinical and basic science applications.
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Affiliation(s)
- Morgan J. Ringel
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Eric M. Tang
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Yuankai K. Tao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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12
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Schweitzer D, Haueisen J, Brauer JL, Hammer M, Klemm M. Comparison of algorithms to suppress artifacts from the natural lens in fluorescence lifetime imaging ophthalmoscopy (FLIO). BIOMEDICAL OPTICS EXPRESS 2020; 11:5586-5602. [PMID: 33149973 PMCID: PMC7587265 DOI: 10.1364/boe.400059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/08/2020] [Accepted: 08/08/2020] [Indexed: 06/11/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) has developed as a new diagnostic tool in ophthalmology. FLIO measurements are taken from 30° retinal fields in two spectral channels (short spectral channel (SSC): 498-560 nm, long spectral channel (LSC): 560-720 nm). Because of the layered structure of the eye, the detected signal is an interaction of the fluorescence decay of the anterior part and of the fundus. By comparing FLIO measurements before and after cataract surgery, the impact of the natural lens was proven, despite the application of a confocal laser scanning (cSLO) technique. The goal of this work was to determine the best algorithmic solution to isolate the sole fundus fluorescence lifetime from the measured signal, suppressing artifacts from the natural lens. Three principles based on a tri-exponential model were investigated: a tailfit, a layer-based approach with a temporally shifted component, and the inclusion of a separately measured fluorescence decay of the natural lens. The mean fluorescence lifetime τm,12 is calculated using only the shortest and the intermediate exponential component. τm,all is calculated using all three exponential components. The results of tri-exponential tailfit after cataract surgery were considered as a reference, because the implanted artificial lens can be assumed as non-fluorescent. In SSC, the best accordance of τm,all of the reference was determined with τm,12 of the tailfit before surgery. If high-quality natural lens measurements are available, the correspondence of τm,12 is best with τm,all of the reference. In LSC, there is a good accordance for all models between τm,12 before and after surgery. To study the pure fundus fluorescence decay in eyes with natural lenses, we advise to utilize fluorescence lifetime τm,12 of a triple-exponential tailfit, as it corresponds well with the mean fluorescence lifetime τm,all of eyes with fluorescence-less artificial intraocular lenses.
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Affiliation(s)
- D. Schweitzer
- Department of Ophthalmology, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - J. Haueisen
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
| | - J. L. Brauer
- Department of Ophthalmology, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - M. Hammer
- Department of Ophthalmology, University Hospital Jena, Am Klinikum 1, 07747 Jena, Germany
| | - M. Klemm
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
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13
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Bueno JM, Cruz-Castillo R, Avilés-Trigueros M, Bautista-Elivar N. Arrangement of the photoreceptor mosaic in a diabetic rat model imaged with multiphoton microscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:4901-4914. [PMID: 33014589 PMCID: PMC7510868 DOI: 10.1364/boe.399835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
Diabetic retinopathy (DR) is defined as a microvascular pathology. However, some data have suggested that the retinal photoreceptors (PRs) might be important in the pathogenesis of this ocular disease. In this study the organization of the PRs in control and diabetic-induced rats was compared using multiphoton microscopy. The PR mosaic was imaged at different locations in non-stained retinas. The density of PRs was directly quantified from cell counting. The spatially resolved density presents a double-slope pattern (from the central retina towards the periphery) in both healthy and pathological samples, although the values for the latter were significantly lower all across the retina. Moreover, Voronoi analysis was performed to explore changes in PR topography. In control specimens a hexagonally packed structure was dominant. However, despite the non-controlled effects of the disease in retinal structures, this PR regularity was fairly maintained in diabetic retinas.
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Affiliation(s)
- Juan M. Bueno
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Murcia, Spain
| | - Ricardo Cruz-Castillo
- Área Académica de Matemáticas y Física, Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Hidalgo, Mexico
| | - Marcelino Avilés-Trigueros
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia e Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, “Campus Mare Nostrum” de Excelencia International, Murcia, Spain
| | - Nazario Bautista-Elivar
- Departamento de Ingeniería Eléctrica, Tecnológico Nacional de México, Instituto Tecnológico de Pachuca, Hidalgo, Mexico
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14
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Aboualizadeh E, Phillips MJ, McGregor JE, DiLoreto DA, Strazzeri JM, Dhakal KR, Bateman B, Jager LD, Nilles KL, Stuedemann SA, Ludwig AL, Hunter JJ, Merigan WH, Gamm DM, Williams DR. Imaging Transplanted Photoreceptors in Living Nonhuman Primates with Single-Cell Resolution. Stem Cell Reports 2020; 15:482-497. [PMID: 32707075 PMCID: PMC7419740 DOI: 10.1016/j.stemcr.2020.06.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022] Open
Abstract
Stem cell-based transplantation therapies offer hope for currently untreatable retinal degenerations; however, preclinical progress has been largely confined to rodent models. Here, we describe an experimental platform for accelerating photoreceptor replacement therapy in the nonhuman primate, which has a visual system much more similar to the human. We deployed fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO) to noninvasively track transplanted photoreceptor precursors over time at cellular resolution in the living macaque. Fluorescently labeled photoreceptors generated from a CRX+/tdTomato human embryonic stem cell (hESC) reporter line were delivered subretinally to macaques with normal retinas and following selective ablation of host photoreceptors using an ultrafast laser. The fluorescent reporter together with FAOSLO allowed transplanted photoreceptor precursor survival, migration, and neurite formation to be monitored over time in vivo. Histological examination suggested migration of photoreceptor precursors to the outer plexiform layer and potential synapse formation in ablated areas in the macaque eye.
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Affiliation(s)
| | - M Joseph Phillips
- Waisman Center, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA
| | | | - David A DiLoreto
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Jennifer M Strazzeri
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Kamal R Dhakal
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Brittany Bateman
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | | | - Kelsy L Nilles
- Waisman Center, University of Wisconsin, Madison, WI, USA
| | | | | | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA; The Institute of Optics, 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
| | - David M Gamm
- Waisman Center, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA; The Institute of Optics, University of Rochester, Rochester, NY, USA.
