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Hegde KR, Ray K, Szmacinski H, Sorto S, Puche AC, Lengyel I, Thompson RB. Two-Photon Excited Fluorescence Lifetime Imaging of Tetracycline-Labeled Retinal Calcification. SENSORS (BASEL, SWITZERLAND) 2023; 23:6626. [PMID: 37514920 PMCID: PMC10386431 DOI: 10.3390/s23146626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/14/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
Deposition of calcium-containing minerals such as hydroxyapatite and whitlockite in the subretinal pigment epithelial (sub-RPE) space of the retina is linked to the development of and progression to the end-stage of age-related macular degeneration (AMD). AMD is the most common eye disease causing blindness amongst the elderly in developed countries; early diagnosis is desirable, particularly to begin treatment where available. Calcification in the sub-RPE space is also directly linked to other diseases such as Pseudoxanthoma elasticum (PXE). We found that these mineral deposits could be imaged by fluorescence using tetracycline antibiotics as specific stains. Binding of tetracyclines to the minerals was accompanied by increases in fluorescence intensity and fluorescence lifetime. The lifetimes for tetracyclines differed substantially from the known background lifetime of the existing natural retinal fluorophores, suggesting that calcification could be visualized by lifetime imaging. However, the excitation wavelengths used to excite these lifetime changes were generally shorter than those approved for retinal imaging. Here, we show that tetracycline-stained drusen in post mortem human retinas may be imaged by fluorescence lifetime contrast using multiphoton (infrared) excitation. For this pilot study, ten eyes from six anonymous deceased donors (3 female, 3 male, mean age 83.7 years, range 79-97 years) were obtained with informed consent from the Maryland State Anatomy Board with ethical oversight and approval by the Institutional Review Board.
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Affiliation(s)
- Kavita R Hegde
- Department of Natural Sciences, Coppin State University, Baltimore, MD 21216, USA
| | - Krishanu Ray
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Henryk Szmacinski
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sharon Sorto
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Adam C Puche
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Imre Lengyel
- The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, UK
| | - Richard B Thompson
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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2
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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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3
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Huynh KT, Walters S, Foley EK, Hunter JJ. Separate lifetime signatures of macaque S cones, M/L cones, and rods observed with adaptive optics fluorescence lifetime ophthalmoscopy. Sci Rep 2023; 13:2456. [PMID: 36774443 PMCID: PMC9922306 DOI: 10.1038/s41598-023-28877-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 01/25/2023] [Indexed: 02/13/2023] Open
Abstract
In the retina, several molecules involved in metabolism, the visual cycle, and other roles exhibit intrinsic fluorescence. The overall properties of retinal fluorescence depend on changes to the composition of these molecules and their environmental interactions due to transient functional shifts, especially in disease. This behooves the understanding of the origins and deviations of these properties within the multilayered retina at high lateral and axial resolution. Of particular interest is the fluorescence lifetime, a potential biomarker of function and disease independent of fluorescence intensity that can be measured in the retina with adaptive optics fluorescence lifetime ophthalmoscopy (AOFLIO). This work demonstrates the utility of the phasor method of analysis, an alternate approach to traditional multiexponential fitting, to evaluate photoreceptor two-photon excited AOFLIO data and separate them based on functional differences. Phasor analysis on fluorescence lifetime decay data allowed the repeatable segregation of S from M/L cones, likely from differences in functional or metabolic demands. Furthermore, it is possible to track the lifetime changes in S cones after photodamage. Phasor analysis increases the sensitivity of AOFLIO to functional differences between cells and has the potential to improve our understanding of pathways involved in normal and diseased conditions at the cellular scale throughout the retina.
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Affiliation(s)
- Khang T Huynh
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA.
- Center for Visual Science, University of Rochester, Rochester, NY, 14642, USA.
