1
|
Baez HC, LaPorta JM, Walker AD, Fischer WS, Hollar R, Patterson S, DiLoreto DA, Gullapalli V, McGregor JE. Inner limiting Membrane Peel Extends In vivo Calcium Imaging of Retinal Ganglion Cell Activity Beyond the Fovea in Non-Human Primate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.02.597041. [PMID: 38854047 PMCID: PMC11160754 DOI: 10.1101/2024.06.02.597041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
High resolution retinal imaging paired with intravitreal injection of a viral vector coding for the calcium indicator GCaMP has enabled visualization of activity dependent calcium changes in retinal ganglion cells (RGCs) at single cell resolution in the living eye. The inner limiting membrane (ILM) is a barrier for viral vectors, restricting transduction to a ring of RGCs serving the fovea in both humans and non-human primates (NHP). We evaluate peeling the ILM prior to intravitreal injection as a strategy to expand calcium imaging beyond the fovea in the NHP eye in vivo. Five Macaca fascicularis eyes (age 3-10y; n=3 individuals; 2M, 1F) underwent vitrectomy and 5 to 6-disc diameter ILM peel centered on the fovea prior to intravitreal delivery of 7m8:SNCG:GCaMP8s. Calcium responses from RGCs were recorded using a fluorescence adaptive optics scanning laser ophthalmoscope. In all eyes GCaMP was expressed throughout the peeled area, representing a mean 8-fold enlargement in area of expression relative to a control eye. Calcium recordings were obtained up to 11 degrees from the foveal center. RGC responses were comparable to the fellow control eye and showed no significant decrease over the 6 months post ILM peel, suggesting that RGC function was not compromised by the surgical procedure. In addition, we demonstrate that activity can be recorded directly from the retinal nerve fiber layer. This approach will be valuable for a range of applications in visual neuroscience including pre-clinical evaluation of retinal function, detecting vision loss, and assessing the impact of therapeutic interventions.
Collapse
Affiliation(s)
- Hector C Baez
- Department of Biomedical Engineering, University of Rochester, Rochester, NY
- Center for Visual Science, University of Rochester, Rochester, NY
| | | | - Amber D Walker
- Center for Visual Science, University of Rochester, Rochester, NY
| | | | - Rachel Hollar
- Center for Visual Science, University of Rochester, Rochester, NY
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY
| | - Sara Patterson
- Center for Visual Science, University of Rochester, Rochester, NY
| | - David A DiLoreto
- Center for Visual Science, University of Rochester, Rochester, NY
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY
| | - Vamsi Gullapalli
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY
| | - Juliette E McGregor
- Center for Visual Science, University of Rochester, Rochester, NY
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY
| |
Collapse
|
2
|
Godat T, Kohout K, Yang Q, Parkins K, McGregor JE, Merigan WH, Williams DR, Patterson SS. Cone-Opponent Ganglion Cells in the Primate Fovea Tuned to Non-Cardinal Color Directions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.15.557995. [PMID: 37745616 PMCID: PMC10516013 DOI: 10.1101/2023.09.15.557995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
A long-standing question in vision science is how the three cone photoreceptor types - long (L), medium (M) and short (S) wavelength sensitive - combine to generate our perception of color. Hue perception can be described along two opponent axes: red-green and blue-yellow. Psychophysical measurements of color appearance indicate that the cone inputs to the red-green and blue-yellow opponent axes are M vs. L+S and L vs. M+S, respectively. However, the "cardinal directions of color space" revealed by psychophysical measurements of color detection thresholds are L vs. M and S vs. L+M. The cardinal directions match the most common cone-opponent retinal ganglion cells (RGCs) in the primate retina. Accordingly, the cone opponency necessary for color appearance is thought to be established in cortex. However, small populations with the appropriate M vs. L+S and L vs. M+S cone-opponency have been reported in large surveys of cone inputs to primate RGCs and their projections to the lateral geniculate nucleus (LGN) yet their existence continues to be debated. Resolving this long-standing open question is needed as a complete account of the cone-opponency in the retinal output is critical for efforts to understand how downstream neural circuits process color. Here, we performed adaptive optics calcium imaging to longitudinally and noninvasively measurements of the foveal RGC light responses in the living macaque eye. We confirm the presence of L vs. M+S and M vs. L+S neurons with non-cardinal cone-opponency and demonstrate that cone-opponent signals in the retinal output are substantially more diverse than classically thought.
