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Oertel J, Fischer D, Tarhan M, Meller D, Hammer M. Fundus autofluorescence lifetimes in age-related macular degeneration versus healthy controls in a pseudophakic population. Acta Ophthalmol 2025. [PMID: 40365784 DOI: 10.1111/aos.17519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2025] [Accepted: 04/28/2025] [Indexed: 05/15/2025]
Abstract
PURPOSE To check whether prolonged fundus autofluorescence (FAF) lifetimes in age-related macular degeneration (AMD) could be an artefact resulting from lens fluorescence. METHODS Fluorescence lifetime imaging ophthalmoscopy (FLIO) was performed in pseudophakic intermediate AMD as well as healthy controls. The median values of FAF lifetimes in the centre, the inner and the outer ring of the ETDRS grid, obtained as amplitude-weighted mean of the lifetimes from a three-exponential fit of the fluorescence decay over time in two spectral channels, as well as peak emission wavelengths (PEW) were compared between patients and controls. The age dependence of FAF lifetime was checked per group. In the patient cohort, FAF lifetimes of individuals with and without subretinal drusenoid deposits (SDD) were compared. RESULTS Forty-four AMD patients (mean age 80.0 ± 6.0 years) and 26 controls (mean age 73.0 ± 10.2 years) were included. The FAF lifetimes of a subgroup of patients (N = 25, mean age 76.3 ± 5.6 years), age-matched to the controls, were significantly longer than those of the controls (all grid areas and spectral channels p < 0.001). FAF lifetimes increased with age in the controls (p = 0.006-0.03), but not in the patients. Patients with SDD had longer FAF lifetimes than those without (p = 0.003-0.068). PEW neither showed significant group differences nor age dependence. CONCLUSIONS Although long fluorescence lifetimes of the lens can affect FAF lifetime measurements, prolonged FAF lifetimes in AMD are specific to the disease and not a lens artefact as shown in pseudophakic eyes. The effect of AMD on the lifetimes outweighs that of age. Patients with SDD, who have a higher risk of AMD progression, also show longer FAF lifetimes.
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Affiliation(s)
- Jana Oertel
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Dominik Fischer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Melih Tarhan
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
- Center for Medical Optics and Photonics, University of Jena, Jena, Germany
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Goerdt L, Clark ME, Thomas TN, Gao L, McGwin G, Hammer M, Crosson JN, Sloan KR, Owsley C, Curcio CA. Fluorescence Lifetime Imaging Ophthalmoscopy, Vision, and Chorioretinal Asymmetries in Aging and Age-Related Macular Degeneration: ALSTAR2. Invest Ophthalmol Vis Sci 2025; 66:56. [PMID: 40257785 PMCID: PMC12020951 DOI: 10.1167/iovs.66.4.56] [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: 01/24/2025] [Accepted: 03/26/2025] [Indexed: 04/22/2025] Open
Abstract
Purpose Eyes with age-related macular degeneration (AMD) and some healthy aged eyes exhibit risk-indicating delays in rod-mediated dark adaptation (RMDA) and prolonged long spectral channel (LSC) lifetimes by fluorescence lifetime imaging ophthalmoscopy (FLIO) in the Early Treatment Diabetic Retinopathy Study (ETDRS) outer ring, especially nasally. To learn FLIO's potential for AMD detection, we correlate FLIO to RMDA. Methods The ALSTAR2 follow-up cohort underwent FLIO, color fundus photography, two-wavelength autofluorescence (for macular pigment optical density [MPOD]), visual function testing, including RMDA (rod intercept time [RIT]). AMD was staged by the Age-Related Eye Disease Study (AREDS) 9-step at baseline and follow-up. In pseudophakic eyes with high-quality FLIO, mean intensity maps and meridian plots were created. Vision data were analyzed using linear regression and Spearman's r. Results Of 155 eyes (155 participants [75 ± 5.0 years; 60.7% female participants]), 67 eyes were healthy, 38 had early (e)AMD, and 50 had intermediate (i)AMD (P = 0.02). LSC lifetimes were longest in iAMD in all ETDRS regions (P < 0.01) and short spectral channel (SSC) lifetimes in inner and outer rings (P < 0.01). The LSC pattern manifested in 65 of 88 AMD eyes and 30 of 67 healthy eyes. Lifetimes were longest on the nasal meridian and shortest on temporal. LSC lifetimes in the inner and outer rings correlated strongly with RIT (r = 0.68). A stable subgroup had short LSC lifetimes and short RIT. SSC correlated weakly with MPOD. Conclusions Prolonged lifetimes in AMD exhibit spatial asymmetry, suggesting mechanisms beyond retinal cells and including choroid. Lifetimes correlate with delayed RMDA, potentially indicating risk for AMD onset and early progression. Further research into SSC signal sources is warranted.
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Affiliation(s)
- Lukas Goerdt
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Mark E. Clark
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Tracy N. Thomas
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Liyan Gao
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Gerald McGwin
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Martin Hammer
- Department of Ophthalmology, University of Jena, Jena, Germany
| | - Jason N. Crosson
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Retina Consultants of Alabama, Birmingham, Alabama, United States
| | - Kenneth R. Sloan
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Cynthia Owsley
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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Lu Y, Jabbari P, Mukhamedshin A, Zvyagin AV. Fluorescence lifetime imaging in drug delivery research. Adv Drug Deliv Rev 2025; 218:115521. [PMID: 39848547 DOI: 10.1016/j.addr.2025.115521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2024] [Revised: 01/10/2025] [Accepted: 01/19/2025] [Indexed: 01/25/2025]
Abstract
Once an exotic add-on to fluorescence microscopy for life science research, fluorescence lifetime imaging (FLIm) has become a powerful and increasingly utilised technique owing to its self-calibration nature, which affords superior quantification over conventional steady-state fluorescence imaging. This review focuses on the state-of-the-art implementation of FLIm related to the formulation, release, dosage, and mechanism of action of drugs aimed for innovative diagnostics and therapy. Quantitative measurements using FLIm have appeared instrumental for encapsulated drug delivery design, pharmacokinetics and pharmacodynamics, pathological investigations, early disease diagnosis, and evaluation of therapeutic efficacy. Attention is paid to the latest advances in lifetime-engineered nanomaterials and practical instrumentation, which begin to show preclinical and clinical translation potential beyond in vitro samples of cells and tissues. Finally, major challenges that need to be overcome in order to facilitate future perspectives are discussed.
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Affiliation(s)
- Yiqing Lu
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia.
| | - Parinaz Jabbari
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia
| | - Anton Mukhamedshin
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USA; Research Center for Translational Medicine, Sirius University of Science and Technology, 354340, Sochi, Russia; National Research Ogarev Mordovia State University, Saransk, Mordovia Republic 430005, Russia
| | - Andrei V Zvyagin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997, Moscow, Russia; School of Mathematical and Physical Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia; Research Center for Translational Medicine, Sirius University of Science and Technology, 354340, Sochi, Russia; National Research Ogarev Mordovia State University, Saransk, Mordovia Republic 430005, Russia
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4
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Tarhan M, Meller D, Hammer M. Hyperautofluorescent material inside areas of macular atrophy may reveal non-lipofuscin fluorophores in late stage AMD. Acta Ophthalmol 2025; 103:e66-e75. [PMID: 39177106 PMCID: PMC11704839 DOI: 10.1111/aos.16752] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 08/08/2024] [Indexed: 08/24/2024]
Abstract
PURPOSE To characterize fundus autofluorescence (FAF) in complete (cRORA) and incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) by fluorescence lifetime imaging ophthalmology (FLIO). METHODS Overall, 98 macular atrophy (MA) lesions in 42 eyes of 37 age-related macular degeneration (AMD) patients (mean age: 80.9 ± 5.8 years), 25 of them classified as iRORA and 73 as cRORA by OCT, were investigated by FLIO in a short (SSC: 498-560 nm) and a long wavelength channel (LSC: 560-720 nm). Differences of FAF lifetimes and peak emission wavelength (PEW) between atrophic lesions and intact retinal pigment epithelium (RPE) in the outer ring of the ETDRS grid were considered. RESULTS FAF lifetimes in MA were longer and PEW were significantly (p < 0.001) shorter than in intact RPE by 112 ± 78 ps (SSC), 91 ± 64 ps (LSC), 27 ± 18 nm (PEW) in iRORA and by 227 ± 112 ps (SSC), 167 ± 81 ps (LSC), and 54 ± 17 nm (PEW) in cRORA. 37% of iRORA and 24% of cRORA were hyperautofluorescent in SSC. Persistent sub-RPE-BL material in MA was newly found as a hyperautofluorescent entity with lifetimes considerably longer than that of drusen and RPE. CONCLUSIONS Despite RPE and, thus, lipofuscin are greatly absent in MA, considerable FAF, preferably at short wavelengths, was found in those lesions. Drusen, persistent sub-RPE-BL material, basal laminar deposits, persistent activated RPE, and sclera were identified as putative sources of this fluorescence. FLIO can help to characterize respective fluorophores.
