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Kunala K, Tang JAH, Bowles Johnson KE, Huynh KT, Parkins K, Kim HJ, Yang Q, Sparrow JR, Hunter JJ. Near Infrared Autofluorescence Lifetime Imaging of Human Retinal Pigment Epithelium Using Adaptive Optics Scanning Light Ophthalmoscopy. Invest Ophthalmol Vis Sci 2024; 65:27. [PMID: 38758638 PMCID: PMC11107951 DOI: 10.1167/iovs.65.5.27] [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: 08/07/2023] [Accepted: 04/23/2024] [Indexed: 05/19/2024] Open
Abstract
Purpose To demonstrate the first near-infrared adaptive optics fluorescence lifetime imaging ophthalmoscopy (NIR-AOFLIO) measurements in vivo of the human retinal pigment epithelial (RPE) cellular mosaic and to visualize lifetime changes at different retinal eccentricities. Methods NIR reflectance and autofluorescence were captured using a custom adaptive optics scanning light ophthalmoscope in 10 healthy subjects (23-64 years old) at seven eccentricities and in two eyes with retinal abnormalities. Repeatability was assessed across two visits up to 8 weeks apart. Endogenous retinal fluorophores and hydrophobic whole retinal extracts of Abca4-/- pigmented and albino mice were imaged to probe the fluorescence origin of NIR-AOFLIO. Results The RPE mosaic was resolved at all locations in five of seven younger subjects (<35 years old). The mean lifetime across near-peripheral regions (8° and 12°) was longer compared to near-foveal regions (0° and 2°). Repeatability across two visits showed moderate to excellent correlation (intraclass correlation: 0.88 [τm], 0.75 [τ1], 0.65 [τ2], 0.98 [a1]). The mean lifetime across drusen-containing eyes was longer than in age-matched healthy eyes. Fluorescence was observed in only the extracts from pigmented Abca4-/- mouse. Conclusions NIR-AOFLIO was repeatable and allowed visualization of the RPE cellular mosaic. An observed signal in only the pigmented mouse extract infers the fluorescence signal originates predominantly from melanin. Variations observed across the retina with intermediate age-related macular degeneration suggest NIR-AOFLIO may act as a functional measure of a biomarker for in vivo monitoring of early alterations in retinal health.
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Affiliation(s)
- Karteek Kunala
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Byers Eye Institute, Stanford University, Palo Alto, California, United States
| | - Janet A. H. Tang
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Kristen E. Bowles Johnson
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Khang T. Huynh
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, Berkeley, California, United States
| | - Keith Parkins
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Hye-Jin Kim
- College of Pharmacy, Keimyung University, Dalseo-gu, Daegu, South Korea
- Department of Ophthalmology, Columbia University Medical Center, New York, New York, United States
| | - Qiang Yang
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Janet R. Sparrow
- Department of Ophthalmology, Columbia University Medical Center, New York, New York, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Kaushik V, Dąbrowski M, Gessa L, Kumar N, Fernandes H. Two-photon excitation fluorescence in ophthalmology: safety and improved imaging for functional diagnostics. Front Med (Lausanne) 2024; 10:1293640. [PMID: 38235268 PMCID: PMC10791900 DOI: 10.3389/fmed.2023.1293640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/11/2023] [Indexed: 01/19/2024] Open
Abstract
Two-photon excitation fluorescence (TPEF) is emerging as a powerful imaging technique with superior penetration power in scattering media, allowing for functional imaging of biological tissues at a subcellular level. TPEF is commonly used in cancer diagnostics, as it enables the direct observation of metabolism within living cells. The technique is now widely used in various medical fields, including ophthalmology. The eye is a complex and delicate organ with multiple layers of different cell types and tissues. Although this structure is ideal for visual perception, it generates aberrations in TPEF eye imaging. However, adaptive optics can now compensate for these aberrations, allowing for improved imaging of the eyes of animal models for human diseases. The eye is naturally built to filter out harmful wavelengths, but these wavelengths can be mimicked and thereby utilized in diagnostics via two-photon (2Ph) excitation. Recent advances in laser-source manufacturing have made it possible to minimize the exposure of in vivo measurements within safety, while achieving sufficient signals to detect for functional images, making TPEF a viable option for human application. This review explores recent advances in wavefront-distortion correction in animal models and the safety of use of TPEF on human subjects, both of which make TPEF a potentially powerful tool for ophthalmological diagnostics.