Collapse
Affiliation(s)
- Tyler Godat
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
- Institute of Optics, University of Rochester, Rochester, NY, 14627
| | - Kendall Kohout
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
| | - Qiang Yang
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
| | - Keith Parkins
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
| | - Juliette E. McGregor
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, 14642
| | - William H. Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, 14642
| | - David R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
- Institute of Optics, University of Rochester, Rochester, NY, 14627
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, 14642
| | - Sara S. Patterson
- Center for Visual Science, University of Rochester, Rochester, NY, 14607
| |
Collapse
|
3
|
Sabesan R, Grieve K, Hammer DX, Ji N, Marcos S. Introduction to the Feature Issue on Adaptive Optics for Biomedical Applications. BIOMEDICAL OPTICS EXPRESS 2023; 14:1772-1776. [PMID: 37078031 PMCID: PMC10110319 DOI: 10.1364/boe.488044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Indexed: 05/03/2023]
Abstract
The guest editors introduce a feature issue commemorating the 25th anniversary of adaptive optics in biomedical research.
Collapse
Affiliation(s)
- Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Kate Grieve
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, and CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, F-75012 Paris, France
| | - Daniel X. Hammer
- Center for Devices and Radiological Health (CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, MD 20993, USA
| | - Na Ji
- Department of Physics, Department of Molecular & Cellular Biology, University of California, Berkeley, CA 94720, USA
| | - Susana Marcos
- Visual Optics and Biophotonics Laboratory, Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Calle Serrano 121, Madrid, 28006, Spain
- Center for Visual Sciences; The Institute of Optics and Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
| |
Collapse
|
4
|
Williams DR, Burns SA, Miller DT, Roorda A. Evolution of adaptive optics retinal imaging [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:1307-1338. [PMID: 36950228 PMCID: PMC10026580 DOI: 10.1364/boe.485371] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 02/02/2023] [Indexed: 05/02/2023]
Abstract
This review describes the progress that has been achieved since adaptive optics (AO) was incorporated into the ophthalmoscope a quarter of a century ago, transforming our ability to image the retina at a cellular spatial scale inside the living eye. The review starts with a comprehensive tabulation of AO papers in the field and then describes the technological advances that have occurred, notably through combining AO with other imaging modalities including confocal, fluorescence, phase contrast, and optical coherence tomography. These advances have made possible many scientific discoveries from the first maps of the topography of the trichromatic cone mosaic to exquisitely sensitive measures of optical and structural changes in photoreceptors in response to light. The future evolution of this technology is poised to offer an increasing array of tools to measure and monitor in vivo retinal structure and function with improved resolution and control.
Collapse
Affiliation(s)
- David R. Williams
- The Institute of Optics and the Center for
Visual Science, University of Rochester,
Rochester NY, USA
| | - Stephen A. Burns
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Donald T. Miller
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and
Vision Science, University of California at Berkeley, Berkeley CA, USA
| |
Collapse
|
5
|
In vivo chromatic and spatial tuning of foveolar retinal ganglion cells in Macaca fascicularis. PLoS One 2022; 17:e0278261. [PMID: 36445926 PMCID: PMC9707781 DOI: 10.1371/journal.pone.0278261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 11/13/2022] [Indexed: 11/30/2022] Open
Abstract
The primate fovea is specialized for high acuity chromatic vision, with the highest density of cone photoreceptors and a disproportionately large representation in visual cortex. The unique visual properties conferred by the fovea are conveyed to the brain by retinal ganglion cells, the somas of which lie at the margin of the foveal pit. Microelectrode recordings of these centermost retinal ganglion cells have been challenging due to the fragility of the fovea in the excised retina. Here we overcome this challenge by combining high resolution fluorescence adaptive optics ophthalmoscopy with calcium imaging to optically record functional responses of foveal retinal ganglion cells in the living eye. We use this approach to study the chromatic responses and spatial transfer functions of retinal ganglion cells using spatially uniform fields modulated in different directions in color space and monochromatic drifting gratings. We recorded from over 350 cells across three Macaca fascicularis primates over a time period of weeks to months. We find that the majority of the L vs. M cone opponent cells serving the most central foveolar cones have spatial transfer functions that peak at high spatial frequencies (20-40 c/deg), reflecting strong surround inhibition that sacrifices sensitivity at low spatial frequencies but preserves the transmission of fine detail in the retinal image. In addition, we fit to the drifting grating data a detailed model of how ganglion cell responses draw on the cone mosaic to derive receptive field properties of L vs. M cone opponent cells at the very center of the foveola. The fits are consistent with the hypothesis that foveal midget ganglion cells are specialized to preserve information at the resolution of the cone mosaic. By characterizing the functional properties of retinal ganglion cells in vivo through adaptive optics, we characterize the response characteristics of these cells in situ.