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15
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Qin Z, He S, Yang C, Yung JSY, Chen C, Leung CKS, Liu K, Qu JY. Adaptive optics two-photon microscopy enables near-diffraction-limited and functional retinal imaging in vivo. LIGHT, SCIENCE & APPLICATIONS 2020; 9:79. [PMID: 32411364 PMCID: PMC7203252 DOI: 10.1038/s41377-020-0317-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/11/2020] [Accepted: 04/15/2020] [Indexed: 05/08/2023]
Abstract
In vivo fundus imaging offers non-invasive access to neuron structures and biochemical processes in the retina. However, optical aberrations of the eye degrade the imaging resolution and prevent visualization of subcellular retinal structures. We developed an adaptive optics two-photon excitation fluorescence microscopy (AO-TPEFM) system to correct ocular aberrations based on a nonlinear fluorescent guide star and achieved subcellular resolution for in vivo fluorescence imaging of the mouse retina. With accurate wavefront sensing and rapid aberration correction, AO-TPEFM permits structural and functional imaging of the mouse retina with submicron resolution. Specifically, simultaneous functional calcium imaging of neuronal somas and dendrites was demonstrated. Moreover, the time-lapse morphological alteration and dynamics of microglia were characterized in a mouse model of retinal disorder. In addition, precise laser axotomy was achieved, and degeneration of retinal nerve fibres was studied. This high-resolution AO-TPEFM is a promising tool for non-invasive retinal imaging and can facilitate the understanding of a variety of eye diseases as well as neurodegenerative disorders in the central nervous system.
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Affiliation(s)
- Zhongya Qin
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Sicong He
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Chao Yang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jasmine Sum-Yee Yung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Congping Chen
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | | | - Kai Liu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianan Y. Qu
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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16
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Huckenpahler AL, Carroll J, Salmon AE, Sajdak BS, Mastey RR, Allen KP, Kaplan HJ, McCall MA. Noninvasive Imaging and Correlative Histology of Cone Photoreceptor Structure in the Pig Retina. Transl Vis Sci Technol 2019; 8:38. [PMID: 31867139 PMCID: PMC6922271 DOI: 10.1167/tvst.8.6.38] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 10/04/2019] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To evaluate different methods of studying cone photoreceptor structure in wild-type (WT) and transgenic pigs carrying the human rhodopsin P23H mutant gene (TgP23H). METHODS For in vivo imaging, pigs were anesthetized with tiletamine-zolazepam and isoflurane and given lidocaine-bupivacaine retrobulbar injections. Stay sutures and a custom head mount were used to hold and steer the head for adaptive optics scanning light ophthalmoscopy (AOSLO). Six WT and TgP23H littermates were imaged at postnatal day 30 (P30), P90, and P180 with AOSLO and optical coherence tomography (OCT), and two additional sets of littermates were imaged at P3 and P15 with OCT only. AOSLO imaging and correlative differential interference contrast microscopy were performed on a P240 WT pig and on WT and TgP23H littermates at P30 and P180. RESULTS AOSLO cone density generally underestimates histology density (mean difference ± SD = 24.8% ± 21.4%). The intensity of the outer retinal hyperreflective OCT band attributed to photoreceptors is attenuated in TgP23H pigs at all ages. In contrast, AOSLO images show cones that retain inner and outer segments through P180. At retinal locations outside the visual streak, TgP23H pigs show a heterogeneous degenerating cone mosaic by using two criteria: variable contrast on a split detector AOSLO and high reflectivity on a confocal AOSLO. CONCLUSIONS AOSLO reveals that the cone mosaic is similar to ex vivo histology. Its use as a noninvasive tool will enable observation of morphologic changes that arise in the cone mosaic of TgP23H pigs over time. TRANSLATIONAL RELEVANCE Pigs are widely used for translational studies, and the ability to noninvasively assess cellular changes in the cone mosaic will facilitate more detailed investigations of new retinal disease models as well as outcomes of potential therapies.
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Affiliation(s)
- Alison L Huckenpahler
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, 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
| | - Alexander E Salmon
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Benjamin S Sajdak
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Rebecca R Mastey
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Kenneth P Allen
- Biomedical Resource Center, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Henry J Kaplan
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA
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17
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Cunefare D, Huckenpahler AL, Patterson EJ, Dubra A, Carroll J, Farsiu S. RAC-CNN: multimodal deep learning based automatic detection and classification of rod and cone photoreceptors in adaptive optics scanning light ophthalmoscope images. BIOMEDICAL OPTICS EXPRESS 2019; 10:3815-3832. [PMID: 31452977 PMCID: PMC6701534 DOI: 10.1364/boe.10.003815] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/26/2019] [Accepted: 06/29/2019] [Indexed: 05/03/2023]
Abstract
Quantification of the human rod and cone photoreceptor mosaic in adaptive optics scanning light ophthalmoscope (AOSLO) images is useful for the study of various retinal pathologies. Subjective and time-consuming manual grading has remained the gold standard for evaluating these images, with no well validated automatic methods for detecting individual rods having been developed. We present a novel deep learning based automatic method, called the rod and cone CNN (RAC-CNN), for detecting and classifying rods and cones in multimodal AOSLO images. We test our method on images from healthy subjects as well as subjects with achromatopsia over a range of retinal eccentricities. We show that our method is on par with human grading for detecting rods and cones.
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Affiliation(s)
- David Cunefare
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Alison L. Huckenpahler
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Emily J. Patterson
- 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
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
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18
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Ranawat H, Pal S, Mazumder N. Recent trends in two-photon auto-fluorescence lifetime imaging (2P-FLIM) and its biomedical applications. Biomed Eng Lett 2019; 9:293-310. [PMID: 31456890 PMCID: PMC6694381 DOI: 10.1007/s13534-019-00119-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 05/30/2019] [Accepted: 06/27/2019] [Indexed: 02/07/2023] Open
Abstract
Two photon fluorescence microscopy and the numerous technical advances to it have served as valuable tools in biomedical research. The fluorophores (exogenous or endogenous) absorb light and emit lower energy photons than the absorption energy and the emission (fluorescence) signal is measured using a fluorescence decay graph. Additionally, high spatial resolution images can be acquired in two photon fluorescence lifetime imaging (2P-FLIM) with improved penetration depth which helps in detection of fluorescence signal in vivo. 2P-FLIM is a non-invasive imaging technique in order to visualize cellular metabolic, by tracking intrinsic fluorophores present in it, such as nicotinamide adenine dinucleotide, flavin adenine dinucleotide and tryptophan etc. 2P-FLIM of these molecules enable the visualization of metabolic alterations, non-invasively. This comprehensive review discusses the numerous applications of 2P-FLIM towards cancer, neuro-degenerative, infectious diseases, and wound healing.