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Affiliation(s)
- Vineeta Kaushik
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Michał Dąbrowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Luca Gessa
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Nelam Kumar
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Humberto Fernandes
- International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
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3
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Doyle HK, Herbeck SR, Boehm AE, Vanston JE, Ng R, Tuten WS, Roorda A. Boosting 2-photon vision with adaptive optics. J Vis 2023; 23:4. [PMID: 37801322 PMCID: PMC10561787 DOI: 10.1167/jov.23.12.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 09/05/2023] [Indexed: 10/07/2023] Open
Abstract
The 2-photon effect in vision occurs when two photons of the same wavelength are absorbed by cone photopigment in the retina and create a visual sensation matching the appearance of light close to half their wavelength. This effect is especially salient for infrared light, where humans are mostly insensitive to 1-photon isomerizations and thus any perception is dominated by 2-photon isomerizations. This phenomenon can be made more readily visible using short-pulsed lasers, which increase the likelihood of 2-photon excitation by making photon arrivals at the retina more concentrated in time. Adaptive optics provides another avenue for enhancing the 2-photon effect by focusing light more tightly at the retina, thereby increasing the spatial concentration of incident photons. This article makes three contributions. First, we demonstrate through color-matching experiments that an adaptive optics correction can provide a 25-fold increase in the luminance of the 2-photon effect-a boost equivalent to reducing pulse width by 96%. Second, we provide image-based evidence that the 2-photon effect occurs at the photoreceptor level. Third, we use our results to compute the specifications for a system that could utilize 2-photon vision and adaptive optics to image and stimulate the retina using a single infrared wavelength and reach luminance levels comparable to conventional displays.
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Affiliation(s)
- Hannah K Doyle
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA, USA
| | - Sofie R Herbeck
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA, USA
| | - Alexandra E Boehm
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA, USA
| | - John E Vanston
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA, USA
| | - Ren Ng
- Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA, USA
| | - William S Tuten
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, CA, USA
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4
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Kowalczuk L, Dornier R, Kunzi M, Iskandar A, Misutkova Z, Gryczka A, Navarro A, Jeunet F, Mantel I, Behar-Cohen F, Laforest T, Moser C. In Vivo Retinal Pigment Epithelium Imaging using Transscleral Optical Imaging in Healthy Eyes. OPHTHALMOLOGY SCIENCE 2022; 3:100234. [PMID: 36545259 PMCID: PMC9762198 DOI: 10.1016/j.xops.2022.100234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022]
Abstract
Objective To image healthy retinal pigment epithelial (RPE) cells in vivo using Transscleral OPtical Imaging (TOPI) and to analyze statistics of RPE cell features as a function of age, axial length (AL), and eccentricity. Design Single-center, exploratory, prospective, and descriptive clinical study. Participants Forty-nine eyes (AL: 24.03 ± 0.93 mm; range: 21.9-26.7 mm) from 29 participants aged 21 to 70 years (37.1 ± 13.3 years; 19 men, 10 women). Methods Retinal images, including fundus photography and spectral-domain OCT, AL, and refractive error measurements were collected at baseline. For each eye, 6 high-resolution RPE images were acquired using TOPI at different locations, one of them being imaged 5 times to evaluate the repeatability of the method. Follow-up ophthalmic examination was repeated 1 to 3 weeks after TOPI to assess safety. Retinal pigment epithelial images were analyzed with a custom automated software to extract cell parameters. Statistical analysis of the selected high-contrast images included calculation of coefficient of variation (CoV) for each feature at each repetition and Spearman and Mann-Whitney tests to investigate the relationship between cell features and eye and subject characteristics. Main Outcome Measures Retinal pigment epithelial cell features: density, area, center-to-center spacing, number of neighbors, circularity, elongation, solidity, and border distance CoV. Results Macular RPE cell features were extracted from TOPI images at an eccentricity of 1.6° to 16.3° from the fovea. For each feature, the mean CoV was < 4%. Spearman test showed correlation within RPE cell features. In the perifovea, the region in which images were selected for all participants, longer AL significantly correlated with decreased RPE cell density (R Spearman, Rs = -0.746; P < 0.0001) and increased cell area (Rs = 0.668; P < 0.0001), without morphologic changes. Aging was also significantly correlated with decreased RPE density (Rs = -0.391; P = 0.036) and increased cell area (Rs = 0.454; P = 0.013). Lower circular, less symmetric, more elongated, and larger cells were observed in those > 50 years. Conclusions The TOPI technology imaged RPE cells in vivo with a repeatability of < 4% for the CoV and was used to analyze the influence of physiologic factors on RPE cell morphometry in the perifovea of healthy volunteers. Financial Disclosures Proprietary or commercial disclosure may be found after the references.