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Affiliation(s)
- Melih Tarhan
- Department of OphthalmologyUniversity Hospital JenaJenaGermany
| | - Daniel Meller
- Department of OphthalmologyUniversity Hospital JenaJenaGermany
| | - Martin Hammer
- Department of OphthalmologyUniversity Hospital JenaJenaGermany
- Department of OphthalmologyUniversity Hospital BonnBonnGermany
- Center for Medical Optics and PhotonicsUniversity of JenaJenaGermany
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Parameswarappa DC, Kulkarni A, Sahoo NK, Padhy SK, Singh SR, Héon E, Chhablani J. From Cellular to Metabolic: Advances in Imaging of Inherited Retinal Diseases. Diagnostics (Basel) 2024; 15:28. [PMID: 39795556 PMCID: PMC11720060 DOI: 10.3390/diagnostics15010028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2024] [Revised: 12/19/2024] [Accepted: 12/24/2024] [Indexed: 01/13/2025] Open
Abstract
Background: Inherited retinal diseases (IRDs) are a genetically complex group of disorders, usually resulting in progressive vision loss due to retinal degeneration. Traditional imaging methods help in structural assessments, but limitations exist in early functional cellular-level detection that are crucial for guiding new therapies. Methods: This review includes a systematic search of PubMed and Google Scholar for studies on advanced imaging techniques for IRDs. Results: Key modalities covered are adaptive optics, fluorescence lifetime imaging ophthalmoscopy, polarization-sensitive optical coherence tomography, optoretinography, mitochondrial imaging, flavoprotein fluorescence imaging, and retinal oximetry. Each imaging method covers its principles, acquisition techniques, data from healthy eyes, applications in IRDs with specific examples, and current challenges and future directions. Conclusions: Emerging technologies, including adaptive optics and metabolic imaging, offer promising potential for cellular-level imaging and functional correlation in IRDs, allowing for earlier intervention and improved therapeutic targeting. Their integration into clinical practice may significantly improve IRD management and patient outcomes.
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Affiliation(s)
- Deepika C. Parameswarappa
- Ophthalmology and Vision Sciences, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1E8, Canada
| | - Ashwini Kulkarni
- Anant Bajaj Retina Institute, LV Prasad Eye Institute, Vijayawada 521134, India
| | - Niroj Kumar Sahoo
- Anant Bajaj Retina Institute, LV Prasad Eye Institute, Vijayawada 521134, India
| | - Srikanta Kumar Padhy
- Anant Bajaj Retina Institute, LV Prasad Eye Institute, Bhubaneswar 751024, India
| | | | - Elise Héon
- Ophthalmology and Vision Sciences, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1E8, Canada
- Genetics and Genome Biology, SickKids Research Institute, Toronto, ON M5G 1E8, Canada
| | - Jay Chhablani
- UPMC Eye Centre and Choroidal Analysis and Research (CAR) Lab, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Tan KKD, Tsuchida MA, Chacko JV, Gahm NA, Eliceiri KW. Real-time open-source FLIM analysis. FRONTIERS IN BIOINFORMATICS 2023; 3:1286983. [PMID: 38098814 PMCID: PMC10720713 DOI: 10.3389/fbinf.2023.1286983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/08/2023] [Indexed: 12/17/2023] Open
Abstract
Fluorescence lifetime imaging microscopy (FLIM) provides valuable quantitative insights into fluorophores' chemical microenvironment. Due to long computation times and the lack of accessible, open-source real-time analysis toolkits, traditional analysis of FLIM data, particularly with the widely used time-correlated single-photon counting (TCSPC) approach, typically occurs after acquisition. As a result, uncertainties about the quality of FLIM data persist even after collection, frequently necessitating the extension of imaging sessions. Unfortunately, prolonged sessions not only risk missing important biological events but also cause photobleaching and photodamage. We present the first open-source program designed for real-time FLIM analysis during specimen scanning to address these challenges. Our approach combines acquisition with real-time computational and visualization capabilities, allowing us to assess FLIM data quality on the fly. Our open-source real-time FLIM viewer, integrated as a Napari plugin, displays phasor analysis and rapid lifetime determination (RLD) results computed from real-time data transmitted by acquisition software such as the open-source Micro-Manager-based OpenScan package. Our method facilitates early identification of FLIM signatures and data quality assessment by providing preliminary analysis during acquisition. This not only speeds up the imaging process, but it is especially useful when imaging sensitive live biological samples.
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Affiliation(s)
- Kevin K. D. Tan
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI, United States
| | - Mark A. Tsuchida
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI, United States
| | - Jenu V. Chacko
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI, United States
| | - Niklas A. Gahm
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI, United States
- Morgridge Institute for Research, Madison, WI, United States
| | - Kevin W. Eliceiri
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, United States
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI, United States
- Morgridge Institute for Research, Madison, WI, United States
- Department of Medical Physics, University of Wisconsin, Madison, WI, United States
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Sauer L, Vitale AS, Jacoby RS, Hart B, Bernstein PS. FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY IN PATIENTS WITH MACULAR TELANGIECTASIA TYPE 2 WITH AND WITHOUT DIABETES. Retina 2023; 43:1597-1607. [PMID: 37263186 PMCID: PMC10524946 DOI: 10.1097/iae.0000000000003851] [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] [Indexed: 06/03/2023]
Abstract
PURPOSE Macular telangiectasia type 2 (MacTel) is a vision-altering retinal disease with a high prevalence of diabetes. Differences between patients with MacTel with and without diabetes were investigated using fluorescence lifetime imaging ophthalmoscopy (FLIO). METHODS Eighty-six patients with MacTel (59 ± 12 years) were included. 40 patients (46%) did not have diabetes, 16 patients (19%) were prediabetic, and 30 patients (35%) were diabetic. Of these, seven had diabetic retinopathy. 18 diabetic patients without MacTel and 42 age-matched healthy controls were included. FLIO lifetimes (FLTs) were obtained in short (SSC, 498-560 nm) and long (LSC, 560-720 nm) spectral channels from different areas of interest using a Heidelberg Engineering FLIO. RESULTS Fundus autofluorescece lifetimes did not show significant differences when comparing diabetic with nondiabetic MacTel eyes (MacTel zone, SSC, diabetic: 243 ± 65 ps; nondiabetic: 232 ± 51 ps; P = 1.0; LSC, diabetic: 327 ± 66 ps; nondiabetic: 309 ± 54 ps; P = 0.582). Longitudinal changes were similarly unrelated to diabetes status. A nonsignificant trend of increased FLT progression with higher body mass index was found. Fundus autofluorescece lifetimes in diabetic patients without MacTel were significantly shorter within the MacTel zone and longer in the periphery compared with diabetic patients with MacTel. CONCLUSION Although MacTel has a high prevalence of diabetes, FLTs from the MacTel zone are unrelated to diabetes. Fluorescence lifetime imaging ophthalmoscopy retains diagnostic abilities in patients with MacTel even in the presence of prediabetes, diabetes, and advanced diabetic retinopathy. The lack of diabetic FLT changes in the periphery of diabetic patients with MacTel is an interesting finding that needs further investigation.
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Affiliation(s)
- Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah
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Schwanengel LS, Weber S, Simon R, Lehmann T, Augsten R, Meller D, Hammer M. Changes in drusen-associated autofluorescence over time observed by fluorescence lifetime imaging ophthalmoscopy in age-related macular degeneration. Acta Ophthalmol 2023; 101:e154-e166. [PMID: 36017579 DOI: 10.1111/aos.15238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/26/2022] [Accepted: 08/14/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE To observe fundus autofluorescence (FAF) lifetimes and peak emission wavelength (PEW) of drusen with respect to the pathology of the overlying RPE in the follow-up of AMD-patients. METHODS Forty eyes of 38 patients (age: 75.1 ± 7.1 years) with intermediate AMD were included. FAF lifetimes and PEW were recorded by fluorescence lifetime imaging ophthalmoscopy (FLIO). Twenty-six eyes had a follow-up investigation between months 12 and 36, and 10 at months 37-72. AMD progression was retrieved from color fundus photography (CFP) and OCT. Drusen were classified with respect to changes in the overlying RPE into groups no, questionable or faint, and apparent hyperpigmentation based on CFP. RESULTS Among the 210 hyperautofluorescent drusen found at baseline, those with hyperpigmentation had longer lifetimes and shorter PEW than those without. Drusen without hyperpigmentation had shorter lifetimes and PEW than neighboring RPE (all p < 0.001) at baseline, but drusen lifetimes increased, and PEW shortened further over follow-up. Eyes, showing AMD progression, had significantly longer FAF lifetimes at baseline than non-progressing eyes: 282 ± 102 ps versus 245 ± 98 ps, p < 0.001 and 365 ± 44 ps vs. 336 ± 48 ps, p = 0.025 for short and long wavelength FLIO channel, respectively. CONCLUSIONS Depending on hyperpigmentation properties, drusen show lifetimes and PEW different from that of adjacent RPE which change over the natural history of AMD. This difference and change, however, might reflect progressive dysmorphia of the RPE rather than representing fluorescence of drusen material itself. Nevertheless, the observed FAF changes could make FLIO a useful tool for the early detection of AMD progression risk.