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Affiliation(s)
- Harsh Ranawat
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka 576104 India
| | - Sagnik Pal
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka 576104 India
| | - Nirmal Mazumder
- Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka 576104 India
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19
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AbdelAl O, Ashraf M, Sampani K, Sun JK. "For Mass Eye and Ear Special Issue" Adaptive Optics in the Evaluation of Diabetic Retinopathy. Semin Ophthalmol 2019; 34:189-197. [PMID: 31188056 DOI: 10.1080/08820538.2019.1620794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Retinal imaging is a fundamental tool for clinical and research efforts in the evaluation and management of diabetic retinopathy. Adaptive optics (AO) is an imaging technique that enables correction of over 90% of the optical aberrations of an individual eye induced primarily by the tear film, cornea and lens. The two major tasks of any AO system are to measure the optical imperfections of the eye and to then compensate for these aberrations to generate a corrected wavefront of reflected light from the eye. AO scanning laser ophthalmoscopy (AOSLO) provides a theoretical lateral resolution limit of 1.4 μm, allowing the study of microscopic features of the retinal vascular and neural tissue. AOSLO studies have revealed irregularities of the photoreceptor mosaic, vascular loss, and details of vascular lesions in diabetic eyes that may provide new insight into development, regression, and response to therapy of diabetic eye disease.
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Affiliation(s)
- Omar AbdelAl
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
| | - Mohammed Ashraf
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
| | - Konstantina Sampani
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,c Department of Medicine , Harvard Medical School , Boston , MA , USA
| | - Jennifer K Sun
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
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20
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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: 127] [Impact Index Per Article: 25.4] [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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21
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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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22
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Schwarz C, Sharma R, Cheong SK, Keller M, Williams DR, Hunter JJ. Selective S Cone Damage and Retinal Remodeling Following Intense Ultrashort Pulse Laser Exposures in the Near-Infrared. Invest Ophthalmol Vis Sci 2018; 59:5973-5984. [PMID: 30556839 PMCID: PMC6298064 DOI: 10.1167/iovs.18-25383] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/30/2018] [Indexed: 02/06/2023] Open
Abstract
Purpose Infrared ultrashort pulse lasers are becoming increasingly popular for applications in the living eye. However, safety standards are not yet well established. Here we investigate retinal damage close to threshold for this pulse regime in the living macaque eye. Methods Retinal radiant exposures between 214 and 856 J/cm2 were delivered to the photoreceptor layer with an ultrashort pulse laser (730 nm, 55 fs, 80 MHz) through a two-photon adaptive optics scanning light ophthalmoscope. Retinal exposures were followed up immediately after and over several weeks with high-resolution reflectance and two-photon excited fluorescence ophthalmoscopy, providing structural and functional information. Results Retinal radiant exposures of 856 J/cm2 resulted in permanent S cone damage. Immediately after the exposure, the affected cones emitted about 2.6 times less two-photon excited fluorescence (TPEF) and showed an altered TPEF time course. Several weeks after the initial exposure, S cone outer and inner segments had disappeared. The space was filled by rods in the peripheral retina and cones near the fovea. Conclusion Interestingly, S cones are the receptor class with the lowest sensitivity in the near-infrared but are known to be particularly susceptible to ultraviolet and blue light. This effect of selective S cone damage after intense infrared ultrashort pulse laser exposure may be due to nonlinear absorption and distinct from pure thermal and mechanical mechanisms often associated with ultrashort pulse lasers.
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Affiliation(s)
- Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Robin Sharma
- Facebook Reality Labs, Redmond, Washington, United States
| | - Soon Keen Cheong
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Matthew Keller
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- College of Natural Science, Michigan State University, East Lansing, Michigan, United States
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
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23
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Palczewska G, Stremplewski P, Suh S, Alexander N, Salom D, Dong Z, Ruminski D, Choi EH, Sears AE, Kern TS, Wojtkowski M, Palczewski K. Two-photon imaging of the mammalian retina with ultrafast pulsing laser. JCI Insight 2018; 3:121555. [PMID: 30185665 DOI: 10.1172/jci.insight.121555] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022] Open
Abstract
Noninvasive imaging of visual system components in vivo is critical for understanding the causal mechanisms of retinal diseases and for developing therapies for their treatment. However, ultraviolet light needed to excite endogenous fluorophores that participate in metabolic processes of the retina is highly attenuated by the anterior segment of the human eye. In contrast, 2-photon excitation fluorescence imaging with pulsed infrared light overcomes this obstacle. Reducing retinal exposure to laser radiation remains a major barrier in advancing this technology to studies in humans. To increase fluorescence intensity and reduce the requisite laser power, we modulated ultrashort laser pulses with high-order dispersion compensation and applied sensorless adaptive optics and custom image recovery software and observed an over 300% increase in fluorescence of endogenous retinal fluorophores when laser pulses were shortened from 75 fs to 20 fs. No functional or structural changes to the retina were detected after exposure to 2-photon excitation imaging light with 20-fs pulses. Moreover, wide bandwidth associated with short pulses enables excitation of multiple fluorophores with different absorption spectra and thus can provide information about their relative changes and intracellular distribution. These data constitute a substantial advancement for safe 2-photon fluorescence imaging of the human eye.