Collapse
|
6
|
Nanjappa R, Dilbeck MD, Economides JR, Horton JC. Fundus imaging of retinal ganglion cells transduced by retrograde transport of rAAV2-retro. Exp Eye Res 2022; 219:109084. [PMID: 35460667 DOI: 10.1016/j.exer.2022.109084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/07/2022] [Accepted: 04/13/2022] [Indexed: 11/18/2022]
Abstract
Access of adeno-associated virus (AAV) to ganglion cells following intravitreal injection for gene therapy is impeded by the internal limiting membrane of the retina. As an alternative, one could transduce ganglion cells via retrograde transport after virus injection into a retinal target nucleus. It is unknown if recombinant AAV2-retro (rAAV2-retro), a variant of AAV2 developed specifically for retrograde transport, is capable of transducing retinal ganglion cells. To address this issue, equal volumes of rAAV2-retro-hSyn-EGFP and rAAV2-retro-hSyn-mCherry were mixed in a micropipette and injected into the rat superior colliculus. The time-course of viral transduction was tracked by performing serial in vivo fundus imaging. Cells that were labeled by the fluorophores within the first week remained consistent in distribution and relative signal strength on follow-up imaging. Most transduced cells were double-labeled, but some were labeled by only EGFP or mCherry. Fundus images were later aligned with retinal wholemounts. Ganglion cells in the wholemounts matched precisely the cells imaged by fundus photography. As seen in the fundus images, ganglion cells in wholemounts were sometimes labeled by only EGFP or mCherry. Overall, there was detectable label in 32-41% of ganglion cells. Analysis of the number of cells labeled by 0, 1, or 2 fluorophores, based on Poisson statistics, yielded an average of 0.66 virions transducing each ganglion cell. Although this represents a low number relative to the quantity of virus injected into the superior colliculus, the ganglion cells showed sustained and robust fluorescent labeling. In the primate, injection of rAAV2-retro into the lateral geniculate nucleus might provide a viable approach for the transduction of ganglion cells, bypassing the obstacles that have prevented effective gene delivery via intravitreal injection.
Collapse
Affiliation(s)
- Rakesh Nanjappa
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Mikayla D Dilbeck
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - John R Economides
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Jonathan C Horton
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, 94143, USA.
| |
Collapse
|
7
|
Tools and Biomarkers for the Study of Retinal Ganglion Cell Degeneration. Int J Mol Sci 2022; 23:ijms23084287. [PMID: 35457104 PMCID: PMC9025234 DOI: 10.3390/ijms23084287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/03/2022] [Accepted: 04/08/2022] [Indexed: 11/17/2022] Open
Abstract
The retina is part of the central nervous system, its analysis may provide an idea of the health and functionality, not only of the retina, but also of the entire central nervous system, as has been shown in Alzheimer’s or Parkinson’s diseases. Within the retina, the ganglion cells (RGC) are the neurons in charge of processing and sending light information to higher brain centers. Diverse insults and pathological states cause degeneration of RGC, leading to irreversible blindness or impaired vision. RGCs are the measurable endpoints in current research into experimental therapies and diagnosis in multiple ocular pathologies, like glaucoma. RGC subtype classifications are based on morphological, functional, genetical, and immunohistochemical aspects. Although great efforts are being made, there is still no classification accepted by consensus. Moreover, it has been observed that each RGC subtype has a different susceptibility to injury. Characterizing these subtypes together with cell death pathway identification will help to understand the degenerative process in the different injury and pathological models, and therefore prevent it. Here we review the known RGC subtypes, as well as the diagnostic techniques, probes, and biomarkers for programmed and unprogrammed cell death in RGC.
Collapse
|
8
|
Schock F, Best G, Celik N, Heintzmann R, Dithmar S, Cremer C. Structured illumination ophthalmoscope: super-resolution microscopy on the living human eye. PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A: MATHEMATICAL, PHYSICAL AND ENGINEERING SCIENCES 2022; 380:20210151. [PMID: 0 DOI: 10.1098/rsta.2021.0151] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 01/15/2022] [Indexed: 05/19/2023]
Abstract
In this paper, we present the prototype of an ophthalmoscope that uses structured illumination microscopy (SIM) to enable super-resolved imaging of the human retina, and give first insights into clinical application possibilities. The SIM technique was applied to build a prototype that uses the lens of the human eye as an objective to ‘super-resolve’ the retina of a living human. In our multidisciplinary collaboration, we have adapted this well-established technique in ophthalmology and successfully imaged a human retina using significantly lower light intensity than a state-of-the-art ophthalmoscope. Here, we focus on the technical implementation and highlight future perspectives of this method. A more application-oriented note for physicians on the diagnostic and disease-preventive value of this method, as well as the medical results of the clinical study carried out, will be published in a report addressed to an appropriate specialist audience.