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Affiliation(s)
| | - Sebastian Weber
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Rowena Simon
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Thomas Lehmann
- Institute for Medical Statistics, Informatics, und Data Sciences, University Hospital Jena, Jena, Germany
| | - Regine Augsten
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany.,Center for Medical Optics and Photonics, University of Jena, Jena, Germany
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Weber S, Simon R, Schwanengel LS, Curcio CA, Augsten R, Meller D, Hammer M. Fluorescence Lifetime and Spectral Characteristics of Subretinal Drusenoid Deposits and Their Predictive Value for Progression of Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2022; 63:23. [PMID: 36580310 PMCID: PMC9804024 DOI: 10.1167/iovs.63.13.23] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose To measure fundus autofluorescence (FAF) lifetimes and peak emission wavelengths (PEW) of subretinal drusenoid deposits (SDD) in age-related macular degeneration (AMD) and their development over time. Methods Fluorescence lifetime imaging ophthalmoscopy (FLIO) was performed in 30 eyes with optical coherence tomography (OCT)-confirmed early or intermediate AMD and SDD. Contrasts of mean lifetimes in short- (SSC) and long-wavelength channels (LSC), PEW, and relative fluorescence intensity were determined as differences of the respective measures at individual SDD and their environment. Measurements were made at baseline and at follow-up intervals 1 (13-36 months) and 2 (37-72 months), respectively. Results Of 423 SDD found at baseline, 259, 47, and 117 were hypoautofluorescent, isoautofluorescent, and hyperautofluorescent, respectively. FAF lifetimes of SDD were significantly longer than those of their environment by 14.5 ps (SSC, 95% confidence interval [CI], 13.3-15.7 ps) and 3.9 ps (LSC, 3.1-4.7 ps). PEW was shorter by 1.53 nm (1.07-1.98 nm, all contrasts P < 0.001) with higher contrasts for hyperfluorescent SDD. Over follow-up, SDD tended to hyperautofluorescence (relative intensities increased by 3.4% [95% CI, 2.9%-4.1%; P < 0.001] in follow-up 2). Hyperautofluorescence was associated with disruption of the ellipsoid zone on OCT. Disease progression to late-stage AMD was associated with higher lifetime contrast in SSC (15.9ps [14.2-17.6 ps] vs. 11.7 ps [9.9-13.5 ps], P < 0.001) at baseline. Conclusions SDD show longer FAF lifetimes and shorter PEW than their environments. A high lifetime contrast of SDD in SSC might predict disease progression to late-stage AMD.
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Affiliation(s)
- Sebastian Weber
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Rowena Simon
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | | | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Regine Augsten
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany,Center for Medical Optics and Photonics, Univ. of Jena, Jena, Germany
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10
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Simon R, Jentsch M, Karimimousivandi P, Cao D, Messinger JD, Meller D, Curcio CA, Hammer M. Prolonged Lifetimes of Histologic Autofluorescence in Ectopic Retinal Pigment Epithelium in Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 36469025 PMCID: PMC9730734 DOI: 10.1167/iovs.63.13.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose The purpose of this study was to investigate histologic autofluorescence lifetimes and spectra of retinal pigment epithelium (RPE) on the transition from normal aging to RPE activation and migration in age-related macular degeneration (AMD). Methods Autofluorescence lifetimes and spectra of 9 donor eyes were analyzed in cryosections by means of 2-photon excited fluorescence at 960 nm. Spectra were detected at 483 to 665 nm. Lifetimes were measured using time-correlated single photon counting in 2 spectral channels: 500 to 550 nm (short-wavelength spectral channel [SSC]) and 550 to 700 nm (long-wavelength spectral channel [LSC]). Fluorescence decays over time were approximated by a series of three exponential functions. The amplitude-weighted mean fluorescence lifetime was determined. Markers for retinoid activity (RPE65) and immune function (CD68) were immunolocalized in selected neighboring sections. Results We identified 9 RPE morphology phenotypes resulting in 399 regions of interest (ROIs) for spectral and 497 ROIs for lifetime measurements. RPE dysmorphia results in a shorter wavelength peak of spectral emission: normal aging versus RPE migrated into the retina (intraELM) = 601.7 (9.5) nm versus 581.6 (7.3) nm, P < 0.001, whereas autofluorescence lifetimes increase: normal aging versus intraELM: SSC 180 (44) picosecond (ps) versus 320 (86) ps, P < 0.001; and LSC 250 (55) ps versus 441 (76) ps, P < 0.001. Ectopic RPE within the neurosensory retina is strongly CD68 positive and RPE65 negative. Conclusions In the process of RPE degeneration, comprising different steps of dysmorphia and migration, lengthening of autofluorescence lifetimes and a hypsochromic shift of emission spectra can be observed. These autofluorescence changes might provide early biomarkers for AMD progression and contribute to our understanding of RPE-driven pathology.
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Affiliation(s)
- Rowena Simon
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Marius Jentsch
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | | | - Dongfeng Cao
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Jeffrey D Messinger
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany.,Center for Medical Optics and Photonics, University of Jena, Jena, Germany
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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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12
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Hammer M, Simon R, Meller D, Klemm M. Combining fluorescence lifetime with spectral information in fluorescence lifetime imaging ophthalmoscopy (FLIO). BIOMEDICAL OPTICS EXPRESS 2022; 13:5483-5494. [PMID: 36425633 PMCID: PMC9664887 DOI: 10.1364/boe.457946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 06/01/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) provides information on fluorescence lifetimes in two spectral channels as well as the peak emission wavelength (PEW) of the fluorescence. Here, we combine these measures in an integral three-dimensional lifetime-PEW metric vector and determine a normal range for this vector from measurements in young healthy subjects. While for these control subjects 97 (±8) % (median (interquartile range)) of all para-macular pixels were covered by this normal vector range, it was 67 (±55) % for the elderly healthy, 38 (±43) % for age-related macular degeneration (AMD)-suspect subjects, and only 6 (±4) % for AMD patients. The vectors were significantly different for retinal pigment epithelium (RPE) lesions in AMD patients from that of non-affected tissue (p < 0.001). Lifetime- PEW plots allowed to identify possibly pathologic fundus areas by fluorescence parameters outside a 95% quantile per subject. In a patient follow-up, changes in fluorescence parameters could be traced in the lifetime-PEW metric, showing their change over disease progression.
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Affiliation(s)
- Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
- Center for Medical Optics and Photonics, Univ. of Jena, Jena, Germany
| | - Rowena Simon
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technical Univ. Ilmenau, Ilmenau, Germany
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13
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Hammer M, Jakob-Girbig J, Schwanengel L, Curcio CA, Hasan S, Meller D, Schultz R. Progressive Dysmorphia of Retinal Pigment Epithelium in Age-Related Macular Degeneration Investigated by Fluorescence Lifetime Imaging. Invest Ophthalmol Vis Sci 2021; 62:2. [PMID: 34491262 PMCID: PMC8431975 DOI: 10.1167/iovs.62.12.2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose The purpose of this study was to observe changes of the retinal pigment epithelium (RPE) on the transition from dysmorphia to atrophy in age-related macular degeneration (AMD) by fluorescence lifetime imaging ophthalmoscopy (FLIO). Methods Multimodal imaging including color fundus photography (CFP), optical coherence tomography (OCT), fundus autofluorescence (FAF) imaging, and FLIO was performed in 40 eyes of 37 patients with intermediate AMD and no evidence for geographic atrophy or macular neovascularization (mean age = 74.2 ± 7.0 years). Twenty-three eyes were followed for 28.3 ± 18.3 months. Seven eyes had a second follow-up after 46.6 ± 9.0 months. Thickened RPE on OCT, hyperpigmentation on CFP, hyper-reflective foci (HRF) on OCT, attributed to single or clustered intraretinal RPE, were identified. Fluorescence lifetimes in two spectral channels (short-wavelength spectral channel [SSC] = 500–560 nm, long-wavelength spectral channel [LSC] = 560–720 nm) as well as emission spectrum intensity ratio (ESIR) of the lesions were measured by FLIO. Results As hyperpigmented areas form and RPE migrates into the retina, FAF lifetimes lengthen and ESRI of RPE cells increase. Thickened RPE showed lifetimes of 256 ± 49 ps (SSC) and 336 ± 35 ps (LSC) and an ESIR of 0.552 ± 0.079. For hyperpigmentation, these values were 317 ± 68 ps (p < 0.001), 377 ± 56 ps (P < 0.001), and 0.609 ± 0.081 (P = 0.001), respectively, and for HRF 337 ± 79 ps (P < 0.001), 414 ± 50 ps (P < 0.001), and 0.654 ± 0.075 (P < 0.001). Conclusions In the process of RPE degeneration, comprising different steps of dysmorphia, hyperpigmentation, and migration, lengthening of FAF lifetimes and a hypsochromic shift of emission spectra can be observed by FLIO. Thus, FLIO might provide early biomarkers for AMD progression and contribute to our understanding of RPE pathology.
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Affiliation(s)
- Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany.,Center for Medical Optics and Photonics, Univ. of Jena, Jena, Germany
| | | | - Linda Schwanengel
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Somar Hasan
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Daniel Meller
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Rowena Schultz
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
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14
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Prinke P, Haueisen J, Klee S, Rizqie MQ, Supriyanto E, König K, Breunig HG, Piątek Ł. Automatic segmentation of skin cells in multiphoton data using multi-stage merging. Sci Rep 2021; 11:14534. [PMID: 34267247 PMCID: PMC8282875 DOI: 10.1038/s41598-021-93682-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 06/27/2021] [Indexed: 01/10/2023] Open
Abstract
We propose a novel automatic segmentation algorithm that separates the components of human skin cells from the rest of the tissue in fluorescence data of three-dimensional scans using non-invasive multiphoton tomography. The algorithm encompasses a multi-stage merging on preprocessed superpixel images to ensure independence from a single empirical global threshold. This leads to a high robustness of the segmentation considering the depth-dependent data characteristics, which include variable contrasts and cell sizes. The subsequent classification of cell cytoplasm and nuclei are based on a cell model described by a set of four features. Two novel features, a relationship between outer cell and inner nucleus (OCIN) and a stability index, were derived. The OCIN feature describes the topology of the model, while the stability index indicates segment quality in the multi-stage merging process. These two new features, combined with the local gradient magnitude and compactness, are used for the model-based fuzzy evaluation of the cell segments. We exemplify our approach on an image stack with 200 × 200 × 100 μm3, including the skin layers of the stratum spinosum and the stratum basale of a healthy volunteer. Our image processing pipeline contributes to the fully automated classification of human skin cells in multiphoton data and provides a basis for the detection of skin cancer using non-invasive optical biopsy.