| | - Sarah Walters
- Currently with IDEX Health & Science, West Henrietta, NY, 14586, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA
| | - Emma K Foley
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - Jennifer J Hunter
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY, 14642, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
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4
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Schweitzer D, Haueisen J, Klemm M. Suppression of natural lens fluorescence in fundus autofluorescence measurements: review of hardware solutions. BIOMEDICAL OPTICS EXPRESS 2022; 13:5151-5170. [PMID: 36425615 PMCID: PMC9664869 DOI: 10.1364/boe.462559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/25/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO), a technique for investigating metabolic changes in the eye ground, can reveal the first signs of diseases related to metabolism. The fluorescence of the natural lens overlies the fundus fluorescence. Although the influence of natural lens fluorescence can be somewhat decreased with mathematical models, excluding this influence during the measurement by using hardware enables more exact estimation of the fundus fluorescence. Here, we analyze four 1-photon excitation hardware solutions to suppress the influence of natural lens fluorescence: aperture stop separation, confocal scanning laser ophthalmoscopy, combined confocal scanning laser ophthalmoscopy and aperture stop separation, and dual point confocal scanning laser ophthalmoscopy. The effect of each principle is demonstrated in examples. The best suppression is provided by the dual point principle, realized with a confocal scanning laser ophthalmoscope. In this case, in addition to the fluorescence of the whole eye, the fluorescence of the anterior part of the eye is detected from a non-excited spot of the fundus. The intensity and time-resolved fluorescence spectral data of the fundus are derived through the subtraction of the simultaneously measured fluorescence of the excited and non-excited spots. Advantages of future 2-photon fluorescence excitation are also discussed. This study provides the first quantitative evaluation of hardware principles to suppress the fluorescence of the natural lens during measurements of fundus autofluorescence.
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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
| | - M. Klemm
- Institute of Biomedical Engineering and Informatics, POB 100565, 98694 Ilmenau, Germany
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5
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Tang JAH, Granger CE, Kunala K, Parkins K, Huynh KT, Bowles-Johnson K, Yang Q, Hunter JJ. Adaptive optics fluorescence lifetime imaging ophthalmoscopy of in vivo human retinal pigment epithelium. BIOMEDICAL OPTICS EXPRESS 2022; 13:1737-1754. [PMID: 35414970 PMCID: PMC8973160 DOI: 10.1364/boe.451628] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 05/18/2023]
Abstract
The intrinsic fluorescence properties of lipofuscin - naturally occurring granules that accumulate in the retinal pigment epithelium - are a potential biomarker for the health of the eye. A new modality is described here which combines adaptive optics technology with fluorescence lifetime detection, allowing for the investigation of functional and compositional differences within the eye and between subjects. This new adaptive optics fluorescence lifetime imaging ophthalmoscope was demonstrated in 6 subjects. Repeated measurements between visits had a minimum intraclass correlation coefficient of 0.59 Although the light levels were well below maximum permissible exposures, the safety of the imaging paradigm was tested using clinical measures; no concerns were raised. This new technology allows for in vivo adaptive optics fluorescence lifetime imaging of the human RPE mosaic.
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Affiliation(s)
- Janet A. H. Tang
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Contributed equally
| | - Charles E. Granger
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Contributed equally
| | - Karteek Kunala
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Keith Parkins
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Khang T. Huynh
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Kristen Bowles-Johnson
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Qiang Yang
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Jennifer J. Hunter
- 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
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
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6
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Yi M, Wu LC, Du QY, Guan CZ, Liu MD, Li XS, Xiong HL, Tan HS, Wang XH, Zhong JP, Han DA, Wang MY, Zeng YG. Spatiotemporal absorption fluctuation imaging based on U-Net. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:026002. [PMID: 35137573 PMCID: PMC8823698 DOI: 10.1117/1.jbo.27.2.026002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
SIGNIFICANCE Full-field optical angiography is critical for vascular disease research and clinical diagnosis. Existing methods struggle to improve the temporal and spatial resolutions simultaneously. AIM Spatiotemporal absorption fluctuation imaging (ST-AFI) is proposed to achieve dynamic blood flow imaging with high spatial and temporal resolutions. APPROACH ST-AFI is a dynamic optical angiography based on a low-coherence imaging system and U-Net. The system was used to acquire a series of dynamic red blood cell (RBC) signals and static background tissue signals, and U-Net is used to predict optical absorption properties and spatiotemporal fluctuation information. U-Net was generally used in two-dimensional blood flow segmentation as an image processing algorithm for biomedical imaging. In the proposed approach, the network simultaneously analyzes the spatial absorption coefficient differences and the temporal dynamic absorption fluctuation. RESULTS The spatial resolution of ST-AFI is up to 4.33 μm, and the temporal resolution is up to 0.032 s. In vivo experiments on 2.5-day-old chicken embryos were conducted. The results demonstrate that intermittent RBCs flow in capillaries can be resolved, and the blood vessels without blood flow can be suppressed. CONCLUSIONS Using ST-AFI to achieve convolutional neural network (CNN)-based dynamic angiography is a novel approach that may be useful for several clinical applications. Owing to their strong feature extraction ability, CNNs exhibit the potential to be expanded to other blood flow imaging methods for the prediction of the spatiotemporal optical properties with improved temporal and spatial resolutions.