This article is part of the Theo Murphy meeting issue ‘Super-resolution structured illumination microscopy (part 2)’.
Collapse
Affiliation(s)
- Florian Schock
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
- Kirchhoff-Institute for Physics, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Institute of Pharmacy and Molecular Biotechnology, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
| | - Gerrit Best
- Kirchhoff-Institute for Physics, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Institute of Pharmacy and Molecular Biotechnology, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany
| | - Nil Celik
- Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany
| | - Rainer Heintzmann
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Jena, Germany
- Leibniz Institute of Photonic Technology, Jena, Germany
| | - Stefan Dithmar
- Department of Ophthalmology, HELIOS-HSK, Wiesbaden, Germany
- Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany
| | - Christoph Cremer
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
- Kirchhoff-Institute for Physics, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Institute of Pharmacy and Molecular Biotechnology, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
- Max Planck Institute for Polymer Research, Mainz, Germany
| |
Collapse
|
9
|
Joseph A, Power D, Schallek J. Imaging the dynamics of individual processes of microglia in the living retina in vivo. BIOMEDICAL OPTICS EXPRESS 2021; 12:6157-6183. [PMID: 34745728 PMCID: PMC8547988 DOI: 10.1364/boe.426157] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/29/2021] [Accepted: 08/29/2021] [Indexed: 05/18/2023]
Abstract
Microglia are an essential population of resident immune cells in the central nervous system (CNS) and retina. These microscopic cells possess sub-cellular processes that make them challenging to image due to limited resolution and contrast. The baseline behavior of microglial processes in the living retina has been poorly characterized, and yet are essential to understanding how these cells respond under conditions of health, development, stress and disease. Here we use in vivo adaptive optics scanning light ophthalmoscopy combined with time-lapse imaging and quantification of process motility, to reveal the detailed behavior of microglial cells in a population of healthy mice. We find microglial processes to be dynamic at all branch-levels, from primary to end-protrusions. Cell-processes remodel at average speeds of 0.6 ± 0.4 µm/min with growth and deletion bursts of 0-7.6 µm/min. Longitudinal imaging in the same mice showed cell-somas to remain stable over seconds to minutes, but show migration over days to months. In addition to characterizing in vivo process motility and Sholl analysis using a microglial reporter mouse, we also demonstrate that microglia can be imaged without fluorescent labels at all. Phase-contrast imaging using safe levels of near-infrared light successfully imaged microglia soma and process remodeling with micron-level detail noninvasively, confirmed by simultaneous imaging of fluorescent microglial cells in transgenic mice. This label-free approach provides a new opportunity to investigate CNS immune system noninvasively without requiring transgenic or antibody labeling which could have off-target effects of changing normal microglial behavior. Additionally, CNS microglia study can now be conducted without the need for cranial window surgery which have the potential to change their behavior due to local or systemic inflammation.
Collapse
Affiliation(s)
- Aby Joseph
- The Institute of Optics, University of Rochester, Rochester, NY 14620, USA
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Derek Power
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
| | - Jesse Schallek
- Center for Visual Science, University of Rochester, Rochester, NY 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA
| |
Collapse
|
10
|
Ringel MJ, Tang EM, Tao YK. Advances in multimodal imaging in ophthalmology. Ther Adv Ophthalmol 2021; 13:25158414211002400. [PMID: 35187398 PMCID: PMC8855415 DOI: 10.1177/25158414211002400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
Multimodality ophthalmic imaging systems aim to enhance the contrast, resolution, and functionality of existing technologies to improve disease diagnostics and therapeutic guidance. These systems include advanced acquisition and post-processing methods using optical coherence tomography (OCT), combined scanning laser ophthalmoscopy and OCT systems, adaptive optics, surgical guidance, and photoacoustic technologies. Here, we provide an overview of these ophthalmic imaging systems and their clinical and basic science applications.