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Key Words
- AF, autofluorescence
- AL, axial length
- AO, adaptive optics
- Adaptive Optics Transscleral Flood Illumination
- BCVA, best-corrected visual acuity
- CCS, center-to-center spacing
- CoV, coefficient of variation
- D, diopters
- FOV, field of view
- Healthy volunteers
- High resolution retinal imaging
- IOP, intraocular pressure
- NIR, near-infrared
- PRL, preferred retinal locus
- QC, quality criterion
- RE, refractive error
- RPE, retinal pigment epithelium
- Retinal Pigment Epithelium
- SD, standard deviation
- SLO, scanning laser ophthalmoscope
- TOPI, transscleral optical imaging
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Affiliation(s)
- Laura Kowalczuk
- Laboratory of Applied Photonic Devices, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland,Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland,Correspondence: Laura Kowalczuk, PhD, École Polytechnique Fédérale de Lausanne, School of Engineering, Institute of Electrical and Micro-engineering, Laboratory of Applied Photonics Devices, BM 4127, Station 17, CH-1015, Lausanne, Switzerland.
| | - Rémy Dornier
- Laboratory of Applied Photonic Devices, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Mathieu Kunzi
- Laboratory of Applied Photonic Devices, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Antonio Iskandar
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Zuzana Misutkova
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Aurélia Gryczka
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Aurélie Navarro
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Fanny Jeunet
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Irmela Mantel
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland,Jules-Gonin Eye Hospital, Fondation Asile des aveugles, Lausanne, Switzerland
| | - Francine Behar-Cohen
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris, France,INSERM U1138, USPC, Université de Paris-Cité, Sorbonne Université, Paris, France,Assistance Publique - Hôpitaux de Paris, Ophtalmopôle, Cochin Hospital, Paris, France,Université Paris Cité, Paris, France,Hôpital Foch, Suresnes, France
| | - Timothé Laforest
- Laboratory of Applied Photonic Devices, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christophe Moser
- Laboratory of Applied Photonic Devices, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Vienola KV, Zhang M, Snyder VC, Dansingani KK, Sahel JA, Rossi EA. Near infrared autofluorescence imaging of retinal pigmented epithelial cells using 663 nm excitation. Eye (Lond) 2022; 36:1878-1883. [PMID: 34462582 PMCID: PMC9499940 DOI: 10.1038/s41433-021-01754-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 08/03/2021] [Accepted: 08/18/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Fundus autofluorescence (AF) using adaptive optics scanning laser ophthalmoscopy (AOSLO) enables morphometric analysis of individual retinal pigmented epithelial (RPE) cells. However, only a few excitation wavelengths in the visible and near-infrared have been evaluated. Visible light excitation (<600 nm) presents additional safety hazards and is uncomfortable for patients. Near-infrared excitation (>700 nm) overcomes those problems but introduces others, including decreased AF signal and cone signatures that obscure RPE structure. Here we investigated the use of an intermediate wavelength, 663 nm, for excitation and compared it to 795 nm. METHODS Subjects were imaged using AOSLO equipped with a detection channel to collect AF emission between 814 and 850 nm. Two light sources (663 and 795 nm) were used to excite the retinal fluorophores. We recorded 90 s videos and registered them with custom software to integrate AF images for analysis. RESULTS We imaged healthy eyes and an eye with pattern dystrophy. Similar AF microstructures were detected with each excitation source, despite ~4 times lower excitation power with 663 nm. The signal-to-noise values showed no meaningful difference between 663 nm and 795 nm excitation and a similar trend was observed for image contrast between the two excitation wavelengths. CONCLUSIONS Lower light levels can be used with shorter wavelength excitation to achieve comparable images of the microstructure of the RPE as have been obtained using higher light levels at longer wavelengths. Further experiments are needed to fully characterize AF across spectrum and determine the optimal excitation and emission bandwidths that balance efficiency, patient comfort, and efficacy.