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Affiliation(s)
- Min Yi
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Lin-Chang Wu
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Qian-Yi Du
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Cai-Zhong Guan
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Ming-Di Liu
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Xiao-Song Li
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Hong-Lian Xiong
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Hai-Shu Tan
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Xue-Hua Wang
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Jun-Ping Zhong
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Ding-An Han
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
| | - Ming-Yi Wang
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, Foshan, China
| | - Ya-Guang Zeng
- Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, China
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, China
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7
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Walters S, Feeks JA, Huynh KT, Hunter JJ. Adaptive optics two-photon excited fluorescence lifetime imaging ophthalmoscopy of photoreceptors and retinal pigment epithelium in the living non-human primate eye. BIOMEDICAL OPTICS EXPRESS 2022; 13:389-407. [PMID: 35154879 PMCID: PMC8803039 DOI: 10.1364/boe.444550] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 05/18/2023]
Abstract
Fluorescence lifetime imaging has demonstrated promise as a quantitative measure of cell health. Adaptive optics two-photon excited fluorescence (TPEF) ophthalmoscopy enables excitation of intrinsic retinal fluorophores involved in cellular metabolism and the visual cycle, providing in vivo visualization of retinal structure and function at the cellular scale. Combining these technologies revealed that macaque cones had a significantly longer mean TPEF lifetime than rods at 730 nm excitation. At 900 nm excitation, macaque photoreceptors had a significantly longer mean TPEF lifetime than the retinal pigment epithelium layer. AOFLIO can measure the fluorescence lifetime of intrinsic retinal fluorophores on a cellular scale, revealing differences in lifetime between retinal cell classes.
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Affiliation(s)
- Sarah Walters
- The Institute of Optics, University of Rochester, Rochester, NY 14642, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
- Currently with IDEX Health & Science, West Henrietta, NY 14586, USA
- These authors contributed equally
| | - James A. Feeks
- The Institute of Optics, University of Rochester, Rochester, NY 14642, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
- Currently with IDEX Health & Science, West Henrietta, NY 14586, USA
- These authors contributed equally
| | - Khang T. Huynh
- Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Jennifer J. Hunter
- The Institute of Optics, University of Rochester, Rochester, NY 14642, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14642, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
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8
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Podlipec R, Mur J, Petelin J, Štrancar J, Petkovšek R. Method for controlled tissue theranostics using a single tunable laser source. BIOMEDICAL OPTICS EXPRESS 2021; 12:5881-5893. [PMID: 34692222 PMCID: PMC8515989 DOI: 10.1364/boe.428467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/07/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Tissue diseases and related disorders need to be first recognized using diagnostic methods and then later treated by therapeutic methods-a joint procedure called theranostics. One of the main challenges in the field of retinal therapies remains in the success of the treatment, typically improving the local metabolism, by sparing the surrounding tissue and with the immediate information of the laser effect. In our study, we present a concept for real-time controlled tissue theranostics on a proof-of-concept study capable of using a single tunable ps laser source (in terms of irradiance, fluence, and repetition rate), done on ex-vivo human retinal pigment epithelium. We have found autofluorescence intensity and lifetime imaging diagnostics very promising for the recognition and quantification of laser effects ranging from selective non-destructive molecular tissue modification to complete tissue ablation. The main novelty of our work presents the developed algorithm for optimized theranostics based on the model function used to quantify laser-induced tissue changes through the diagnostics descriptors, fluorescence lifetime and fluorescence intensity parameters. This approach, together with the operation of the single adaptable laser source, can serve as a new theranostics method in personalized medicine in the future not only limited to treat retinal diseases.