Collapse
Affiliation(s)
- Morgan J. Ringel
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Eric M. Tang
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Yuankai K. Tao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| |
Collapse
|
11
|
Rehman AU, Qureshi SA. A review of the medical hyperspectral imaging systems and unmixing algorithms' in biological tissues. Photodiagnosis Photodyn Ther 2020; 33:102165. [PMID: 33383204 DOI: 10.1016/j.pdpdt.2020.102165] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 01/27/2023]
Abstract
Hyperspectral fluorescence imaging (HFI) is a well-known technique in the medical research field and is considered a non-invasive tool for tissue diagnosis. This review article gives a brief introduction to acquisition methods, including the image preprocessing methods, feature selection and extraction methods, data classification techniques and medical image analysis along with recent relevant references. The process of fusion of unsupervised unmixing techniques with other classification methods, like the combination of support vector machine with an artificial neural network, the latest snapshot Hyperspectral imaging (HSI) and vortex analysis techniques are also outlined. Finally, the recent applications of hyperspectral images in cellular differentiation of various types of cancer are discussed.
Collapse
Affiliation(s)
- Aziz Ul Rehman
- Agri & Biophotonics Division, National Institute of Lasers and Optronics College, PIEAS, 45650, Islamabad, Pakistan; Department of Physics and Astronomy Macquarie University, Sydney, 2109, New South Wales, Australia.
| | - Shahzad Ahmad Qureshi
- Department of Computer and Information Sciences, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, 45650, Pakistan
| |
Collapse
|
12
|
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.
Collapse
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.
| |
Collapse
|
13
|
Aboualizadeh E, Phillips MJ, McGregor JE, DiLoreto DA, Strazzeri JM, Dhakal KR, Bateman B, Jager LD, Nilles KL, Stuedemann SA, Ludwig AL, Hunter JJ, Merigan WH, Gamm DM, Williams DR. Imaging Transplanted Photoreceptors in Living Nonhuman Primates with Single-Cell Resolution. Stem Cell Reports 2020; 15:482-497. [PMID: 32707075 PMCID: PMC7419740 DOI: 10.1016/j.stemcr.2020.06.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022] Open
Abstract
Stem cell-based transplantation therapies offer hope for currently untreatable retinal degenerations; however, preclinical progress has been largely confined to rodent models. Here, we describe an experimental platform for accelerating photoreceptor replacement therapy in the nonhuman primate, which has a visual system much more similar to the human. We deployed fluorescence adaptive optics scanning light ophthalmoscopy (FAOSLO) to noninvasively track transplanted photoreceptor precursors over time at cellular resolution in the living macaque. Fluorescently labeled photoreceptors generated from a CRX+/tdTomato human embryonic stem cell (hESC) reporter line were delivered subretinally to macaques with normal retinas and following selective ablation of host photoreceptors using an ultrafast laser. The fluorescent reporter together with FAOSLO allowed transplanted photoreceptor precursor survival, migration, and neurite formation to be monitored over time in vivo. Histological examination suggested migration of photoreceptor precursors to the outer plexiform layer and potential synapse formation in ablated areas in the macaque eye.
Collapse
Affiliation(s)
| | - M Joseph Phillips
- Waisman Center, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA
| | | | - David A DiLoreto
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Jennifer M Strazzeri
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Kamal R Dhakal
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Brittany Bateman
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | | | - Kelsy L Nilles
- Waisman Center, University of Wisconsin, Madison, WI, USA
| | | | | | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA; The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - William H Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, USA; Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - David M Gamm
- Waisman Center, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA; The Institute of Optics, University of Rochester, Rochester, NY, USA.
| |
Collapse
|
14
|
Vienola KV, Zhang M, Snyder VC, Sahel JA, Dansingani KK, Rossi EA. Microstructure of the retinal pigment epithelium near-infrared autofluorescence in healthy young eyes and in patients with AMD. Sci Rep 2020; 10:9561. [PMID: 32533046 PMCID: PMC7293312 DOI: 10.1038/s41598-020-66581-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 05/21/2020] [Indexed: 01/18/2023] Open
Abstract
Retinal pigmented epithelial (RPE) cells are essential for maintaining normal visual function, especially in their role in the visual cycle, and are thought to be one of the first cell classes affected by age-related macular degeneration (AMD). Clinical imaging systems routinely evaluate the structure of the RPE at the tissue level, but cellular level information may provide valuable RPE biomarkers of health, aging and disease. In this exploratory study, participants were imaged with 795 nm excitation in adaptive optics scanning laser ophthalmoscopy (AOSLO) to observe the microstructure of the near-infrared autofluorescence (AO-IRAF) from the RPE layer in healthy retinas and patients with AMD. The expected hexagonal mosaic of RPE cells was only sometimes seen in normal eyes, while AMD patients exhibited highly variable patterns of altered AO-IRAF. In some participants, AO-IRAF structure corresponding to cones was observed, as we have demonstrated previously. In some AMD patients, marked alterations in the pattern of AO-IRAF could be seen even in areas where the RPE appeared relatively normal in clinical imaging modalities, such as spectral domain optical coherence tomography (SD-OCT). AO-IRAF imaging using AOSLO offers promise for better detection and understanding of early RPE changes in the course of AMD, potentially before clinical signs appear.