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Affiliation(s)
| | - Patrycjusz Stremplewski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Susie Suh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nathan Alexander
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - David Salom
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zhiqian Dong
- Polgenix, Inc., Department of Medical Devices, Cleveland, Ohio, USA
| | - Daniel Ruminski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Elliot H Choi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Avery E Sears
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Timothy S Kern
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Maciej Wojtkowski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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Batista A, Breunig HG, König A, Morgado AM, König K. Assessment of the metabolism and morphology of the porcine cornea, lens and retina by 2-photon imaging. JOURNAL OF BIOPHOTONICS 2018; 11:e201700324. [PMID: 29575612 DOI: 10.1002/jbio.201700324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/21/2018] [Indexed: 06/08/2023]
Abstract
Two-photon imaging is a noninvasive imaging technique with increasing importance in the biological and medical fields since it allows intratissue cell imaging with high resolution. We demonstrate the feasibility of using a single 2-photon instrument to evaluate the cornea, the crystalline lens and the retina based on their autofluorescence (AF). Image acquisition was performed using a custom-built 2-photon microscope for 5-dimensional microscopy with a near infrared broadband sub-15 femtosecond laser centered at 800 nanometers. Signals were detected using a spectral photomultiplier tube. The spectral ranges for the analysis of each tissue/layer AF were determined based on the spectra of each tissue as well as of pure endogenous fluorophores. The cornea, lens and retina are characterized at multiple depths with subcellular resolution based on their morphology and AF lifetime. Additionally, the AF lifetime of NAD(P)H was used to assess the metabolic activity of the cornea epithelium, endothelium and keratocytes. The feasibility to evaluate the metabolic activity of lens epithelial cells was also demonstrated, which may be used to further investigate the pathogenesis of cataracts. The results illustrate the potential of multimodal multiphoton imaging as a novel ophthalmologic technique as well as its potential as a diagnostic tool.
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Affiliation(s)
- Ana Batista
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
- JenLab GmbH, Saarbrücken, Germany
| | - Hans G Breunig
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
- JenLab GmbH, Saarbrücken, Germany
| | - Aisada König
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
- JenLab GmbH, Saarbrücken, Germany
| | - António M Morgado
- Department of Physics, University of Coimbra, Coimbra, Portugal
- Coimbra Institute for Biomedical Imaging and Translational Research/Institute of Nuclear Sciences Applied to Heath (CIBIT/ICNAS), University of Coimbra, Coimbra, Portugal
| | - Karsten König
- Biophotonics and Laser Technology, Saarland University, Saarbrücken, Germany
- JenLab GmbH, Saarbrücken, Germany
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Hammer M, Sauer L, Klemm M, Peters S, Schultz R, Haueisen J. Fundus autofluorescence beyond lipofuscin: lesson learned from ex vivo fluorescence lifetime imaging in porcine eyes. BIOMEDICAL OPTICS EXPRESS 2018; 9:3078-3091. [PMID: 29984084 PMCID: PMC6033583 DOI: 10.1364/boe.9.003078] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/25/2018] [Accepted: 04/25/2018] [Indexed: 05/06/2023]
Abstract
Fundus autofluorescence (FAF) imaging is a well-established method in ophthalmology; however, the fluorophores involved need more clarification. The FAF lifetimes of 20 post mortem porcine eyes were measured in two spectral channels using fluorescence lifetime imaging ophthalmoscopy (FLIO) and compared with clinical data from 44 healthy young subjects. The FAF intensity ratio of the short and the long wavelength emission (spectral ratio) was determined. Ex vivo porcine fundus fluorescence emission is generally less intense than that seen in human eyes. The porcine retina showed significantly (p<0.05) longer lifetimes than the retinal pigment epithelium (RPE): 584 ± 128 ps vs. 121 ± 55 ps 498-560 nm, 240 ± 42 ps vs. 125 ± 20 ps at 560-720 nm. Furthermore, the lifetimes of the porcine RPE were significantly shorter (121 ± 55 ps and 125 ± 20 ps) than those measured from human fundus in vivo (162 ± 14 ps and 179 ± 13 ps, respectively). The fluorescence emission of porcine retina was shifted towards a shorter wavelength compared to that of RPE and human FAF. This data shows the considerable contribution of fluorophores in the neural retina to total FAF intensity in porcine eyes.
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Affiliation(s)
- Martin Hammer
- University Hospital Jena, Department of Ophthalmology, 07747 Jena, Am Klinikum 1, Germany
- University of Jena, Center for Biomedical Optics and Photonics, 07740 Jena, Germany
| | - Lydia Sauer
- University Hospital Jena, Department of Ophthalmology, 07747 Jena, Am Klinikum 1, Germany
- Technical University Ilmenau, Institute for Biomedical Engineering and Informatics, Gustav-Kirchhoff-Str. 2, 98693 Ilmenau, Germany
| | - Matthias Klemm
- Technical University Ilmenau, Institute for Biomedical Engineering and Informatics, Gustav-Kirchhoff-Str. 2, 98693 Ilmenau, Germany
| | - Sven Peters
- University Hospital Jena, Department of Ophthalmology, 07747 Jena, Am Klinikum 1, Germany
| | - Rowena Schultz
- University Hospital Jena, Department of Ophthalmology, 07747 Jena, Am Klinikum 1, Germany
| | - Jens Haueisen
- Technical University Ilmenau, Institute for Biomedical Engineering and Informatics, Gustav-Kirchhoff-Str. 2, 98693 Ilmenau, Germany
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Winter S, Sabesan R, Tiruveedhula P, Privitera C, Unsbo P, Lundström L, Roorda A. Transverse chromatic aberration across the visual field of the human eye. J Vis 2017; 16:9. [PMID: 27832270 PMCID: PMC5109981 DOI: 10.1167/16.14.9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The purpose of this study was to measure the transverse chromatic aberration (TCA) across the visual field of the human eye objectively. TCA was measured at horizontal and vertical field angles out to ±15° from foveal fixation in the right eye of four subjects. Interleaved retinal images were taken at wavelengths 543 nm and 842 nm in an adaptive optics scanning laser ophthalmoscope (AOSLO). To obtain true measures of the human eye's TCA, the contributions of the AOSLO system's TCA were measured using an on-axis aligned model eye and subtracted from the ocular data. The increase in TCA was found to be linear with eccentricity, with an average slope of 0.21 arcmin/degree of visual field angle (corresponding to 0.41 arcmin/degree for 430 nm to 770 nm). The absolute magnitude of ocular TCA varied between subjects, but was similar to the resolution acuity at 10° in the nasal visual field, encompassing three to four cones. Therefore, TCA can be visually significant. Furthermore, for high-resolution imaging applications, whether visualizing or stimulating cellular features in the retina, it is important to consider the lateral displacements between wavelengths and the variation in blur over the visual field.