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Affiliation(s)
- Kari V Vienola
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA, USA.
| | - Min Zhang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Valerie C Snyder
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kunal K Dansingani
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ethan A Rossi
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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6
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Tang JAH, Granger CE, Kunala K, Parkins K, Huynh KT, Bowles-Johnson K, Yang Q, Hunter JJ. Adaptive optics fluorescence lifetime imaging ophthalmoscopy of in vivo human retinal pigment epithelium. BIOMEDICAL OPTICS EXPRESS 2022; 13:1737-1754. [PMID: 35414970 PMCID: PMC8973160 DOI: 10.1364/boe.451628] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 05/18/2023]
Abstract
The intrinsic fluorescence properties of lipofuscin - naturally occurring granules that accumulate in the retinal pigment epithelium - are a potential biomarker for the health of the eye. A new modality is described here which combines adaptive optics technology with fluorescence lifetime detection, allowing for the investigation of functional and compositional differences within the eye and between subjects. This new adaptive optics fluorescence lifetime imaging ophthalmoscope was demonstrated in 6 subjects. Repeated measurements between visits had a minimum intraclass correlation coefficient of 0.59 Although the light levels were well below maximum permissible exposures, the safety of the imaging paradigm was tested using clinical measures; no concerns were raised. This new technology allows for in vivo adaptive optics fluorescence lifetime imaging of the human RPE mosaic.
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Affiliation(s)
- Janet A. H. Tang
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Contributed equally
| | - Charles E. Granger
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Contributed equally
| | - Karteek Kunala
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Keith Parkins
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Khang T. Huynh
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Kristen Bowles-Johnson
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
| | - Qiang Yang
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Jennifer J. Hunter
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14627, USA
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7
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Boguslawski J, Palczewska G, Tomczewski S, Milkiewicz J, Kasprzycki P, Stachowiak D, Komar K, Marzejon MJ, Sikorski BL, Hudzikowski A, Głuszek A, Łaszczych Z, Karnowski K, Soboń G, Palczewski K, Wojtkowski M. In vivo imaging of the human eye using a two-photon excited fluorescence scanning laser ophthalmoscope. J Clin Invest 2021; 132:154218. [PMID: 34847075 PMCID: PMC8759795 DOI: 10.1172/jci154218] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Noninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, are highly sensitive to UV light; thus, safe analyses of these processes in humans are currently beyond the reach of even the most modern ocular imaging modalities. METHODS We present a compact fluorescence scanning laser ophthalmoscope (TPEF-SLO) and spectrally resolved images of the human retina based on two-photon excitation (TPE) with near-infrared (IR) light. A custom Er:fiber laser with integrated pulse selection, along with intelligent post-processing of data, enables excitation with low laser power and precise measurement of weak signals. RESULTS We demonstrate spectrally resolved TPE fundus images of human subjects. Comparison of TPE data between human and mouse models of retinal diseases revealed similarity with mouse models that rapidly accumulate bisretinoid condensation products. Thus, visual cycle intermediates and toxic byproducts of this metabolic pathway can be measured and quantified by TPE imaging. CONCLUSION Our work establishes a TPE instrument and measurement method for noninvasive metabolic assessment of the human retina. This approach opens the possibility for monitoring eye diseases in the earliest stages before structural damage to the retina occurs. FUNDING NIH, Research to Prevent Blindness, Foundation for Polish Science, European Regional Development Fund, Polish National Agency for Academic Exchange and Polish Ministry of Science and Higher Education.