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Affiliation(s)
- Philipp Prinke
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.
| | - Jens Haueisen
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany
| | - Sascha Klee
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,Division Biostatistics and Data Science, Department of General Health Studies, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, 3500, Krems, Austria
| | - Muhammad Qurhanul Rizqie
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,Informatics Engineering Program, Universitas Sriwijaya, Palembang, South Sumatera, Indonesia
| | - Eko Supriyanto
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,IJN-UTM Cardiovascular Engineering Centre, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia
| | - Karsten König
- Department of Biophotonics and Laser Technology, Saarland University, Campus A5.1, 66123, Saarbrücken, Germany.,JenLab GmbH, Johann-Hittorf-Straße 8, 12489, Berlin, Germany
| | - Hans Georg Breunig
- Department of Biophotonics and Laser Technology, Saarland University, Campus A5.1, 66123, Saarbrücken, Germany.,JenLab GmbH, Johann-Hittorf-Straße 8, 12489, Berlin, Germany
| | - Łukasz Piątek
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,Department of Artificial Intelligence, University of Information Technology and Management, H. Sucharskiego 2 Str, 35-225, Rzeszów, Poland
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15
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LONGITUDINAL FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY ANALYSIS IN PATIENTS WITH MACULAR TELANGIECTASIA TYPE 2 (MacTel). Retina 2021; 41:1416-1427. [PMID: 34137386 DOI: 10.1097/iae.0000000000003055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Fluorescence lifetime imaging ophthalmoscopy (FLIO) shows characteristic patterns in macular telangiectasia Type 2 (MacTel). This study investigates FLIO changes over time to better understand disease progression. METHODS Thirty-three patients with MacTel (age 60 ± 15 years) were followed at the Moran Eye Center with a prototype Heidelberg Engineering FLIO. The mean follow-up time was 19 ± 8 months (range 6-34 months). Fundus autofluorescence was excited at 473 nm, and FLIO lifetimes were recorded in in short (498-560 nm) and long (560-720 nm) spectral wavelengths channels. RESULTS Autofluorescence lifetimes imaging ophthalmoscopy lifetimes from the MacTel area prolonged significantly over time (subfield T1, baseline: short spectral channel 210 ± 54 ps, long spectral channel 269 ± 58 ps; follow-up: short spectral channel 225 ± 59 ps, P < 0.001, long spectral channel 282 ± 64 ps, P < 0.01). The average 12-months prolongation of FLIO lifetimes was 9 ps (short spectral channel) and 8 ps (long spectral channel). Autofluorescence lifetimes changes correlated positively with ellipsoid zone loss and negatively with changes in retinal thickness. CONCLUSION Autofluorescence lifetimes in MacTel slowly prolong over time, and temporal patterns progress to full rings. Detailed knowledge about FLIO changes will aid in understanding disease development and progression.
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16
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Lincke JB, Dysli C, Jaggi D, Fink R, Wolf S, Zinkernagel MS. The Influence of Cataract on Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO). Transl Vis Sci Technol 2021; 10:33. [PMID: 34004011 PMCID: PMC8088233 DOI: 10.1167/tvst.10.4.33] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the influence of lens opacifications on fluorescence lifetime imaging ophthalmoscopy (FLIO). Methods Forty-seven eyes of 45 patients were included. Mean fluorescence lifetimes (Tm) were recorded with a fluorescence lifetime imaging ophthalmoscope in a short spectral channel (SSC) and a long spectral channel (LSC). Retinal and lens autofluorescence lifetimes were measured in subjects before and after cataract surgery. Lens opacification was graded using the Lens Opacities Classification System III (LOCS III) classification. Results The retinal Tm decreased significantly after cataract surgery in both spectral channels (SSC: -53%, P < 0.0001; LSC: -26%, P = 0.0041). The lens Tm differed significantly between the crystalline and the artificial lens in both spectral channels (P < 0.0001). The "nuclear opacity" and "nuclear color" score of the LOCS III classification correlated significantly with the mean Tm difference in both spectral channels (P < 0.0001). Conclusions Lens opacification results in significantly longer retinal Tm. Therefore the lens status has to be considered when performing cross-sectional fluorescence lifetime analysis. Cataract-formation and cataract-surgery needs to be considered when conducting longitudinal studies. Grading of nuclear opacity following the LOCS III classification provides an approximate conversion formula for the mean change of lifetimes, which can be helpful in the interpretation of data in patients with lens opacities. Translational Relevance FLIO is significantly influenced by lens opacities. Using a lens opacity grading scheme and measuring fluorescence lifetimes before and after cataract surgery, an approximative conversion formula can be calculated, which enables the comparison of lifetimes after cataract surgery or over the course of time.
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Affiliation(s)
- Joel-Benjamin Lincke
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Chantal Dysli
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Damian Jaggi
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Rahel Fink
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Sebastian Wolf
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Martin S Zinkernagel
- Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland
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17
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Goerdt L, Sauer L, Vitale AS, Modersitzki NK, Fleckenstein M, Bernstein PS. Comparing Fluorescence Lifetime Imaging Ophthalmoscopy in Atrophic Areas of Retinal Diseases. Transl Vis Sci Technol 2021; 10:11. [PMID: 34110387 PMCID: PMC8196421 DOI: 10.1167/tvst.10.7.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a non-invasive imaging modality to investigate the human retina. This study compares FLIO lifetimes in different degenerative retinal diseases. Methods Included were eyes with retinal pigment epithelium (RPE) and/or photoreceptor atrophy due to Stargardt disease (n = 66), pattern dystrophy (n = 18), macular telangiectasia type 2 (n = 49), retinitis pigmentosa (n = 28), choroideremia (n = 26), and geographic atrophy (n = 32) in age-related macular degeneration, as well as 37 eyes of 37 age-matched healthy controls. Subjects received Heidelberg Engineering FLIO, autofluorescence intensity, and optical coherence tomography imaging. Amplitude-weighted mean FLIO lifetimes (τm) were calculated and analyzed. Results Retinal FLIO lifetimes show significant differences depending on the disease. Atrophic areas in geographic atrophy and choroideremia showed longest mean FLIO lifetimes. τm values within areas of RPE and outer nuclear layer atrophy were significantly longer than within areas with preserved outer nuclear layer (P < 0.001) or non-atrophic areas (P < 0.001). Conclusions FLIO is able to contribute additional information regarding differences in chronic degenerative retinal diseases. Although it cannot replace conventional autofluorescence imaging, FLIO adds to the knowledge in these diseases and may help with the correct differentiation between them. This may lead to a more in-depth understanding of the pathomechanisms related to atrophy and types of progression. Translational Relevance Differences between atrophic retinal diseases highlighted by FLIO may indicate separate pathomechanisms leading to atrophy and disease progression.
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Affiliation(s)
- Lukas Goerdt
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA.,Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | | | | | | | - Paul S Bernstein
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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18
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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: 0.8] [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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19
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Vitale AS, Sauer L, Modersitzki NK, Bernstein PS. Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Patients with Choroideremia. Transl Vis Sci Technol 2020; 9:33. [PMID: 33062396 PMCID: PMC7533737 DOI: 10.1167/tvst.9.10.33] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/24/2020] [Indexed: 12/22/2022] Open
Abstract
Purpose To provide a detailed characterization of choroideremia (CHM) using fluorescence lifetime imaging ophthalmoscopy (FLIO) and to provide a deeper understanding of disease-related changes and progression. Methods Twenty-eight eyes of 14 patients with genetically confirmed CHM (mean age, 28 ± 14 years) and 14 age-matched healthy subjects were investigated in this study. FLIO images of a 30° retinal field were collected at the Moran Eye Center using a Heidelberg Engineering FLIO device. FLIO lifetimes were recorded in short spectral channels (SSC; 498-560 nm) and long spectral channels (LSC; 560-720 nm), and mean autofluorescence lifetimes (τm) were calculated. Optical coherence tomography (OCT) scans were recorded for each patient. Three patients were re-imaged after a year. Results Patients with CHM exhibit specific FLIO lifetime patterns. Prolonged FLIO lifetimes (around 600-700 ps) were found in the peripheral macula corresponding to atrophy in OCT imaging. In the central macula, τm was unrelated to autofluorescence intensity. Some areas of persistent retinal pigment epithelial islands had prolonged FLIO lifetimes, whereas other areas of hypofluorescence had short FLIO lifetimes. At 1-year follow-up, FLIO lifetimes were significantly prolonged within atrophic areas (P < 0.05). Conclusions FLIO shows distinct patterns in patients with CHM, indicating lesions of atrophy and areas of preserved function in the presence or absence of findings in fundus autofluorescence intensity images. FLIO may provide differentiated knowledge about pathophysiology and atrophy progression in CHM compared to conventional imaging modalities. Translational Relevance FLIO shows distinctive lifetime patterns that potentially identify areas of function, atrophy, and disease progression in patients with CHM.