Collapse
Affiliation(s)
- Kari V Vienola
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
| | - Min Zhang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Valerie C Snyder
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Kunal K Dansingani
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - 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
| |
Collapse
|
15
|
Qin Z, He S, Yang C, Yung JSY, Chen C, Leung CKS, Liu K, Qu JY. Adaptive optics two-photon microscopy enables near-diffraction-limited and functional retinal imaging in vivo. LIGHT, SCIENCE & APPLICATIONS 2020; 9:79. [PMID: 32411364 PMCID: PMC7203252 DOI: 10.1038/s41377-020-0317-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/11/2020] [Accepted: 04/15/2020] [Indexed: 05/08/2023]
Abstract
In vivo fundus imaging offers non-invasive access to neuron structures and biochemical processes in the retina. However, optical aberrations of the eye degrade the imaging resolution and prevent visualization of subcellular retinal structures. We developed an adaptive optics two-photon excitation fluorescence microscopy (AO-TPEFM) system to correct ocular aberrations based on a nonlinear fluorescent guide star and achieved subcellular resolution for in vivo fluorescence imaging of the mouse retina. With accurate wavefront sensing and rapid aberration correction, AO-TPEFM permits structural and functional imaging of the mouse retina with submicron resolution. Specifically, simultaneous functional calcium imaging of neuronal somas and dendrites was demonstrated. Moreover, the time-lapse morphological alteration and dynamics of microglia were characterized in a mouse model of retinal disorder. In addition, precise laser axotomy was achieved, and degeneration of retinal nerve fibres was studied. This high-resolution AO-TPEFM is a promising tool for non-invasive retinal imaging and can facilitate the understanding of a variety of eye diseases as well as neurodegenerative disorders in the central nervous system.
Collapse
Affiliation(s)
- Zhongya Qin
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Sicong He
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Chao Yang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jasmine Sum-Yee Yung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Congping Chen
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | | | - Kai Liu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianan Y. Qu
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| |
Collapse
|
16
|
Blasinski H, Farrell J, Wandell B. Simultaneous Surface Reflectance and Fluorescence Spectra Estimation. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2020; 29:8791-8804. [PMID: 32112682 DOI: 10.1109/tip.2020.2973810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
There is widespread interest in estimating the fluorescence properties of natural materials in an image. However, the separation between reflected and fluoresced components is difficult, because it is impossible to distinguish reflected and fluoresced photons without controlling the illuminant spectrum. We show how to jointly estimate the reflectance and fluorescence from a single set of images acquired under multiple illuminants. We present a framework based on a linear approximation to the physical equations describing image formation in terms of surface spectral reflectance and fluorescence due to multiple fluorophores. We relax the non-convex, inverse estimation problem in order to jointly estimate the reflectance and fluorescence properties in a single optimization step. We provide a software implementation of the solver for our method and prior methods. We evaluate the accuracy and reliability of the method using both simulations and experimental data. To evaluate the methods experimentally we built a custom imaging system using a monochrome camera, a filter wheel with bandpass transmissive filters and a small number of light emitting diodes. We compared the methods based upon our framework with the ground truth as well as with prior methods.
Collapse
|
17
|
Lakkaraju A, Umapathy A, Tan LX, Daniele L, Philp NJ, Boesze-Battaglia K, Williams DS. The cell biology of the retinal pigment epithelium. Prog Retin Eye Res 2020; 78:100846. [PMID: 32105772 PMCID: PMC8941496 DOI: 10.1016/j.preteyeres.2020.100846] [Citation(s) in RCA: 185] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023]
Abstract
The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically situated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and function. Dysfunction of the RPE underlies many inherited and acquired diseases that cause permanent blindness. Decades of research have yielded valuable insight into the cell biology of the RPE. In recent years, new technologies such as live-cell imaging have resulted in major advancement in our understanding of areas such as the daily phagocytosis and clearance of photoreceptor outer segment tips, autophagy, endolysosome function, and the metabolic interplay between the RPE and photoreceptors. In this review, we aim to integrate these studies with an emphasis on appropriate models and techniques to investigate RPE cell biology and metabolism, and discuss how RPE cell biology informs our understanding of retinal disease.