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Affiliation(s)
- Rok Podlipec
- Laboratory of Biophysics, Condensed Matter Physics Department, Jožef Stefan Institute, Jamova cesta 39, Ljubljana, Slovenia
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Ion Beam Center, Bautzner Landstraße 400, Dresden 01328, Germany
| | - Jaka Mur
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana, Slovenia
| | - Jaka Petelin
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana, Slovenia
| | - Janez Štrancar
- Laboratory of Biophysics, Condensed Matter Physics Department, Jožef Stefan Institute, Jamova cesta 39, Ljubljana, Slovenia
| | - Rok Petkovšek
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana, Slovenia
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9
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Sorrells JE, Iyer RR, Yang L, Bower AJ, Spillman DR, Chaney EJ, Tu H, Boppart SA. Real-time pixelwise phasor analysis for video-rate two-photon fluorescence lifetime imaging microscopy. BIOMEDICAL OPTICS EXPRESS 2021; 12:4003-4019. [PMID: 34457395 PMCID: PMC8367245 DOI: 10.1364/boe.424533] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 05/06/2023]
Abstract
Two-photon fluorescence lifetime imaging microscopy (FLIM) is a widely used technique in biomedical optical imaging. Presently, many two-photon time-domain FLIM setups are limited by long acquisition and postprocessing times that decrease data throughput and inhibit the ability to image fast sub-second processes. Here, we present a versatile two-photon FLIM setup capable of video-rate (up to 25 fps) imaging with graphics processing unit (GPU)-accelerated pixelwise phasor analysis displayed and saved simultaneously with acquisition. The system uses an analog output photomultiplier tube in conjunction with 12-bit digitization at 3.2 GHz to overcome the limited maximum acceptable photon rate associated with the photon counting electronics in many FLIM systems. This allows for higher throughput FLIM acquisition and analysis, and additionally enables the user to assess sample fluorescence lifetime in real-time. We further explore the capabilities of the system to examine the kinetics of Rhodamine B uptake by human breast cancer cells and characterize the effect of pixel dwell time on the reduced nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) autofluorescence lifetime estimation accuracy.
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Affiliation(s)
- Janet E. Sorrells
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rishyashring R. Iyer
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Lingxiao Yang
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Andrew J. Bower
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Darold R. Spillman
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Eric J. Chaney
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Haohua Tu
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Cancer Center at Illinois, Urbana, IL 61801, USA
- Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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10
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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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11
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Wynne N, Carroll J, Duncan JL. Promises and pitfalls of evaluating photoreceptor-based retinal disease with adaptive optics scanning light ophthalmoscopy (AOSLO). Prog Retin Eye Res 2020; 83:100920. [PMID: 33161127 DOI: 10.1016/j.preteyeres.2020.100920] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows visualization of the living human retina with exquisite single-cell resolution. This technology has improved our understanding of normal retinal structure and revealed pathophysiological details of a number of retinal diseases. Despite the remarkable capabilities of AOSLO, it has not seen the widespread commercial adoption and mainstream clinical success of other modalities developed in a similar time frame. Nevertheless, continued advancements in AOSLO hardware and software have expanded use to a broader range of patients. Current devices enable imaging of a number of different retinal cell types, with recent improvements in stimulus and detection schemes enabling monitoring of retinal function, microscopic structural changes, and even subcellular activity. This has positioned AOSLO for use in clinical trials, primarily as exploratory outcome measures or biomarkers that can be used to monitor disease progression or therapeutic response. AOSLO metrics could facilitate patient selection for such trials, to refine inclusion criteria or to guide the choice of therapy, depending on the presence, absence, or functional viability of specific cell types. Here we explore the potential of AOSLO retinal imaging by reviewing clinical applications as well as some of the pitfalls and barriers to more widespread clinical adoption.
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Affiliation(s)
- Niamh Wynne
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA, USA.
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12
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Lee EJ, Kee HJ, Han JC, Kee C. Evidence-based understanding of disc hemorrhage in glaucoma. Surv Ophthalmol 2020; 66:412-422. [PMID: 32949554 DOI: 10.1016/j.survophthal.2020.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 09/04/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022]
Abstract
Disc hemorrhage is a characteristic finding that is highly associated with glaucoma development or progression. Consequently, the literature commonly designates disc hemorrhage as a "risk factor" for glaucoma progression; however, the exact cause-and-effect relationship or mechanism remains unclear. In this review, we discuss the emerging evidence that disc hemorrhage is a secondary development that follows glaucomatous damage. As our understanding of disc hemorrhage has progressed in recent decades, we suggest the terminology be changed from "risk factor" to "indicator" of ongoing glaucomatous development or progression for a more accurate description, better indication of the clinical implications and, ultimately, a better guide for future research.