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Affiliation(s)
- Alexandra S. Vitale
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Lydia Sauer
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Natalie K. Modersitzki
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Paul S. Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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20
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Sauer L, Vitale AS, Milliken CM, Modersitzki NK, Blount JD, Bernstein PS. Autofluorescence Lifetimes Measured with Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) Are Affected by Age, but Not by Pigmentation or Gender. Transl Vis Sci Technol 2020; 9:2. [PMID: 32879759 PMCID: PMC7442880 DOI: 10.1167/tvst.9.9.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 06/07/2020] [Indexed: 12/25/2022] Open
Abstract
Purpose Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a novel modality to investigate the human retina. This study aims to characterize the effects of age, pigmentation, and gender in FLIO. Methods A total of 97 eyes from 97 healthy subjects (mean age 37 ± 18 years, range 9-85 years) were investigated in this study. This study included 47 (49%) females and 50 males. The pigmentation analysis was a substudy including 64 subjects aged 18 to 40 years (mean age 29 ± 6 years). These were categorized in groups A (darkly pigmented, 8), B (medium pigmented, 20), and C (lightly pigmented, 36). Subjects received Heidelberg Engineering FLIO and optical coherence tomography imaging. Retinal autofluorescence lifetimes were detected in two spectral channels (short spectral channel [SSC]: 498-560 nm; long spectral channel [LSC]: 560-720 nm), and amplitude-weighted mean fluorescence lifetimes (τm) were calculated. Additionally, autofluorescence lifetimes of melanin were measured in a cuvette. Results Age significantly affected FLIO lifetimes, and age-related FLIO changes in the SSC start at approximately age 35 years, whereas the LSC shows a consistent prolongation with age from childhood. There were no gender- or pigmentation-specific significant differences of autofluorescence lifetimes. Conclusions This study confirms age-effects in FLIO but shows that the two channels are affected differently. The LSC appears to show the lifelong accumulation of lipofuscin. Furthermore, it is important to know that neither gender nor pigmentation significantly affect FLIO lifetimes. Translational Relevance This study helps to understand the FLIO technology better, which will aid in conducting future clinical studies.
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Affiliation(s)
- Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | | | - Cole M Milliken
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA.,Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA
| | | | - J David Blount
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Paul S Bernstein
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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21
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Brauer JL, Schultz R, Klemm M, Hammer M. Influence of Lens Fluorescence on Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) Fundus Imaging and Strategies for Its Compensation. Transl Vis Sci Technol 2020; 9:13. [PMID: 32855860 PMCID: PMC7422756 DOI: 10.1167/tvst.9.8.13] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/15/2020] [Indexed: 12/04/2022] Open
Abstract
Purpose To explore the contribution of crystalline lens fluorescence to fluorescence lifetimes measured with fluorescence lifetime imaging ophthalmoscopy (FLIO) and to propose a computational model to reduce the lens influence. Methods FLIO, which detects autofluorescence decay over time in a short-wavelength spectral channel (SSC, 498–560 nm) and a long-wavelength spectral channel (LSC, 560–720 nm), was performed on 32 patients before and after cataract extraction. The mean autofluorescence lifetime (τm) of the fundus was determined from a three-exponential fit of the postoperative fluorescence decays. The preoperative measurements were fit with series of exponential functions in which one fluorescence component was time-shifted in order to represent lens fluorescence. Results Postoperatively, τm was 185 ± 22 ps in the SSC and 209 ± 34 ps in the LSC at the posterior pole. These values were best reproduced by fitting the postoperative measurements with a three-exponential model with a time-shifted third fluorescence component (SSC, 203 ± 45 ps; LSC, 215 ± 29 ps), whereas disregarding time-shifted lens fluorescence resulted in significantly (P < 0.001) longer τm values (SSC, 474 ± 206 ps; LSC, 215 ± 29 ps). The fluorescence of the cataract lens contributed to the total fluorescence by 54.2 ± 10.6% (SSC) and 29.5 ± 9.9% (LSC). Conclusions Cataract lens fluorescence greatly alters fluorescence lifetimes measured at the fundus by FLIO, resulting in an overestimation of the lifetimes; however, this may be compensated for considerably by taking lens influence into account in the fitting model. Translational Relevance This study investigates cataract fluorescence in FLIO and a mathematical model for compensation of this influence.
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Affiliation(s)
| | - Rowena Schultz
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Matthias Klemm
- Technical University Ilmenau, Institute for Biomedical Techniques and Informatics, Ilmenau, Germany
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany.,Center for Medical Optics and Photonics, University of Jena, Jena, Germany
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Barkauskas DS, Medley G, Liang X, Mohammed YH, Thorling CA, Wang H, Roberts MS. Using in vivo multiphoton fluorescence lifetime imaging to unravel disease-specific changes in the liver redox state. Methods Appl Fluoresc 2020; 8:034003. [PMID: 32422610 DOI: 10.1088/2050-6120/ab93de] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Multiphoton fluorescence lifetime microscopy has revolutionized studies of pathophysiological and xenobiotic dynamics, enabling the spatial and temporal quantification of these processes in intact organs in vivo. We have previously used multiphoton fluorescence lifetime microscopy to characterise the morphology and amplitude weighted mean fluorescence lifetime of the endogenous fluorescent metabolic cofactor nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) of mouse livers in vivo following induction of various disease states. Here, we extend the characterisation of liver disease models by using nonlinear regression to estimate the unbound, bound fluorescence lifetimes for NAD(P)H, flavin adenine dinucleotide (FAD), along with metabolic ratios and examine the impact of using multiple segmentation methods. We found that NAD(P)H amplitude ratio, and fluorescence lifetime redox ratio can be used as discriminators of diseased liver from normal liver. The redox ratio provided a sensitive measure of the changes in hepatic fibrosis and biliary fibrosis. Hepatocellular carcinoma was associated with an increase in spatial heterogeneity and redox ratio coupled with a decrease in mean fluorescence lifetime. We conclude that multiphoton fluorescence lifetime microscopy parameters and metabolic ratios provided insights into the in vivo redox state of diseased compared to normal liver that were not apparent from a global, mean fluorescence lifetime measurement alone.
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Affiliation(s)
- Deborah S Barkauskas
- Therapeutics Research Group, University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD 4102, Australia
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Sauer L, Vitale AS, Andersen KM, Hart B, Bernstein PS. FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY (FLIO) PATTERNS IN CLINICALLY UNAFFECTED CHILDREN OF MACULAR TELANGIECTASIA TYPE 2 (MACTEL) PATIENTS. Retina 2020; 40:695-704. [PMID: 31517727 PMCID: PMC7062574 DOI: 10.1097/iae.0000000000002646] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE Macular telangiectasia Type 2 (MacTel) is an inherited retinal disease following an autosomal dominant pattern with late onset and reduced penetrance. Fluorescence lifetime imaging ophthalmoscopy (FLIO) enhances diagnosis by showing distinct changes in MacTel. This study investigates FLIO-associated changes in clinically unaffected family members. METHODS Eighty-one patients with MacTel (61 ± 12 years), 33 clinically healthy children under age 40 years of these MacTel patients (MacTel-C; 31 ± 6 years), 27 other family members (children over age 40 years, siblings, and parents) and 30 controls were investigated with the Heidelberg FLIO. All subjects underwent multimodal conventional imaging, including optical coherence tomography, blue-light reflectance, fluorescein angiography, and macular pigment imaging. RESULTS All 81 patients with MacTel showed typical FLIO patterns. Of the 33 investigated MacTel-C with completely normal eye examinations and conventional imaging, 12 (36%) show FLIO patterns consistent with early MacTel. CONCLUSION Prolonged FLIO lifetimes in the parafoveal area within the short spectral channel, especially temporally, are MacTel-specific. Fluorescence lifetime imaging ophthalmoscopy detects these lifetime patterns in over one-third of clinically unaffected MacTel-C. Although further studies will be necessary to determine the specificity of FLIO, it may help diagnose MacTel before conventional imaging modalities show changes or patients experience visual disturbances. Early detection may facilitate future gene discovery studies and interventional trials.
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Affiliation(s)
- Lydia Sauer
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Alexandra S. Vitale
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Karl M. Andersen
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
- Geisinger Commonwealth School of Medicine, Scranton, PA, USA
| | - Barbara Hart
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Paul S. Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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Sauer L, Komanski CB, Vitale AS, Hansen ED, Bernstein PS. Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Eyes With Pigment Epithelial Detachments Due to Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2019; 60:3054-3063. [PMID: 31348823 PMCID: PMC6660189 DOI: 10.1167/iovs.19-26835] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate fluorescence lifetime imaging ophthalmoscopy (FLIO) in neovascular AMD and pigment epithelial detachments (PEDs). Methods A total of 46 eyes with PEDs (>350 μm) as well as age-matched healthy controls were included in this study. We found 28 eyes showed neovascular AMD (nvAMD), and 17 had nonneovascular (dry) AMD (dAMD). The Heidelberg Engineering FLIO excited fluorescence at 473 nm. Fluorescence decays were detected in two spectral channels (498–560 nm; 560–720 nm) to determine fluorescence lifetimes of endogenous fluorophores in their specific spectral emission ranges. Mean fluorescence lifetimes (τm) were investigated. Multimodal imaging was reviewed by two ophthalmologists who circumscribed and classified PEDs as either serous (n = 4), hemorrhagic (n = 4), fibrovascular (n = 16), drusenoid (n = 17), or mixed (n = 5). Blood samples from a healthy subject and a patient with PED were investigated in a quartz cuvette. Results Eyes with nvAMD show similar FLIO patterns to dAMD: ring-shaped prolongations of τm 3 to 6 mm from the fovea. Different PED-forms show characteristic τm, while serous and hemorrhagic PEDs exhibit shortened τm, drusenoid PEDs show prolonged τm, and τm in fibrovascular PEDs is variable. Areas corresponding to sub-/intraretinal fluid display shortened τm. Ex vivo studies of blood also show short τm. Conclusions The previously described dAMD-related FLIO pattern is also present in nvAMD. Short τm in serous, fibrovascular, and hemorrhagic PEDs as well as sub/intraretinal fluid may disrupt this pattern. FLIO appears to differentiate between PEDs, hemorrhage, and fluid. Additionally, ex vivo studies of human blood help to better interpret FLIO images.