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Affiliation(s)
- Jakub Boguslawski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Grazyna Palczewska
- Department of Medical Devices, Polgenix, Inc., Cleveland, United States of America
| | - Slawomir Tomczewski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Jadwiga Milkiewicz
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Piotr Kasprzycki
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Dorota Stachowiak
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Katarzyna Komar
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Marcin J Marzejon
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Bartosz L Sikorski
- Department of Ophthalmology, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Arkadiusz Hudzikowski
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Aleksander Głuszek
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Zbigniew Łaszczych
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Karol Karnowski
- International Center for Translational Eye Research, Polish Academy of Sciences, Warsaw, Poland
| | - Grzegorz Soboń
- Faculty of Electronics, Wrocław University of Science and Technology, Wroclaw, Poland
| | - Krzysztof Palczewski
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Maciej Wojtkowski
- Physical Chemistry of Biological Systems, Polish Academy of Sciences, Warsaw, Poland
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8
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Wynne N, Carroll J, Duncan JL. Promises and pitfalls of evaluating photoreceptor-based retinal disease with adaptive optics scanning light ophthalmoscopy (AOSLO). Prog Retin Eye Res 2020; 83:100920. [PMID: 33161127 DOI: 10.1016/j.preteyeres.2020.100920] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/28/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022]
Abstract
Adaptive optics scanning light ophthalmoscopy (AOSLO) allows visualization of the living human retina with exquisite single-cell resolution. This technology has improved our understanding of normal retinal structure and revealed pathophysiological details of a number of retinal diseases. Despite the remarkable capabilities of AOSLO, it has not seen the widespread commercial adoption and mainstream clinical success of other modalities developed in a similar time frame. Nevertheless, continued advancements in AOSLO hardware and software have expanded use to a broader range of patients. Current devices enable imaging of a number of different retinal cell types, with recent improvements in stimulus and detection schemes enabling monitoring of retinal function, microscopic structural changes, and even subcellular activity. This has positioned AOSLO for use in clinical trials, primarily as exploratory outcome measures or biomarkers that can be used to monitor disease progression or therapeutic response. AOSLO metrics could facilitate patient selection for such trials, to refine inclusion criteria or to guide the choice of therapy, depending on the presence, absence, or functional viability of specific cell types. Here we explore the potential of AOSLO retinal imaging by reviewing clinical applications as well as some of the pitfalls and barriers to more widespread clinical adoption.
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Affiliation(s)
- Niamh Wynne
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Joseph Carroll
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, CA, USA.
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AbdelAl O, Ashraf M, Sampani K, Sun JK. "For Mass Eye and Ear Special Issue" Adaptive Optics in the Evaluation of Diabetic Retinopathy. Semin Ophthalmol 2019; 34:189-197. [PMID: 31188056 DOI: 10.1080/08820538.2019.1620794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Retinal imaging is a fundamental tool for clinical and research efforts in the evaluation and management of diabetic retinopathy. Adaptive optics (AO) is an imaging technique that enables correction of over 90% of the optical aberrations of an individual eye induced primarily by the tear film, cornea and lens. The two major tasks of any AO system are to measure the optical imperfections of the eye and to then compensate for these aberrations to generate a corrected wavefront of reflected light from the eye. AO scanning laser ophthalmoscopy (AOSLO) provides a theoretical lateral resolution limit of 1.4 μm, allowing the study of microscopic features of the retinal vascular and neural tissue. AOSLO studies have revealed irregularities of the photoreceptor mosaic, vascular loss, and details of vascular lesions in diabetic eyes that may provide new insight into development, regression, and response to therapy of diabetic eye disease.
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Affiliation(s)
- Omar AbdelAl
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
| | - Mohammed Ashraf
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
| | - Konstantina Sampani
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,c Department of Medicine , Harvard Medical School , Boston , MA , USA
| | - Jennifer K Sun
- a Beetham Eye Institute , Joslin Diabetes Center , Boston , MA , USA.,b Department of Ophthalmology , Harvard Medical School , Boston , MA , USA
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10
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Granger CE, Yang Q, Song H, Saito K, Nozato K, Latchney LR, Leonard BT, Chung MM, Williams DR, Rossi EA. Human Retinal Pigment Epithelium: In Vivo Cell Morphometry, Multispectral Autofluorescence, and Relationship to Cone Mosaic. Invest Ophthalmol Vis Sci 2019; 59:5705-5716. [PMID: 30513531 PMCID: PMC6280915 DOI: 10.1167/iovs.18-24677] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Purpose To characterize in vivo morphometry and multispectral autofluorescence of the retinal pigment epithelial (RPE) cell mosaic and its relationship to cone cell topography across the macula. Methods RPE cell morphometrics were computed in regularly spaced regions of interest (ROIs) from contiguous short-wavelength autofluorescence (SWAF) and photoreceptor reflectance images collected across the macula in one eye of 10 normal participants (23–65 years) by using adaptive optics scanning light ophthalmoscopy (AOSLO). Infrared autofluorescence (IRAF) images of the RPE were collected with AOSLO in seven normal participants (22–65 years), with participant overlap, and compared to SWAF quantitatively and qualitatively. Results RPE cell statistics could be analyzed in 84% of SWAF ROIs. RPE cell density consistently decreased with eccentricity from the fovea (participant mean ± SD: 6026 ± 1590 cells/mm2 at fovea; 4552 ± 1370 cells/mm2 and 3757 ± 1290 cells/mm2 at 3.5 mm temporally and nasally, respectively). Mean cone-to-RPE cell ratio decreased rapidly from 16.6 at the foveal center to <5 by 1 mm. IRAF revealed cells in six of seven participants, in agreement with SWAF RPE cell size and location. Differences in cell fluorescent structure, contrast, and visibility beneath vasculature were observed between modalities. Conclusions Improvements in AOSLO autofluorescence imaging permit efficient visualization of RPE cells with safe light exposures, allowing individual characterization of RPE cell morphometry that is variable between participants. The normative dataset and analysis of RPE cell IRAF and SWAF herein are essential for understanding microscopic characteristics of cell fluorescence and may assist in interpreting disease progression in RPE cells.