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Affiliation(s)
- Eun Jung Lee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyun Joo Kee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jong Chul Han
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Changwon Kee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
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13
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Abstract
High-resolution imaging techniques capable of detecting identifiable endogenous fluorophores in the eye along with genetic testing will dramatically improve diagnostic capabilities in the ophthalmology clinic and accelerate the development of new treatments for blinding diseases. Two-photon excitation (TPE)-based imaging overcomes the filtering of ultraviolet light by the lens of the human eye and thus can be utilized to discover defects in vitamin A metabolism during the regeneration of the visual pigments required for the detection of light. Combining TPE with fluorescence lifetime imaging (FLIM) and spectral analyses offers the potential of detecting diseases of the retina at earlier stages before irreversible structural damage has occurred. The main barriers to realizing the benefits of TPE for imaging the human retina arise from concerns about the high light exposure typically needed for informative TPE imaging and the requirement to correlate the ensuing data with different states of health and disease. To overcome these hurdles, we improved TPE efficiency by controlling temporal properties of the excitation light and employed phasor analyses to FLIM and spectral data in mouse models of retinal diseases. Modeling of retinal photodamage revealed that plasma-mediated effects do not play a role and that melanin-related thermal effects are mitigated by reducing pulse repetition frequency. By using noninvasive TPE imaging we identified molecular components of individual granules in the retinal pigment epithelium and present their analytical characteristics.
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14
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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: 19] [Impact Index Per Article: 4.8] [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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15
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Advances in adaptive optics-based two-photon fluorescence microscopy for brain imaging. Lasers Med Sci 2019; 35:317-328. [PMID: 31729608 DOI: 10.1007/s10103-019-02908-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 10/18/2019] [Indexed: 12/20/2022]
Abstract
Deep tissue imaging using two-photon fluorescence (TPF) techniques have revolutionized the optical imaging community by providing in depth molecular information at the single-cell level. These techniques provide structural and functional aspects of mammalian brain at unprecedented depth and resolution. However, wavefront distortions introduced by the optical system as well as the biological sample (tissue) limit the achievable fluorescence signal-to-noise ratio and resolution with penetration depth. In this review, we discuss on the advances in TPF microscopy techniques for in vivo functional imaging and offer guidelines as to which technologies are best suited for different imaging applications with special reference to adaptive optics.
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16
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Jiang X, Kuchenbecker JA, Touch P, Sabesan R. Measuring and compensating for ocular longitudinal chromatic aberration. OPTICA 2019; 6:981-990. [PMID: 33614858 PMCID: PMC7894623 DOI: 10.1364/optica.6.000981] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/15/2019] [Indexed: 05/18/2023]
Abstract
It is well known that the eye's optics and media introduce monochromatic and chromatic aberration unique to each individual. Once monochromatic aberrations are removed with adaptive optics (AO), longitudinal chromatic aberrations (LCA) define the fidelity for multi-wavelength, high-resolution vision testing and retinal imaging. AO vision simulation systems and AO scanning laser ophthalmoscopes (AOSLOs) typically use the average population LCA to compensate for focus offsets between different wavelengths precluding fine, individualized control. The eye's LCA has been characterized extensively using either subjective (visual perception) or objective (imaging) methods. Classically, these have faced inconsistencies due to extraneous factors related to depth of focus, monochromatic aberration, and wavelength-dependent light interactions with retinal tissue. Here, we introduce a filter-based Badal LCA compensator that offers the flexibility to tune LCA for each individual eye and demonstrate its feasibility for vision testing and imaging using multiple wavelengths simultaneously. Incorporating the LCA compensator in an AOSLO allowed the first objective measurements of LCA based on confocal, multi-wavelength foveal cone images and its comparison to measures obtained subjectively. The objective LCA thus obtained was consistent with subjective estimates in the same individuals and hence resolves the prior discrepancies between them. Overall, the described approach will benefit applications in retinal imaging and vision testing where the focus of multiple wavelengths needs to be controlled independently and simultaneously.