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Affiliation(s)
- Lydia Sauer
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Christopher B Komanski
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Alexandra S Vitale
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Eric D Hansen
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
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Sauer L, Calvo CM, Vitale AS, Henrie N, Milliken CM, Bernstein PS. Imaging of Hydroxychloroquine Toxicity with Fluorescence Lifetime Imaging Ophthalmoscopy. ACTA ACUST UNITED AC 2019; 3:814-825. [DOI: 10.1016/j.oret.2019.04.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/20/2019] [Accepted: 04/23/2019] [Indexed: 12/16/2022]
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Klemm M, Sauer L, Klee S, Link D, Peters S, Hammer M, Schweitzer D, Haueisen J. Bleaching effects and fluorescence lifetime imaging ophthalmoscopy. BIOMEDICAL OPTICS EXPRESS 2019; 10:1446-1461. [PMID: 30891358 PMCID: PMC6420301 DOI: 10.1364/boe.10.001446] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 12/02/2018] [Accepted: 12/02/2018] [Indexed: 05/13/2023]
Abstract
This study investigates the influence of photopigment bleaching on autofluorescence lifetimes in the fundus in 21 young healthy volunteers. Three measurements of 30° retinal fields in two spectral channels (SSC: 498-560 nm, LSC: 560-720 nm) were obtained for each volunteer using fluorescence lifetime imaging ophthalmoscopy (FLIO). After dark-adaptation by wearing a custom-made lightproof mask for 30 minutes, the first FLIO-measurement was recorded (dark-adapted state). Subsequently, the eye was bleached for 1 minute (luminance: 3200 cd/m2), followed by a second FLIO-measurement (bleached state). Following an additional 10 minute dark adaptation using the mask, a final FLIO-measurement was recorded (recovered state). Average values of the fluorescence lifetimes were calculated from within different areas of a standardized early treatment diabetic retinopathy study (ETDRS) grid (central area, inner and outer rings). The acquisition time in the bleached state was significantly shortened by approximately 20%. The SSC did not show any significant changes in fluorescence lifetimes with photopigment bleaching, only the LSC showed small but significant bleaching-related changes in the fluorescence lifetimes τ1 and τ2 from all regions, as well as the mean fluorescence lifetime in the central area. The fluorescence lifetime differences caused by bleaching were by far less significant than pathological changes caused by eye diseases. The magnitudes of fluorescence lifetime changes are <10% and do not interfere with healthy or disease related FLIO patterns. Thus, we conclude that bleaching is not a relevant confounder in current clinical applications of FLIO.
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Affiliation(s)
- Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Lydia Sauer
- University Hospital Jena, Department of Ophthalmology, Am Klinikum 1, 07743 Jena, Germany
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Sascha Klee
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Dietmar Link
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Sven Peters
- University Hospital Jena, Department of Ophthalmology, Am Klinikum 1, 07743 Jena, Germany
| | - Martin Hammer
- University Hospital Jena, Department of Ophthalmology, Am Klinikum 1, 07743 Jena, Germany
- University of Jena, Center for Biomedical Optics and Photonics, 07740 Jena, Germany
| | - Dietrich Schweitzer
- University Hospital Jena, Department of Ophthalmology, Am Klinikum 1, 07743 Jena, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
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Brown CN, Green BD, Thompson RB, den Hollander AI, Lengyel I. Metabolomics and Age-Related Macular Degeneration. Metabolites 2018; 9:metabo9010004. [PMID: 30591665 PMCID: PMC6358913 DOI: 10.3390/metabo9010004] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/11/2022] Open
Abstract
Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.
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Affiliation(s)
- Connor N Brown
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
| | - Brian D Green
- Institute for Global Food Security (IGFS), Queen's University Belfast, Belfast BT9 6AG, UK.
| | - Richard B Thompson
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
| | - Anneke I den Hollander
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen 6525 EX, The Netherlands.
| | - Imre Lengyel
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
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Sauer L, Andersen KM, Dysli C, Zinkernagel MS, Bernstein PS, Hammer M. Review of clinical approaches in fluorescence lifetime imaging ophthalmoscopy. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-20. [PMID: 30182580 PMCID: PMC8357196 DOI: 10.1117/1.jbo.23.9.091415] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 07/24/2018] [Indexed: 05/04/2023]
Abstract
Autofluorescence-based imaging techniques have become very important in the ophthalmological field. Being noninvasive and very sensitive, they are broadly used in clinical routines. Conventional autofluorescence intensity imaging is largely influenced by the strong fluorescence of lipofuscin, a fluorophore that can be found at the level of the retinal pigment epithelium. However, different endogenous retinal fluorophores can be altered in various diseases. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an imaging modality to investigate the autofluorescence of the human fundus in vivo. It expands the level of information, as an addition to investigating the fluorescence intensity, and autofluorescence lifetimes are captured. The Heidelberg Engineering Spectralis-based fluorescence lifetime imaging ophthalmoscope is used to investigate a 30-deg retinal field centered at the fovea. It detects FAF decays in short [498 to 560 nm, short spectral channel (SSC) and long (560 to 720 nm, long spectral channel (LSC)] spectral channels, the mean fluorescence lifetimes (τm) are calculated using bi- or triexponential approaches. These are meant to be relatively independent of the fluorophore's intensity; therefore, fluorophores with less intense fluorescence can be detected. As an example, FLIO detects the fluorescence of macular pigment, retinal carotenoids that help protect the human fundus from light damages. Furthermore, FLIO is able to detect changes related to various retinal diseases, such as age-related macular degeneration, albinism, Alzheimer's disease, diabetic retinopathy, macular telangiectasia type 2, retinitis pigmentosa, and Stargardt disease. Some of these changes can already be found in healthy eyes and may indicate a risk to developing such diseases. Other changes in already affected eyes seem to indicate disease progression. This review article focuses on providing detailed information on the clinical findings of FLIO. This technique detects not only structural changes at very early stages but also metabolic and disease-related alterations. Therefore, it is a very promising tool that might soon be used for early diagnostics.
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Affiliation(s)
- Lydia Sauer
- University Hospital Jena, Jena, Thuringia, Germany
- University of Utah, John A. Moran Eye Center, Salt Lake City, Utah, United States
| | - Karl M. Andersen
- University of Utah, John A. Moran Eye Center, Salt Lake City, Utah, United States
- Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania, United States
| | - Chantal Dysli
- Bern University Hospital, Inselspital, Department of Ophthalmology, Bern, Switzerland
| | - Martin S. Zinkernagel
- Bern University Hospital, Inselspital, Department of Ophthalmology, Bern, Switzerland
| | - Paul S. Bernstein
- University of Utah, John A. Moran Eye Center, Salt Lake City, Utah, United States
| | - Martin Hammer
- University Hospital Jena, Jena, Thuringia, Germany
- University of Jena, Center for Biomedical Optics and Photonics, Jena, Germany
- Address all correspondence to: Martin Hammer, E-mail:
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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: 2.0] [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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Andersen KM, Sauer L, Gensure RH, Hammer M, Bernstein PS. Characterization of Retinitis Pigmentosa Using Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO). Transl Vis Sci Technol 2018; 7:20. [PMID: 29946494 PMCID: PMC6016507 DOI: 10.1167/tvst.7.3.20] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/16/2018] [Indexed: 02/06/2023] Open
Abstract
PURPOSE We investigated fundus autofluorescence (FAF) lifetimes in patients with retinitis pigmentosa (RP) using fluorescence lifetime imaging ophthalmoscopy (FLIO). METHODS A total of 33 patients (mean age, 40.0 ± 17.0 years) with RP and an age-matched healthy group were included. The Heidelberg FLIO was used to detect FAF decays in short (SSC; 498-560 nm) and long (LSC; 560-720 nm) spectral channels. We investigated a 30° retinal field and calculated the amplitude-weighted mean fluorescence lifetime (τm). Additionally, macular pigment measurements, macular optical coherence tomography (OCT) scans, fundus photographs, visual fields, and fluorescein angiograms were recorded. Genetic studies were performed on nearly all patients. RESULTS In RP, FLIO shows a typical pattern of prolonged τm in atrophic regions in the outer macula (SSC, 419 ± 195 ps; LSC, 401 ± 111 ps). Within the relatively preserved retina in the macular region, ring-shaped patterns were found, most distinctive in patients with autosomal dominant RP inheritance. Mean FAF lifetimes were shortened in rings in the LSC. Central areas remained relatively unaffected. CONCLUSIONS FLIO uniquely presents a distinct and specific signature in eyes affected with RP. The ring patterns show variations that indicate genetically determined pathologic processes. Shortening of FAF lifetimes in the LSC may indicate disease progression, as was previously demonstrated for Stargardt disease. Therefore, FLIO might be able to indicate disease progression in RP as well. TRANSLATIONAL RELEVANCE Hyperfluorescent FLIO rings with short FAF lifetimes may provide insight into the pathophysiologic disease status of RP-affected retinas potentially providing a more detailed assessment of disease progression.