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Affiliation(s)
- Charles E Granger
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Qiang Yang
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Hongxin Song
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, National Engineering Research Center for Ophthalmic Equipment, Beijing, China
| | - Kenichi Saito
- Canon U.S.A., Inc., Melville, New York, United States
| | - Koji Nozato
- Canon U.S.A., Inc., Melville, New York, United States
| | - Lisa R Latchney
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York, United States
| | - Bianca T Leonard
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Mina M Chung
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,Flaum Eye Institute, University of Rochester Medical Center, Rochester, New York, United States
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States.,The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Ethan A Rossi
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States.,Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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11
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Walters S, Schwarz C, Sharma R, Rossi EA, Fischer WS, DiLoreto DA, Strazzeri J, Nelidova D, Roska B, Hunter JJ, Williams DR, Merigan WH. Cellular-scale evaluation of induced photoreceptor degeneration in the living primate eye. BIOMEDICAL OPTICS EXPRESS 2019; 10:66-82. [PMID: 30775083 PMCID: PMC6363191 DOI: 10.1364/boe.10.000066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 05/06/2023]
Abstract
Progress is needed in developing animal models of photoreceptor degeneration and evaluating such models with longitudinal, noninvasive techniques. We employ confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT) and high-resolution retinal imaging to noninvasively observe the retina of non-human primates with induced photoreceptor degeneration. Photoreceptors were imaged at the single-cell scale in three modalities of adaptive optics scanning light ophthalmoscopy: traditional confocal reflectance, indicative of waveguiding; a non-confocal offset aperture technique visualizing scattered light; and two-photon excited fluorescence, the time-varying signal of which, at 730 nm excitation, is representative of visual cycle function. Assessment of photoreceptor structure and function using these imaging modalities revealed a reduction in retinoid production in cone photoreceptor outer segments while inner segments appeared to remain present. Histology of one retina confirmed loss of outer segments and the presence of intact inner segments. This unique combination of imaging modalities can provide essential, clinically-relevant information on both the structural integrity and function of photoreceptors to not only validate models of photoreceptor degeneration but potentially evaluate the efficacy of future cell and gene-based therapies for vision restoration.
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Affiliation(s)
- Sarah Walters
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with the Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with Facebook Reality Labs, Redmond, WA, USA
| | - Ethan A. Rossi
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Currently with the Departments of Ophthalmology & Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Jennifer Strazzeri
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Dasha Nelidova
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jennifer J. Hunter
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - William H. Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
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12
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Grieve K, Gofas-Salas E, Ferguson RD, Sahel JA, Paques M, Rossi EA. In vivo near-infrared autofluorescence imaging of retinal pigment epithelial cells with 757 nm excitation. BIOMEDICAL OPTICS EXPRESS 2018; 9:5946-5961. [PMID: 31065405 PMCID: PMC6490976 DOI: 10.1364/boe.9.005946] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 05/06/2023]
Abstract
We demonstrate near-infrared autofluorescence (NIRAF) imaging of retinal pigment epithelial (RPE) cells in vivo in healthy volunteers and patients using a 757 nm excitation source in adaptive optics scanning laser ophthalmoscopy (AOSLO). NIRAF excited at 757 nm and collected in an emission band from 778 to 810 nm produced a robust NIRAF signal, presumably arising from melanin, and revealed the typical hexagonal mosaic of RPE cells at most eccentricities imaged within the macula of normal eyes. Several patterns of altered NIRAF structure were seen in patients, including disruption of the NIRAF over a drusen, diffuse hyper NIRAF signal with loss of individual cell delineation in a case of non-neovascular age-related macular degeneration (AMD), and increased visibility of the RPE mosaic under an area showing loss of photoreceptors. In some participants, a superposed cone mosaic was clearly visible in the fluorescence channel at eccentricities between 2 and 6° from the fovea. This was reproducible in these participants and existed despite the use of emission filters with an optical attenuation density of 12 at the excitation wavelength, minimizing the possibility that this was due to bleed through of the excitation light. This cone signal may be a consequence of cone waveguiding on either the ingoing excitation light and/or the outgoing NIRAF emitted by fluorophores within the RPE and/or choroid and warrants further investigation. NIRAF imaging at 757 nm offers efficient signal excitation and detection, revealing structural alterations in retinal disease with good contrast and shows promise as a tool for monitoring future therapies at the level of single RPE cells.