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Affiliation(s)
- Simon Winter
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm,
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | | | | | - Peter Unsbo
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Linda Lundström
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA, USAVision Science Graduate Group, University of California, Berkeley, CA, USA
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Sharma R, Schwarz C, Hunter JJ, Palczewska G, Palczewski K, Williams DR. Formation and Clearance of All-Trans-Retinol in Rods Investigated in the Living Primate Eye With Two-Photon Ophthalmoscopy. Invest Ophthalmol Vis Sci 2017; 58:604-613. [PMID: 28129424 PMCID: PMC5283085 DOI: 10.1167/iovs.16-20061] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Two-photon excited fluorescence (TPEF) imaging has potential as a functional tool for tracking visual pigment regeneration in the living eye. Previous studies have shown that all-trans-retinol is likely the chief source of time-varying TPEF from photoreceptors. Endogenous TPEF from retinol could provide the specificity desired for tracking the visual cycle. However, in vivo characterization of native retinol kinetics is complicated by visual stimulation from the imaging beam. We have developed an imaging scheme for overcoming these challenges and monitored the formation and clearance of retinol. Methods Three macaques were imaged by using an in vivo two-photon ophthalmoscope. Endogenous TPEF was excited at 730 nm and recorded through the eye's pupil for more than 90 seconds. Two-photon excited fluorescence increased with onset of light and plateaued within 40 seconds, at which point, brief incremental stimuli were delivered at 561 nm. The responses of rods to stimulation were analyzed by using first-order kinetics. Results Two-photon excited fluorescence resulting from retinol production corresponded to the fraction of rhodopsin bleached. The photosensitivity of rhodopsin was estimated to be 6.88 ± 5.50 log scotopic troland. The rate of retinol clearance depended on intensity of incremental stimulation. Clearance was faster for stronger stimuli and time constants ranged from 50 to 300 seconds. Conclusions This study demonstrates a method for rapidly measuring the rate of clearance of retinol in vivo. Moreover, TPEF generated due to retinol can be used as a measure of rhodopsin depletion, similar to densitometry. This enhances the utility of two-photon ophthalmoscopy as a technique for evaluating the visual cycle in the living eye.
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Affiliation(s)
- Robin Sharma
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States 2Flaum Eye Institute, University of Rochester, Rochester, New York, United States 3Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States 2Flaum Eye Institute, University of Rochester, Rochester, New York, United States 6The Institute of Optics, University of Rochester, Rochester, New York, United States
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Feeks JA, Hunter JJ. Adaptive optics two-photon excited fluorescence lifetime imaging ophthalmoscopy of exogenous fluorophores in mice. BIOMEDICAL OPTICS EXPRESS 2017; 8:2483-2495. [PMID: 28663886 PMCID: PMC5480493 DOI: 10.1364/boe.8.002483] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 05/05/2023]
Abstract
In vivo cellular scale fluorescence lifetime imaging of the mouse retina has the potential to be a sensitive marker of retinal cell health. In this study, we demonstrate fluorescence lifetime imaging of extrinsic fluorophores using adaptive optics fluorescence lifetime imaging ophthalmoscopy (AOFLIO). We recorded AOFLIO images of inner retinal cells labeled with enhanced green fluorescent protein (EGFP) and capillaries labeled with fluorescein. We demonstrate that AOFLIO can be used to differentiate spectrally overlapping fluorophores in the retina. With further refinements, AOFLIO could be used to assess retinal health in early stages of degeneration by utilizing lifetime-based sensors or even fluorophores native to the retina.
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Affiliation(s)
- James A. Feeks
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY 14620, USA
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, NY 14642, USA
- Department of Biomedical Engineering, University of Rochester, NY 14627, USA
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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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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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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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Laslandes M, Salas M, Hitzenberger CK, Pircher M. Influence of wave-front sampling in adaptive optics retinal imaging. BIOMEDICAL OPTICS EXPRESS 2017; 8:1083-1100. [PMID: 28271004 PMCID: PMC5330566 DOI: 10.1364/boe.8.001083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/11/2017] [Accepted: 01/12/2017] [Indexed: 05/03/2023]
Abstract
A wide range of sampling densities of the wave-front has been used in retinal adaptive optics (AO) instruments, compared to the number of corrector elements. We developed a model in order to characterize the link between number of actuators, number of wave-front sampling points and AO correction performance. Based on available data from aberration measurements in the human eye, 1000 wave-fronts were generated for the simulations. The AO correction performance in the presence of these representative aberrations was simulated for different deformable mirror and Shack Hartmann wave-front sensor combinations. Predictions of the model were experimentally tested through in vivo measurements in 10 eyes including retinal imaging with an AO scanning laser ophthalmoscope. According to our study, a ratio between wavefront sampling points and actuator elements of 2 is sufficient to achieve high resolution in vivo images of photoreceptors.
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Imaging individual neurons in the retinal ganglion cell layer of the living eye. Proc Natl Acad Sci U S A 2017; 114:586-591. [PMID: 28049835 DOI: 10.1073/pnas.1613445114] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Although imaging of the living retina with adaptive optics scanning light ophthalmoscopy (AOSLO) provides microscopic access to individual cells, such as photoreceptors, retinal pigment epithelial cells, and blood cells in the retinal vasculature, other important cell classes, such as retinal ganglion cells, have proven much more challenging to image. The near transparency of inner retinal cells is advantageous for vision, as light must pass through them to reach the photoreceptors, but it has prevented them from being directly imaged in vivo. Here we show that the individual somas of neurons within the retinal ganglion cell (RGC) layer can be imaged with a modification of confocal AOSLO, in both monkeys and humans. Human images of RGC layer neurons did not match the quality of monkey images for several reasons, including safety concerns that limited the light levels permissible for human imaging. We also show that the same technique applied to the photoreceptor layer can resolve ambiguity about cone survival in age-related macular degeneration. The capability to noninvasively image RGC layer neurons in the living eye may one day allow for a better understanding of diseases, such as glaucoma, and accelerate the development of therapeutic strategies that aim to protect these cells. This method may also prove useful for imaging other structures, such as neurons in the brain.