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Affiliation(s)
- Karl M. Andersen
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
- Geisinger Commonwealth School of Medicine, Scranton, PA, USA
| | - Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | | | - Martin Hammer
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Paul S. Bernstein
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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Sauer L, Gensure RH, Hammer M, Bernstein PS. Fluorescence Lifetime Imaging Ophthalmoscopy: A Novel Way to Assess Macular Telangiectasia Type 2. Ophthalmol Retina 2018; 2:587-598. [PMID: 30116796 PMCID: PMC6089530 DOI: 10.1016/j.oret.2017.10.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE Macular Telangiectasia Type 2 (MacTel) is an uncommon, late-onset complex retinal disease that leads to central vision loss. No causative gene(s) have been identified so far, resulting in a challenging clinical diagnostic dilemma because retinal changes of early stages are often subtle. The objective of this study was to investigate the benefit of fluorescence lifetime imaging ophthalmoscopy (FLIO) for retinal imaging in patients with MacTel. DESIGN Cross-sectional study from a tertiary-care retinal referral practice. SUBJECTS AND CONTROLS 42 eyes of 21 patients (mean age 60.5±13.3 years) with MacTel as well as an age-matched healthy control group (42 eyes of 25 subjects, mean age 60.8±13.4 years). METHODS A 30° retinal field centered at the fovea was investigated using FLIO. This camera is based on a Heidelberg Engineering Spectralis system. Fundus autofluorescence (FAF) decays were detected in short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channels. The mean fluorescence lifetime, τm, was calculated from a 3-exponential approximation of the FAF decays. For MacTel patients, macular pigment (MP), OCT, blue light reflectance, fluorescein angiography, as well as fundus photography, were also recorded. MAIN OUTCOME MEASURES Mean FAF lifetime (τm) images. RESULTS FLIO of MacTel patients shows a unique pattern of prolonged τm at the temporal side of the fovea in patients with MacTel in the "MacTel area" within 5-6° of the foveal center. In early stages, this region appears crescent-shaped, while advanced stages show a ring-like pattern. This pattern corresponds well with other imaging modalities and gives an especially high contrast of the affected region even in minimally affected individuals. Additionally, FLIO provides a novel means to monitor the abnormal MP distribution. In one case, FLIO showed changes suggestive of MacTel within a clinically normal parent of two MacTel patients. CONCLUSIONS FLIO detects retinal changes in patients with MacTel with high contrast, presenting a distinctive signature that is a characteristic finding of the disease. The non-invasive properties of this novel imaging modality provide a valuable addition to clinical assessment of early changes in the disease that could lead to more accurate diagnosis of MacTel.
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Affiliation(s)
- Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
- University Hospital Jena, Bachstraße 18, 07743, Jena, Germany
| | | | - Martin Hammer
- University Hospital Jena, Bachstraße 18, 07743, Jena, Germany
| | - Paul S. Bernstein
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
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Sauer L, Andersen KM, Li B, Gensure RH, Hammer M, Bernstein PS. Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) of Macular Pigment. Invest Ophthalmol Vis Sci 2018; 59:3094-3103. [PMID: 30025128 PMCID: PMC6009392 DOI: 10.1167/iovs.18-23886] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/04/2018] [Indexed: 02/04/2023] Open
Abstract
Purpose To describe different patterns of macular pigment (MP) seen in fluorescence lifetime imaging ophthalmoscopy (FLIO) and to analyze ex vivo fluorescence characteristics of carotenoids. Methods A total of 31 eyes of young healthy subjects, 4 eyes from patients with albinism, 36 eyes with macular telangiectasia type 2 (MacTel), 24 eyes with retinitis pigmentosa, and 1 eye with a macular hole were included in this clinic-based, cross-sectional study. All subjects underwent Heidelberg Engineering FLIO and MP measurements (dual-wavelength autofluorescence). Fundus autofluorescence (FAF) lifetimes of a 30° retinal field were detected in two spectral channels (SSC: 498-560 nm; LSC: 560-720 nm), and amplitude-weighted mean fluorescence lifetimes (τm) were calculated. Additionally, autofluorescence lifetimes of known dilutions of lutein and zeaxanthin were measured in a cuvette in free- and protein-associated states. Results MP shows a significant inverse correlation to foveal FAF lifetimes measured with FLIO (SSC: r = -0.608; P < 0.001). Different distribution patterns can be assigned to specific disease-related changes. Two patients with albinism, who did not have MP, were found to be missing short FAF lifetimes. In solvent, lutein and zeaxanthin show very short autofluorescence lifetimes (∼50-60 ps; SSC), as do their respective binding proteins (∼40-50 ps; SSC). When combining carotenoids with their specific binding proteins, the decay times shift to longer means (∼70-90 ps; SSC). Conclusions This study expands upon previous findings of an impact of MP on short FAF lifetimes by describing ex vivo autofluorescence lifetimes of carotenoids and different in vivo autofluorescence patterns that can be associated with certain diseases.
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Affiliation(s)
- Lydia Sauer
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Karl M. Andersen
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
- Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania, United States
| | - Binxing Li
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Rebekah H. Gensure
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Martin Hammer
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Paul S. Bernstein
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
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Sauer L, Klemm M, Peters S, Schweitzer D, Schmidt J, Kreilkamp L, Ramm L, Meller D, Hammer M. Monitoring foveal sparing in geographic atrophy with fluorescence lifetime imaging ophthalmoscopy - a novel approach. Acta Ophthalmol 2018; 96:257-266. [PMID: 29105362 DOI: 10.1111/aos.13587] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 08/09/2017] [Indexed: 01/12/2023]
Abstract
PURPOSE To investigate fundus autofluorescence (FAF) lifetimes in geographic atrophy (GA) with a focus on macular pigment (MP) and foveal sparing. METHODS The study included 35 eyes from 28 patients (mean age 79.2 ± 8.0 years) with GA. A 30° retinal field, centred at the macula, was investigated using fluorescence lifetime imaging ophthalmoscopy (FLIO). The FLIO technology is based on a Heidelberg Engineering Spectralis system. Decays of FAF were detected in a short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channel. The mean fluorescence lifetime, τm , was calculated from a three-exponential approximation of the FAF decays. Macular optical coherence tomography (OCT) scans as well as fundus photography were recorded. RESULTS Review of FLIO data reveals specific patterns of significantly prolonged τm in regions of GA (SSC 616 ± 343 ps, LSC 615 ± 154 ps) as compared to non-atrophic regions. Large τm differences between the fovea and atrophic areas correlate with better visual acuity (VA). Shorter τm at the fovea than within other non-atrophic regions indicates sparing, which was identified in 16 eyes. Seventy per cent of patients treated with lutein supplementation showed foveal sparing, whereas the rate among non-supplemented patients was 22%. CONCLUSION Using FLIO, we present a novel way to detect foveal sparing, investigate MP, and analyse variability of τm in different foveal regions (including the prognostic valuable border region) in GA. These findings support the potential utility of FLIO in monitoring disease progression. The findings also highlight the possibly protective effect of lutein supplementation, with implication in recording the presence and distributional pattern of MP.
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Affiliation(s)
| | - Matthias Klemm
- Institute of Biomedical Engineering and Informatics; Technical University Ilmenau; Ilmenau Germany
| | | | - Dietrich Schweitzer
- University Hospital Jena; Jena Germany
- Center for Medical Optics and Photonics; University of Jena; Jena Germany
| | | | | | - Lisa Ramm
- Department of Ophthalmology; University Hospital Carl-Gustav Carus; TU Dresden; Dresden Germany
| | | | - Martin Hammer
- University Hospital Jena; Jena Germany
- Center for Medical Optics and Photonics; University of Jena; Jena Germany
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Le Marois A, Suhling K. Quantitative Live Cell FLIM Imaging in Three Dimensions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1035:31-48. [PMID: 29080129 DOI: 10.1007/978-3-319-67358-5_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In this chapter, the concept of fluorescence lifetime and its utility in quantitative live cell imaging will be introduced, along with methods to record and analyze FLIM data. Relevant applications in 3D tissue and live cell imaging, including multiplexed FLIM detection, will also be detailed.
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Affiliation(s)
- Alix Le Marois
- Department of Physics, King's College London, Strand, London, WC2R 2LS, UK
| | - Klaus Suhling
- Department of Physics, King's College London, Strand, London, WC2R 2LS, UK.
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Sauer L, Gensure RH, Andersen KM, Kreilkamp L, Hageman GS, Hammer M, Bernstein PS. Patterns of Fundus Autofluorescence Lifetimes In Eyes of Individuals With Nonexudative Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2018; 59:AMD65-AMD77. [PMID: 30025104 PMCID: PMC6009207 DOI: 10.1167/iovs.17-23764] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 05/11/2018] [Indexed: 01/20/2023] Open
Abstract
Purpose To investigate fundus autofluorescence (FAF) lifetimes in patients with nonexudative AMD. Methods A total of 150 eyes of 110 patients (mean age: 73.2 ± 10.7 years) with nonexudative AMD, as well as a healthy group of 57 eyes in 38 subjects (mean age: 66.5 ± 8.7 years), were included. Investigations were conducted at the University Eye Clinic in Jena, Germany, as well as the Moran Eye Center in Salt Lake City, Utah, USA, using the Heidelberg Engineering Spectralis-based fluorescence lifetime imaging ophthalmoscope (FLIO). A 30° retinal field centered at the fovea was investigated. FAF decays were detected in short (498-560 nm) and long (560-720 nm, LSC) spectral channels. The mean fluorescence lifetimes (τm) were calculated. Optical coherence tomography scans and fundus photographs were also recorded. Results In patients with nonexudative AMD, FLIO shows a ring-shaped pattern of prolonged τm in the LSC. This pattern occurs in all patients with AMD (including very early stages) and in one-third of the healthy controls. FAF lifetimes were longer with more advanced stages. The presence of drusen is associated with prolonged τm when compared with the healthy fundus, but drusen identification is difficult with FLIO only. Conclusions FLIO detects a clear pattern of changes within the fundus, which appears to be AMD-associated. These changes are already visible in early AMD stages and not masked by the presence of other coexisting retinal diseases. These findings may be useful for the early diagnosis of AMD and to distinguish AMD from other retinal diseases.