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Affiliation(s)
- Kate Grieve
- Vision Institute and Quinze Vingts National Ophthalmology Hospital, PARIS group, 28 rue de Charenton, 75712, Paris, France
| | - Elena Gofas-Salas
- Vision Institute and Quinze Vingts National Ophthalmology Hospital, PARIS group, 28 rue de Charenton, 75712, Paris, France
- DOTA, ONERA, Université Paris Saclay F-91123 Palaisea, France
| | | | - José Alain Sahel
- Vision Institute and Quinze Vingts National Ophthalmology Hospital, PARIS group, 28 rue de Charenton, 75712, Paris, France
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Michel Paques
- Vision Institute and Quinze Vingts National Ophthalmology Hospital, PARIS group, 28 rue de Charenton, 75712, Paris, France
| | - Ethan A. Rossi
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15213, USA
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13
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Marcos S, Werner JS, Burns SA, Merigan WH, Artal P, Atchison DA, Hampson KM, Legras R, Lundstrom L, Yoon G, Carroll J, Choi SS, Doble N, Dubis AM, Dubra A, Elsner A, Jonnal R, Miller DT, Paques M, Smithson HE, Young LK, Zhang Y, Campbell M, Hunter J, Metha A, Palczewska G, Schallek J, Sincich LC. Vision science and adaptive optics, the state of the field. Vision Res 2017; 132:3-33. [PMID: 28212982 PMCID: PMC5437977 DOI: 10.1016/j.visres.2017.01.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 12/27/2022]
Abstract
Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Yuhua Zhang
- University of Alabama at Birmingham, Birmingham, USA
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14
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Schwarz C, Sharma R, Fischer WS, Chung M, Palczewska G, Palczewski K, Williams DR, Hunter JJ. Safety assessment in macaques of light exposures for functional two-photon ophthalmoscopy in humans. BIOMEDICAL OPTICS EXPRESS 2016; 7:5148-5169. [PMID: 28018732 PMCID: PMC5175559 DOI: 10.1364/boe.7.005148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/08/2016] [Accepted: 11/09/2016] [Indexed: 05/18/2023]
Abstract
Two-photon ophthalmoscopy has potential for in vivo assessment of function of normal and diseased retina. However, light safety of the sub-100 fs laser typically used is a major concern and safety standards are not well established. To test the feasibility of safe in vivo two-photon excitation fluorescence (TPEF) imaging of photoreceptors in humans, we examined the effects of ultrashort pulsed light and the required light levels with a variety of clinical and high resolution imaging methods in macaques. The only measure that revealed a significant effect due to exposure to pulsed light within existing safety standards was infrared autofluorescence (IRAF) intensity. No other structural or functional alterations were detected by other imaging techniques for any of the exposures. Photoreceptors and retinal pigment epithelium appeared normal in adaptive optics images. No effect of repeated exposures on TPEF time course was detected, suggesting that visual cycle function was maintained. If IRAF reduction is hazardous, it is the only hurdle to applying two-photon retinal imaging in humans. To date, no harmful effects of IRAF reduction have been detected.