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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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Miura Y. Two-Photon Microscopy (TPM) and Fluorescence Lifetime Imaging Microscopy (FLIM) of Retinal Pigment Epithelium (RPE) of Mice In Vivo. Methods Mol Biol 2019; 1753:73-88. [PMID: 29564782 DOI: 10.1007/978-1-4939-7720-8_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Retinal pigment epithelium (RPE), a monolayer of epithelial cells located between the neural retina and the choroid, plays a significant role in the maintenance of retinal function. Its in vivo imaging is still technically challenging in human eye. With the mouse eye, there is a possibility to look into the RPE through the sclera using two-photon microscopy (TPM). TPM is a two photon-excited nonlinear fluorescence microscopy that enables the observation of deep tissues up to several hundred micrometers. Since the simultaneous absorption of two photons occurs only at the focal plane, spatial resolution of the TPM is quite high, such that pinhole as used in a confocal microscope is not necessary. TPM enables observation of autofluorescence at the cellular level, and thus may provide new insights into the fluorescent molecules in/around RPE cells.The combination of TPM with fluorescence lifetime imaging microscopy (FLIM) may expand the breadth of information about cells and tissues. Fluorescence lifetime is a fluorophore-specific property, which is independent of fluorescence intensity and changes with the alteration of molecular environment. FLIM may have therefore the potentials to distinguish different fluorophores and to indicate the change in the environment of a fluorophore. Some energy metabolisms-related intracellular fluorophores, such as NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), show characteristic fluorescence lifetimes that shift under different molecular environments, and thus their fluorescence lifetime have been used to indicate cell energy metabolic states. These nonlabeling imaging methods offer us the opportunity to engage in the study of the RPE in vivo as well as in vitro both in morphological as well as metabolic aspects.
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Affiliation(s)
- Yoko Miura
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany. .,Department of Ophthalmology, University of Lübeck, Lübeck, Germany.
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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: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/18/2022]
Abstract
Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.
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Affiliation(s)
- Stephen A Burns
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States.
| | - Ann E Elsner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kaitlyn A Sapoznik
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Raymond L Warner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Thomas J Gast
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
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21
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Steven S, Sulai YN, Cheong SK, Bentley J, Dubra A. Long eye relief fundus camera and fixation target with partial correction of ocular longitudinal chromatic aberration. BIOMEDICAL OPTICS EXPRESS 2018; 9:6017-6037. [PMID: 31065410 PMCID: PMC6491002 DOI: 10.1364/boe.9.006017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 05/14/2023]
Abstract
A combined 32° full field of view refractive fundus camera and fixation target with a -20 to +10 diopter sphere correction range is described and demonstrated. The optical setup partially corrects the average longitudinal chromatic aberration and spherical aberration of the human eye, while providing a long eye relief to allow integration with reflective adaptive optics ophthalmoscopes, as a viewfinder. The fundus camera operates with 940 nm light, using a maximum 2.9 mm diameter imaging pupil at the eye. The fixation target uses a light projector capable of delivering red, green and/or blue spatially and temporally modulated stimuli to the retina. The design and performance of each sub-system are discussed, and retinal imaging at various wavelengths is demonstrated.
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Affiliation(s)
- Samuel Steven
- Institute of Optics, University of Rochester, Rochester, NY 14620, USA
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
| | - Yusufu N. Sulai
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Currently at Facebook Reality Labs Redmond, WA 98052, USA
| | - Soon K. Cheong
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
| | - Julie Bentley
- Institute of Optics, University of Rochester, Rochester, NY 14620, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
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22
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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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23
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Wei L, Zhang J, Mai Z, Yang F, Du M, Lin F, Qu J, Chen T. Quantitative dual-channel FRET microscopy. OPTICS EXPRESS 2017; 25:26089-26102. [PMID: 29041270 DOI: 10.1364/oe.25.026089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 10/10/2017] [Indexed: 06/07/2023]
Abstract
Acceptor-sensitized quantitative Förster resonance energy transfer (FRET) measurement (E-FRET) is mainly impeded by donor emission crosstalk and acceptor direct excitation crosstalk. In this paper, we develop a novel E-FRET approach (Lux-E-FRET) based on linear unmixing (Lux) of the fluorescence intensity ratio between two detection channels with each excitation of two different wavelengths. The two detection channels need not to selectively collect the emission of donor or acceptor, and the excitation wavelengths need not to selectively excite donor or acceptor. For a tandem FRET sensor, Lux-E-FRET only needs single excitation wavelength. We performed Lux-E-FRET measurements on our dual-channel wide-field fluorescence microscope for FRET constructs in living cells, and obtained consistent FRET efficiencies with those measured by other methods. Collectively, Lux-E-FRET completely overcomes all spectral crosstalks and thus is applicable to the donor-acceptor pair with larger spectral overlapping.
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