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Affiliation(s)
- Lydia Sauer
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Rebekah H. Gensure
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Karl M. Andersen
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
- Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania, United States
| | - Lukas Kreilkamp
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Gregory S. Hageman
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
| | - Martin Hammer
- Department of Experimental Ophthalmology, University Hospital Jena, Jena, Germany
| | - Paul S. Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
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Peters S, Griebsch M, Klemm M, Haueisen J, Hammer M. Hydrogen peroxide modulates energy metabolism and oxidative stress in cultures of permanent human Müller cells MIO-M1. JOURNAL OF BIOPHOTONICS 2017; 10:1180-1188. [PMID: 27896951 DOI: 10.1002/jbio.201600201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 10/25/2016] [Accepted: 11/14/2016] [Indexed: 05/14/2023]
Abstract
In this study the influence of hydrogen peroxide (H2 O2 ) on the redox state, NADH protein binding, and mitochondrial membrane potential in Müller cells is investigated. Cultures of permanent human Müller cells MIO-M1 were exposed to H2 O2 in 75 µM and 150 µM concentration for two hours. Fluorescence emission spectra and lifetimes were measured by two-photon microscopy (excitation wavelength: 740 nm) at the mitochondria which were identified in the microscopic images by their fluorescence properties (spectra and intensity). Two hours of H2 O2 exposure did not impair viability of MIO-M1 cells in culture. Whereas the ratio of flavine- to NADH fluorescence intensity did not change under either H2 O2 concentration, the mean lifetime was significantly different between controls, not exposed to H2 O2 , and the 150 µM H2 O2 exposure (972 ± 63 ps vs. 1152 ± 64 ps, p = 0.014). One hour after cessation of the H2 O2 exposure, the value retuned to that of the control (983 ± 36 ps). A hyperpolarization of the mitochondrial membrane under 150 µM H2 O2 was found. These findings suggest a shift form free to protein-bound NADH in mitochondria as well as a hyperpolarization of their inner membrane which could be related to an impairment of Müller cell function despite their preserved viability. Exposure of human Müller cells to hydrogen peroxide for two hours results in a reversible change of protein binding of mitochondrial NADH upon unchanged redox ratio. The mitochondrial membrane potential is increased during exposure.
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Affiliation(s)
- Sven Peters
- University Hospital Jena, Department of Ophthalmology, 07743, Jena, Germany
| | - Max Griebsch
- University Hospital Jena, Department of Ophthalmology, 07743, Jena, Germany
| | - Matthias Klemm
- Technical University Ilmenau, Int. for Biomedical Engineering and Informatics, Gustav-Kirchhoff-Str. 2, 98693, Ilmenau, Germany
| | - Jens Haueisen
- Technical University Ilmenau, Int. for Biomedical Engineering and Informatics, Gustav-Kirchhoff-Str. 2, 98693, Ilmenau, Germany
| | - Martin Hammer
- University Hospital Jena, Department of Ophthalmology, 07743, Jena, Germany
- University of Jena, Center for Biomedical Optics and Photonics, 07740, Jena, Germany
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Dysli C, Wolf S, Berezin MY, Sauer L, Hammer M, Zinkernagel MS. Fluorescence lifetime imaging ophthalmoscopy. Prog Retin Eye Res 2017; 60:120-143. [PMID: 28673870 PMCID: PMC7396320 DOI: 10.1016/j.preteyeres.2017.06.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/19/2017] [Accepted: 06/29/2017] [Indexed: 12/17/2022]
Abstract
Imaging techniques based on retinal autofluorescence have found broad applications in ophthalmology because they are extremely sensitive and noninvasive. Conventional fundus autofluorescence imaging measures fluorescence intensity of endogenous retinal fluorophores. It mainly derives its signal from lipofuscin at the level of the retinal pigment epithelium. Fundus autofluorescence, however, can not only be characterized by the spatial distribution of the fluorescence intensity or emission spectrum, but also by a characteristic fluorescence lifetime function. The fluorescence lifetime is the average amount of time a fluorophore remains in the excited state following excitation. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an emerging imaging modality for in vivo measurement of lifetimes of endogenous retinal fluorophores. Recent reports in this field have contributed to our understanding of the pathophysiology of various macular and retinal diseases. Within this review, the basic concept of fluorescence lifetime imaging is provided. It includes technical background information and correlation with in vitro measurements of individual retinal metabolites. In a second part, clinical applications of fluorescence lifetime imaging and fluorescence lifetime features of selected retinal diseases such as Stargardt disease, age-related macular degeneration, choroideremia, central serous chorioretinopathy, macular holes, diabetic retinopathy, and retinal artery occlusion are discussed. Potential areas of use for fluorescence lifetime imaging ophthalmoscopy will be outlined at the end of this review.
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Affiliation(s)
- Chantal Dysli
- Department of Ophthalmology and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Sebastian Wolf
- Department of Ophthalmology and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Mikhail Y Berezin
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Lydia Sauer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Martin Hammer
- Department of Ophthalmology, University Hospital Jena, Jena, Germany
| | - Martin S Zinkernagel
- Department of Ophthalmology and Department of Clinical Research, Inselspital, Bern University Hospital, University of Bern, Switzerland.
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Sauer L, Peters S, Schmidt J, Schweitzer D, Klemm M, Ramm L, Augsten R, Hammer M. Monitoring macular pigment changes in macular holes using fluorescence lifetime imaging ophthalmoscopy. Acta Ophthalmol 2017; 95:481-492. [PMID: 27775222 DOI: 10.1111/aos.13269] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 08/12/2016] [Indexed: 01/19/2023]
Abstract
PURPOSE To investigate the impact of macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo by characterizing full-thickness idiopathic macular holes (MH) and macular pseudo-holes (MPH). METHODS A total of 37 patients with MH and 52 with MPH were included. Using the fluorescence lifetime imaging ophthalmoscope (FLIO), based on a Heidelberg Engineering Spectralis system, a 30° retinal field was investigated. FAF decays were detected in a short (498-560 nm; ch1) and long (560-720 nm; ch2) wavelength channel. τm , the mean fluorescence lifetime, was calculated from a three-exponential approximation of the FAF decays. Macular coherence tomography scans were recorded, and macular pigment's optical density (MPOD) was measured (one-wavelength reflectometry). Two MH subgroups were analysed according to the presence or absence of an operculum above the MH. A total of 17 healthy fellow eyes were included. A longitudinal FAF decay examination was conducted in nine patients, which were followed up after surgery and showed a closed MH. RESULTS In MH without opercula, significant τm differences (p < 0.001) were found between the hole area (MHa) and surrounding areas (MHb) (ch1: MHa 238 ± 64 ps, MHb 181 ± 78 ps; ch2: MHa 275 ± 49 ps, MHb 223 ± 48 ps), as well as between MHa and healthy eyes or closed MH. Shorter τm , adjacent to the hole, can be assigned to areas with equivalently higher MPOD. Opercula containing MP also show short τm . In MPH, the intactness of the Hele fibre layer is associated with shortest τm . CONCLUSIONS Shortest τm originates from MP-containing retinal layers, especially from the Henle fibre layer. Fluorescence lifetime imaging ophthalmoscope (FLIO) provides information on the MP distribution, the pathogenesis and topology of MH. Macular pigment (MP) fluorescence may provide a biomarker for monitoring pathological changes in retinal diseases.
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Affiliation(s)
- Lydia Sauer
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Sven Peters
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Johanna Schmidt
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | | | - Matthias Klemm
- Institute of Biomedical Engineering and Informatics; Technical University Ilmenau; Ilmenau Germany
| | - Lisa Ramm
- Department of Ophthalmology; University Hospital Carl-Gustav Carus; TU Dresden Germany
| | - Regine Augsten
- Department of Ophthalmology; University Hospital Jena; Jena Germany
| | - Martin Hammer
- Department of Ophthalmology; University Hospital Jena; Jena Germany
- Center for Medical Optics and Photonics; University of Jena; Jena Germany
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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: 1.5] [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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Klemm M, Blum J, Link D, Hammer M, Haueisen J, Schweitzer D. Combination of confocal principle and aperture stop separation improves suppression of crystalline lens fluorescence in an eye model. BIOMEDICAL OPTICS EXPRESS 2016; 7:3198-3210. [PMID: 27699092 PMCID: PMC5030004 DOI: 10.1364/boe.7.003198] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 05/21/2023]
Abstract
Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a new technique to detect changes in the human retina. The autofluorescence decay over time, generated by endogenous fluorophores, is measured in vivo. The strong autofluorescence of the crystalline lens, however, superimposes the intensity decay of the retina fluorescence, as the confocal principle is not able to suppress it sufficiently. Thus, the crystalline lens autofluorescence causes artifacts in the retinal fluorescence lifetimes determined from the intensity decays. Here, we present a new technique to suppress the autofluorescence of the crystalline lens by introducing an annular stop into the detection light path, which we call Schweitzer's principle. The efficacy of annular stops with an outer diameter of 7 mm and inner diameters of 1 to 5 mm are analyzed in an experimental setup using a model eye based on fluorescent dyes. Compared to the confocal principle, Schweitzer's principle with an inner diameter of 3 mm is able to reduce the simulated crystalline lens fluorescence to 4%, while 42% of the simulated retina fluorescence is preserved. Thus, we recommend the implementation of Schweitzer's principle in scanning laser ophthalmoscopes used for fundus autofluorescence measurements, especially the FLIO device, for improved image quality.
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Affiliation(s)
- Matthias Klemm
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Johannes Blum
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Dietmar Link
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Martin Hammer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740 Jena, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, POB 100565, 98694 Ilmenau, Germany
| | - Dietrich Schweitzer
- Experimental Ophthalmology, University Hospital Jena, Bachstraße 18, 07740 Jena, Germany
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