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Affiliation(s)
- Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Robin Sharma
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | | | - Mina Chung
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
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15
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Alexander NS, Palczewska G, Stremplewski P, Wojtkowski M, Kern TS, Palczewski K. Image registration and averaging of low laser power two-photon fluorescence images of mouse retina. BIOMEDICAL OPTICS EXPRESS 2016; 7:2671-91. [PMID: 27446697 PMCID: PMC4948621 DOI: 10.1364/boe.7.002671] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/11/2016] [Accepted: 06/11/2016] [Indexed: 05/18/2023]
Abstract
Two-photon fluorescence microscopy (TPM) is now being used routinely to image live cells for extended periods deep within tissues, including the retina and other structures within the eye . However, very low laser power is a requirement to obtain TPM images of the retina safely. Unfortunately, a reduction in laser power also reduces the signal-to-noise ratio of collected images, making it difficult to visualize structural details. Here, image registration and averaging methods applied to TPM images of the eye in living animals (without the need for auxiliary hardware) demonstrate the structural information obtained with laser power down to 1 mW. Image registration provided between 1.4% and 13.0% improvement in image quality compared to averaging images without registrations when using a high-fluorescence template, and between 0.2% and 12.0% when employing the average of collected images as the template. Also, a diminishing return on image quality when more images were used to obtain the averaged image is shown. This work provides a foundation for obtaining informative TPM images with laser powers of 1 mW, compared to previous levels for imaging mice ranging between 6.3 mW [Palczewska G., Nat Med.20, 785 (2014) Sharma R., Biomed. Opt. Express4, 1285 (2013)].
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Affiliation(s)
- Nathan S Alexander
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
| | | | - Patrycjusz Stremplewski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Maciej Wojtkowski
- Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, 87-100 Torun, Poland
| | - Timothy S Kern
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; Polgenix Inc., 11000 Cedar Ave, Cleveland, Ohio 44106, USA;
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16
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Merino D, Loza-Alvarez P. Adaptive optics scanning laser ophthalmoscope imaging: technology update. Clin Ophthalmol 2016; 10:743-55. [PMID: 27175057 PMCID: PMC4854423 DOI: 10.2147/opth.s64458] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it.
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Affiliation(s)
- David Merino
- The Institute of Photonic Sciences (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Pablo Loza-Alvarez
- The Institute of Photonic Sciences (ICFO), The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
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17
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van Norren D, Vos JJ. Light damage to the retina: an historical approach. Eye (Lond) 2016; 30:169-72. [PMID: 26541088 PMCID: PMC4763118 DOI: 10.1038/eye.2015.218] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 09/20/2015] [Indexed: 12/14/2022] Open
Abstract
A brief review of retinal light damage is presented. Thermal damage requires a local rise in temperature of at least 10 °C, causing an instant denaturation of proteins. The primary absorber is melanin. Photochemical damage occurs at body temperature and involves cellular damage by reactive forms of oxygen. The photosensitizers are photoproducts of the visual pigments. First indications that non-thermal damage might exist, in particular in the case of eclipse blindness, was presented by Vos in 1962. Attribution thereof to photochemical action was presented in 1966 by Noell et al who also measured the first action spectrum, in rat. It turned out to be identical to the absorption spectrum of rhodopsin. However, in 1976 and 1982 Ham et al found a quite different spectrum in monkeys, peaking at short wavelengths. The latter spectrum, but not the former, was confirmed since in numerous publications with animal models including rat. In ophthalmological practice a 'sunburn' was at first the only complaint caused by light damage. To avoid this, patients with dilated pupils should always be advised to wear sunglasses. Since the invention of the laser accidents have been reported, the most recent development is youth playfully pointing a strong laser pen in their eyes with marked consequences. The operation microscope and endoilluminators should always be used as brief as possible to avoid photochemical damage. Arguments for implant lenses that block not only the UV but also part of the visible spectrum seem too weak to justify extra costs.
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Affiliation(s)
- D van Norren
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands
- TNO Soesterberg, Soesterberg, The Netherlands
| | - J J Vos
- TNO Soesterberg, Soesterberg, The Netherlands
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18
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Cideciyan AV, Swider M, Jacobson SG. Autofluorescence imaging with near-infrared excitation:normalization by reflectance to reduce signal from choroidal fluorophores. Invest Ophthalmol Vis Sci 2015; 56:3393-406. [PMID: 26024124 DOI: 10.1167/iovs.15-16726] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. METHODS Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. RESULTS Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizing NIR-RAFI reduced the choroidal component of the signal in regions of atrophy. Quantitative evaluation of RPE atrophy area showed no significant differences between SW-RAFI and normalized NIR-RAFI. CONCLUSIONS Imaging of RPE atrophy using lipofuscin-based AF imaging has become the gold standard. However, this technique involves bright SW lights that are uncomfortable and may accelerate the rate of disease progression in vulnerable retinas. The NIR-RAFI method developed here is a melanin-based alternative that is not absorbed by opsins and bisretinoid moieties, and is comfortable to view. Further development of this method may result in a nonmydriatic and comfortable imaging method to quantify RPE atrophy extent and its expansion rate.
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