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Schwarz C, Sharma R, Fischer WS, Chung M, Palczewska G, Palczewski K, Williams DR, Hunter JJ. Safety assessment in macaques of light exposures for functional two-photon ophthalmoscopy in humans. BIOMEDICAL OPTICS EXPRESS 2016; 7:5148-5169. [PMID: 28018732 PMCID: PMC5175559 DOI: 10.1364/boe.7.005148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/08/2016] [Accepted: 11/09/2016] [Indexed: 05/18/2023]
Abstract
Two-photon ophthalmoscopy has potential for in vivo assessment of function of normal and diseased retina. However, light safety of the sub-100 fs laser typically used is a major concern and safety standards are not well established. To test the feasibility of safe in vivo two-photon excitation fluorescence (TPEF) imaging of photoreceptors in humans, we examined the effects of ultrashort pulsed light and the required light levels with a variety of clinical and high resolution imaging methods in macaques. The only measure that revealed a significant effect due to exposure to pulsed light within existing safety standards was infrared autofluorescence (IRAF) intensity. No other structural or functional alterations were detected by other imaging techniques for any of the exposures. Photoreceptors and retinal pigment epithelium appeared normal in adaptive optics images. No effect of repeated exposures on TPEF time course was detected, suggesting that visual cycle function was maintained. If IRAF reduction is hazardous, it is the only hurdle to applying two-photon retinal imaging in humans. To date, no harmful effects of IRAF reduction have been detected.
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Affiliation(s)
- Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Robin Sharma
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | | | - Mina Chung
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Jennifer J. Hunter
- 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
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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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Alexander NS, Palczewska G, Stremplewski P, Wojtkowski M, Kern TS, Palczewski K. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina. BIOMEDICAL OPTICS EXPRESS 2016; 7:2671-91. [PMID: 27446697 PMCID: PMC4948621 DOI: 10.1364/boe.7.002671] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/11/2016] [Accepted: 06/11/2016] [Indexed: 05/18/2023]
Abstract
Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [Palczewska G., Nat Med.20, 785 (2014) Sharma R., Biomed. Opt. Express4, 1285 (2013)].
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Affiliation(s)
- Nathan S Alexander
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
| | | | - Patrycjusz Stremplewski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Maciej Wojtkowski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Timothy S Kern
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; Polgenix Inc., 11000 Cedar Ave, Cleveland, Ohio 44106, USA;
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Sharma R, Schwarz C, Williams DR, Palczewska G, Palczewski K, Hunter JJ. In Vivo Two-Photon Fluorescence Kinetics of Primate Rods and Cones. Invest Ophthalmol Vis Sci 2016; 57:647-57. [PMID: 26903225 PMCID: PMC4771186 DOI: 10.1167/iovs.15-17946] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Purpose The retinoid cycle maintains vision by regenerating bleached visual pigment through metabolic events, the kinetics of which have been difficult to characterize in vivo. Two-photon fluorescence excitation has been used previously to track autofluorescence directly from retinoids and pyridines in the visual cycle in mouse and frog retinas, but the mechanisms of the retinoid cycle are not well understood in primates. Methods We developed a two-photon fluorescence adaptive optics scanning light ophthalmoscope dedicated to in vivo imaging in anesthetized macaques. Using pulsed light at 730 nm, two-photon fluorescence was captured from rods and cones during light and dark adaptation through the eye's pupil. Results The fluorescence from rods and cones increased with light exposure but at different rates. During dark adaptation, autofluorescence declined, with cone autofluorescence decreasing approximately 4 times faster than from rods. Rates of autofluorescence decrease in rods and cones were approximately 4 times faster than their respective rates of photopigment regeneration. Also, subsets of sparsely distributed cones were less fluorescent than their neighbors immediately following bleach at 565 nm and they were comparable with the S cone mosaic in density and distribution. Conclusions Although other molecules could be contributing, we posit that these fluorescence changes are mediated by products of the retinoid cycle. In vivo two-photon ophthalmoscopy provides a way to monitor noninvasively stages of the retinoid cycle that were previously inaccessible in the living primate eye. This can be used to assess objectively photoreceptor function in normal and diseased retinas.
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Affiliation(s)
- Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - David R Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States
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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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Meitav N, Ribak EN, Shoham S. Point spread function estimation from projected speckle illumination. LIGHT, SCIENCE & APPLICATIONS 2016; 5:e16048. [PMID: 30167151 PMCID: PMC6059898 DOI: 10.1038/lsa.2016.48] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 11/15/2015] [Accepted: 11/17/2015] [Indexed: 05/05/2023]
Abstract
The resolution of an imaging apparatus is ideally limited by the diffraction properties of the light passing through the system aperture, but in many practical cases, inhomogeneities in the light propagating medium or imperfections in the optics degrade the image resolution. Here we introduce a powerful and practical new approach for estimating the point spread function (PSF) of an imaging system on the basis of PSF Estimation from Projected Speckle Illumination (PEPSI). PEPSI uses the fact that the speckles' phase randomness cancels the effects of the aberrations in the illumination path, thereby providing an objective pattern for measuring the deformation of the imaging path. Using this approach, both wide-field-of-view and local-PSF estimation can be obtained by calibration-free, single-speckle-pattern projection. Finally, we demonstrate the feasibility of using PEPSI estimates for resolution improvement in iterative maximum likelihood deconvolution.