Collapse
Affiliation(s)
- Aparna Lakkaraju
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Ankita Umapathy
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Li Xuan Tan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Lauren Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| |
Collapse
|
18
|
Liu F, Lin C, Hong J, Cai C, Zhang W, Zhang J, Guo L. Apocynin protects retina cells from ultraviolet radiation damage via inducing sirtuin 1. J Drug Target 2019; 28:330-338. [PMID: 31479288 DOI: 10.1080/1061186x.2019.1663527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Direct exposure to Ultraviolet (UV) radiation causes progressive damages in retinal cells, which is one of the hypothetical mechanisms underlying age-related retinopathy or macular degeneration. The protective effects of Apocynin against UV damages were firstly tested in retinal pigment epithelium cells (RPEs) and retinal ganglion cells (RGCs). Subsequently the beneficial effect of Apocynin on mouse retinas against light damage were examined. Next, microarray profiling was used to identify the genes regulated by Apocynin in both RPEs and RGCs. A candidate gene was isolated for functional characterisation by knock-down study. Apocynin was shown to inhibit cell death, reduce oxidative stress and deoxyribonucleic acid damages in both RPEs and RGCs challenged with UV. Intravitreal application of Apocynin also improved retinal dysfunction caused by light damage. Sirtuin 1 (SIRT1) was identified as induced by Apocynin by microarray study. The induction was confirmed by realtime-PCR and western blotting. Knocking down SIRT1 antagonised the protective effect of Apocynin against UV damages in both RPEs and RGCs. Apocynin is a novel agent that shows both in vitro and in vivo efficacies against UV radiation induced retina damages. SIRT1 pathway is implicated in UV radiation protection of Apocynin in retinal cells.
Collapse
Affiliation(s)
- Feng Liu
- Department of Radiation Oncology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Chen Lin
- Department of Ophthalmology, Shenzhen Aier Eye Hospital, Shenzhen, China
| | - Jinsheng Hong
- Department of Radiation Oncology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Chuanshu Cai
- Department of Radiation Oncology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Weijian Zhang
- Department of Radiation Oncology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Jianrong Zhang
- Department of Anesthesiology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Lihong Guo
- Department of Radiation Oncology, The First Affiliated Hospital of Fujian Medical University, Fujian, China
| |
Collapse
|
19
|
Jiang X, Kuchenbecker JA, Touch P, Sabesan R. Measuring and compensating for ocular longitudinal chromatic aberration. OPTICA 2019; 6:981-990. [PMID: 33614858 PMCID: PMC7894623 DOI: 10.1364/optica.6.000981] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/15/2019] [Indexed: 05/18/2023]
Abstract
It is well known that the eye's optics and media introduce monochromatic and chromatic aberration unique to each individual. Once monochromatic aberrations are removed with adaptive optics (AO), longitudinal chromatic aberrations (LCA) define the fidelity for multi-wavelength, high-resolution vision testing and retinal imaging. AO vision simulation systems and AO scanning laser ophthalmoscopes (AOSLOs) typically use the average population LCA to compensate for focus offsets between different wavelengths precluding fine, individualized control. The eye's LCA has been characterized extensively using either subjective (visual perception) or objective (imaging) methods. Classically, these have faced inconsistencies due to extraneous factors related to depth of focus, monochromatic aberration, and wavelength-dependent light interactions with retinal tissue. Here, we introduce a filter-based Badal LCA compensator that offers the flexibility to tune LCA for each individual eye and demonstrate its feasibility for vision testing and imaging using multiple wavelengths simultaneously. Incorporating the LCA compensator in an AOSLO allowed the first objective measurements of LCA based on confocal, multi-wavelength foveal cone images and its comparison to measures obtained subjectively. The objective LCA thus obtained was consistent with subjective estimates in the same individuals and hence resolves the prior discrepancies between them. Overall, the described approach will benefit applications in retinal imaging and vision testing where the focus of multiple wavelengths needs to be controlled independently and simultaneously.