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Affiliation(s)
- Nizan Meitav
- Department of Biomedical Engineering, Technion—Israel Institute of Technology, Technion City, Haifa 32000, Israel
- Department of Physics, Technion—Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Erez N Ribak
- Department of Physics, Technion—Israel Institute of Technology, Technion City, Haifa 32000, Israel
| | - Shy Shoham
- Department of Biomedical Engineering, Technion—Israel Institute of Technology, Technion City, Haifa 32000, Israel
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40
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Sharma R, Williams DR, Palczewska G, Palczewski K, Hunter JJ. Two-Photon Autofluorescence Imaging Reveals Cellular Structures Throughout the Retina of the Living Primate Eye. Invest Ophthalmol Vis Sci 2016; 57:632-46. [PMID: 26903224 PMCID: PMC4771181 DOI: 10.1167/iovs.15-17961] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 12/30/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Although extrinsic fluorophores can be introduced to label specific cell types in the retina, endogenous fluorophores, such as NAD(P)H, FAD, collagen, and others, are present in all retinal layers. These molecules are a potential source of optical contrast and can enable noninvasive visualization of all cellular layers. We used a two-photon fluorescence adaptive optics scanning light ophthalmoscope (TPF-AOSLO) to explore the native autofluorescence of various cell classes spanning several layers in the unlabeled retina of a living primate eye. METHODS Three macaques were imaged on separate occasions using a custom TPF-AOSLO. Two-photon fluorescence was evoked by pulsed light at 730 and 920 nm excitation wavelengths, while fluorescence emission was collected in the visible range from several retinal layers and different locations. Backscattered light was recorded simultaneously in confocal modality and images were postprocessed to remove eye motion. RESULTS All retinal layers yielded two-photon signals and the heterogeneous distribution of fluorophores provided optical contrast. Several structural features were observed, such as autofluorescence from vessel walls, Müller cell processes in the nerve fibers, mosaics of cells in the ganglion cell and other nuclear layers of the inner retina, as well as photoreceptor and RPE layers in the outer retina. CONCLUSIONS This in vivo survey of two-photon autofluorescence throughout the primate retina demonstrates a wider variety of structural detail in the living eye than is available through conventional imaging methods, and broadens the use of two-photon imaging of normal and diseased eyes.
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Affiliation(s)
- Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
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Abstract
This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye.
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Kusnyerik A, Rozsa B, Veress M, Szabo A, Nemeth J, Maak P. Modeling of in vivo acousto-optic two-photon imaging of the retina in the human eye. OPTICS EXPRESS 2015; 23:23436-23449. [PMID: 26368444 DOI: 10.1364/oe.23.023436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Our aim is to establish a novel combined acousto-optical method for in vivo imaging of the human retina with the two-photon microscope. In this paper we present modeling results based on eye model samples constructed with parameters measured on patients. We used effectively the potential of the electronic compensation offered by the acousto-optic lenses to avoid the use of adaptive optical correction. Simulation predicted lateral resolution between 1.6 µm and 3 µm on the retina. This technology allows the visualization of single cells and promises real time measuring of neural activity in individual neurons, neural segments and cell assemblies with 30-100 µs temporal and subcellular spatial resolution.
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Stremplewski P, Komar K, Palczewski K, Wojtkowski M, Palczewska G. Periscope for noninvasive two-photon imaging of murine retina in vivo. BIOMEDICAL OPTICS EXPRESS 2015; 6:3352-61. [PMID: 26417507 PMCID: PMC4574663 DOI: 10.1364/boe.6.003352] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/01/2015] [Accepted: 08/02/2015] [Indexed: 05/18/2023]
Abstract
Two-photon microscopy allows visualization of subcellular structures in the living animal retina. In previously reported experiments it was necessary to apply a contact lens to each subject. Extending this technology to larger animals would require fitting a custom contact lens to each animal and cumbersome placement of the living animal head on microscope stage. Here we demonstrate a new device, periscope, for coupling light energy into mouse eye and capturing emitted fluorescence. Using this periscope we obtained images of the RPE and their subcellular organelles, retinosomes, with larger field of view than previously reported. This periscope provides an interface with a commercial microscope, does not require contact lens and its design could be modified to image retina in larger animals.
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Affiliation(s)
- Patrycjusz Stremplewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Katarzyna Komar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
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Endophenotypes for Age-Related Macular Degeneration: Extending Our Reach into the Preclinical Stages of Disease. J Clin Med 2015; 3:1335-56. [PMID: 25568804 PMCID: PMC4284143 DOI: 10.3390/jcm3041335] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The key to reducing the individual and societal burden of age-related macular degeneration (AMD)-related vision loss, is to be able to initiate therapies that slow or halt the progression at a point that will yield the maximum benefit while minimizing personal risk and cost. There is a critical need to find clinical markers that, when combined with the specificity of genetic testing, will identify individuals at the earliest stages of AMD who would benefit from preventive therapies. These clinical markers are endophenotypes for AMD, present in those who are likely to develop AMD, as well as in those who have clinical evidence of AMD. Clinical characteristics associated with AMD may also be possible endophenotypes if they can be detected before or at the earliest stages of the condition, but we and others have shown that this may not always be valid. Several studies have suggested that dynamic changes in rhodopsin regeneration (dark adaptation kinetics and/or critical flicker fusion frequencies) may be more subtle indicators of AMD-associated early retinal dysfunction. One can test for the relevance of these measures using genetic risk profiles based on known genetic risk variants. These functional measures may improve the sensitivity and specificity of predictive models for AMD and may also serve to delineate clinical subtypes of AMD that may differ with respect to prognosis and treatment.
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45
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Orban T, Johnson WM, Dong Z, Maeda T, Maeda A, Sakai T, Tsuneoka H, Mieyal JJ, Palczewski K. Serum levels of lipid metabolites in age-related macular degeneration. FASEB J 2015; 29:4579-88. [PMID: 26187344 DOI: 10.1096/fj.15-275289] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/06/2015] [Indexed: 01/24/2023]
Abstract
Age-related macular degeneration (AMD) is a neurodegenerative disease that causes adult-onset blindness. There are 2 forms of this progressive disease: wet and dry. Currently there is no cure for AMD, but several treatment options have started to emerge making early detection critical for therapeutic success. Analysis of the eyes of Abca4(-/-)Rdh8(-/-) mice that display light-induced retinal degeneration indicates that 11-cis-retinal and docosahexaenoic acid (DHA) levels were significantly decreased as compared with the eyes of control dark-adapted C57BL/6J mice. In addition, exposure to intense light correlated with higher levels of prostaglandin G2 in the eyes of Abca4(-/-)Rdh8(-/-) mice. Intense light exposure also lowered DHA levels in the eyes of wild-type C57BL/6J mice without discernible retinal degeneration. Analysis of human serum from patients with AMD recapitulated these dysregulated DHA levels and revealed dysregulation of arachidonic acid (AA) levels as well (∼32% increase in patients with AMD compared with average levels in healthy individuals). From these observations, we then built a statistical model that included levels of DHA and AA from human serum. This model had a 74% probability of correctly identifying patients with AMD from controls. Addition of a genetic analysis for one of the most prevalent amino acid substitutions in the age-related maculopathy susceptibility 2 gene linked to AMD, Ala(69)→Ser, did not improve the statistical model. Thus, we have characterized a reliable method with the potential to detect AMD without a genetic component, paving the way for a larger-scale clinical evaluation. Our studies on mouse models along with the analysis of human serum suggest that our small molecule-based model may serve as an effective tool to estimate the risk of developing AMD.
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Affiliation(s)
- Tivadar Orban
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - William M Johnson
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Zhiqian Dong
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Tadao Maeda
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Akiko Maeda
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Tsutomu Sakai
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Hiroshi Tsuneoka
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - John J Mieyal
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- *Department of Pharmacology and Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA; Polgenix, Incorporated, Cleveland, Ohio, USA; Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; and Louis Stokes Veterans Affairs Medical Research Center, Cleveland, Ohio, USA
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Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
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47
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Masella BD, Hunter JJ, Williams DR. New wrinkles in retinal densitometry. Invest Ophthalmol Vis Sci 2014; 55:7525-34. [PMID: 25316726 PMCID: PMC4244068 DOI: 10.1167/iovs.13-13795] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 09/30/2014] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact. METHODS An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514-nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared. RESULTS We identified stimulus-related fluctuations in 794-nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (animal 1: 0.073 ± 0.006, animal 2: 0.032 ± 0.003). CONCLUSIONS These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function.
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Affiliation(s)
- Benjamin D. Masella
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
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48
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Masella BD, Hunter JJ, Williams DR. Rod photopigment kinetics after photodisruption of the retinal pigment epithelium. Invest Ophthalmol Vis Sci 2014; 55:7535-44. [PMID: 25316724 DOI: 10.1167/iovs.13-13796] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Advances in retinal imaging have led to the discovery of long-lasting retinal changes caused by light exposures below published safety limits, including disruption of the RPE. To investigate the functional consequences of RPE disruption, we combined adaptive optics ophthalmoscopy with retinal densitometry. METHODS A modified adaptive optics scanning light ophthalmoscope (AOSLO) measured the apparent density and regeneration rate of rhodopsin in two macaques before and after four different 568-nm retinal radiant exposures (RREs; 400-3200 J/cm(2)). Optical coherence tomography (OCT) was used to measure the optical path length through the photoreceptor outer segments before and after RPE disruption. RESULTS All tested RREs caused visible RPE disruption. Apparent rhodopsin density was significantly reduced following 1600 (P = 0.01) and 3200 J/cm(2) (P = 0.007) exposures. No significant change in apparent density was observed in response to 800 J/cm(2). Surprisingly, exposure to 400 J/cm(2) showed a significant increase in apparent density (P = 0.047). Rhodopsin recovery rate was not significantly affected by these RREs. Optical coherence tomography measurements showed a significant decrease in the optical path length through the photoreceptor outer segments for RREs above 800 J/cm(2) (P < 0.001). CONCLUSIONS At higher RREs, optical path length through the outer segments was reduced. However, the rate of photopigment regeneration was unchanged. While some ambiguity remains as to the correlation between measured reflectivity and absolute rhodopsin density; at the lowest RREs, RPE disruption appears not to be accompanied by a loss of apparent rhodopsin density, which would have been indicative of functional loss.
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Affiliation(s)
- Benjamin D Masella
- The Institute of Optics, University of Rochester, Rochester, New York, United States Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - David R Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
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49
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Sulai YN, Dubra A. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope. BIOMEDICAL OPTICS EXPRESS 2014; 5:3059-73. [PMID: 25401020 PMCID: PMC4230870 DOI: 10.1364/boe.5.003059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 08/01/2014] [Accepted: 08/04/2014] [Indexed: 05/02/2023]
Abstract
The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.
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Affiliation(s)
- Yusufu N. Sulai
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 USA
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53223, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53223, USA
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50
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Palczewska G, Dong Z, Golczak M, Hunter JJ, Williams DR, Alexander NS, Palczewski K. Noninvasive two-photon microscopy imaging of mouse retina and retinal pigment epithelium through the pupil of the eye. Nat Med 2014; 20:785-9. [PMID: 24952647 PMCID: PMC4087080 DOI: 10.1038/nm.3590] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 11/12/2013] [Indexed: 12/11/2022]
Abstract
Two-photon excitation microscopy can image retinal molecular processes in vivo. Intrinsically fluorescent retinyl esters in subcellular structures called retinosomes are an integral part of the visual chromophore regeneration pathway. Fluorescent condensation products of all-trans-retinal accumulate in the eye with age and are also associated with age-related macular degeneration (AMD). Here, we report repetitive, dynamic imaging of these compounds in live mice through the pupil of the eye. By leveraging advanced adaptive optics, we developed a data acquisition algorithm that permitted the identification of retinosomes and condensation products in the retinal pigment epithelium by their characteristic localization, spectral properties and absence in genetically modified or drug-treated mice. This imaging approach has the potential to detect early molecular changes in retinoid metabolism that trigger light- and AMD-induced retinal defects and to assess the effectiveness of treatments for these conditions.
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Affiliation(s)
| | | | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Jennifer J Hunter
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] Flaum Eye Institute, University of Rochester, Rochester, New York, USA. [3] Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - David R Williams
- 1] Center for Visual Science, University of Rochester, Rochester, New York, USA. [2] The Institute of Optics, University of Rochester, Rochester, New York, USA
| | - Nathan S Alexander
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- 1] Polgenix, Cleveland, Ohio, USA. [2] Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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