Collapse
|
20
|
Cunefare D, Huckenpahler AL, Patterson EJ, Dubra A, Carroll J, Farsiu S. RAC-CNN: multimodal deep learning based automatic detection and classification of rod and cone photoreceptors in adaptive optics scanning light ophthalmoscope images. BIOMEDICAL OPTICS EXPRESS 2019; 10:3815-3832. [PMID: 31452977 PMCID: PMC6701534 DOI: 10.1364/boe.10.003815] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/26/2019] [Accepted: 06/29/2019] [Indexed: 05/03/2023]
Abstract
Quantification of the human rod and cone photoreceptor mosaic in adaptive optics scanning light ophthalmoscope (AOSLO) images is useful for the study of various retinal pathologies. Subjective and time-consuming manual grading has remained the gold standard for evaluating these images, with no well validated automatic methods for detecting individual rods having been developed. We present a novel deep learning based automatic method, called the rod and cone CNN (RAC-CNN), for detecting and classifying rods and cones in multimodal AOSLO images. We test our method on images from healthy subjects as well as subjects with achromatopsia over a range of retinal eccentricities. We show that our method is on par with human grading for detecting rods and cones.
Collapse
Affiliation(s)
- David Cunefare
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Alison L. Huckenpahler
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Emily J. Patterson
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Stanford University, Palo Alto, CA 94303, USA
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
| |
Collapse
|
21
|
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.
Collapse
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
| |
Collapse
|
22
|
Burns SA, Elsner AE, Sapoznik KA, Warner RL, Gast TJ. Adaptive optics imaging of the human retina. Prog Retin Eye Res 2019; 68:1-30. [PMID: 30165239 PMCID: PMC6347528 DOI: 10.1016/j.preteyeres.2018.08.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/18/2022]
Abstract
Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.
Collapse
Affiliation(s)
- Stephen A Burns
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States.
| | - Ann E Elsner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kaitlyn A Sapoznik
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Raymond L Warner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Thomas J Gast
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| |
Collapse
|
23
|
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.
Collapse
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
| |
Collapse
|
24
|
Nafar Z, Wen R, Jiao S. Visible-light optical coherence tomography-based multimodal system for quantitative fundus autofluorescence imaging. Exp Biol Med (Maywood) 2018; 243:1265-1274. [PMID: 30472882 PMCID: PMC6348593 DOI: 10.1177/1535370218813529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
IMPACT STATEMENT Quantitative fundus autofluorescence imaging with simultaneous visible-light optical coherence tomography-based multimodal technology has potential significant impact on the diagnosis and monitoring the progression of retinal diseases.
Collapse
Affiliation(s)
- Zahra Nafar
- Department of Biomedical Engineering, Florida International
University, Miami, FL 33174, USA
| | - Rong Wen
- Bascom Palmer Eye Institute, University of Miami Miller School
of Medicine, Miami, FL 33136, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International
University, Miami, FL 33174, USA
| |
Collapse
|
25
|
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.
Collapse
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
| |
Collapse
|
26
|
Mahbub SB, Plöschner M, Gosnell ME, Anwer AG, Goldys EM. Statistically strong label-free quantitative identification of native fluorophores in a biological sample. Sci Rep 2017; 7:15792. [PMID: 29150629 PMCID: PMC5693869 DOI: 10.1038/s41598-017-15952-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/03/2017] [Indexed: 11/16/2022] Open
Abstract
Bioimaging using endogenous cell fluorescence, without any external biomarkers makes it possible to explore cells and tissues in their original native state, also in vivo. In order to be informative, this label-free method requires careful multispectral or hyperspectral recording of autofluorescence images followed by unsupervised extraction (unmixing) of biochemical signatures. The unmixing is difficult due to the scarcity of biochemically pure regions in cells and also because autofluorescence is weak compared with signals from labelled cells, typically leading to low signal to noise ratio. Here, we solve the problem of unsupervised hyperspectral unmixing of cellular autofluorescence by introducing the Robust Dependent Component Analysis (RoDECA). This approach provides sophisticated and statistically robust quantitative biochemical analysis of cellular autofluorescence images. We validate our method on artificial images, where the addition of varying known level of noise has allowed us to quantify the accuracy of our RoDECA analysis in a way that can be applied to real biological datasets. The same unsupervised statistical minimisation is then applied to imaging of mouse retinal photoreceptor cells where we establish the identity of key endogenous fluorophores (free NADH, FAD and lipofuscin) and derive the corresponding molecular abundance maps. The pre-processing methodology of image datasets is also presented, which is essential for the spectral unmixing analysis, but mostly overlooked in the previous studies.
Collapse
Affiliation(s)
- Saabah B Mahbub
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia.
| | - Martin Plöschner
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
| | - Martin E Gosnell
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
- Quantitative Pty Ltd, ABN 17165684186, 116-118 Great Western Highway, Mt. Victoria, NSW, 2786, Australia
| | - Ayad G Anwer
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
| | - Ewa M Goldys
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia.
| |
Collapse
|
27
|
Liu T, Jung H, Liu J, Droettboom M, Tam J. Noninvasive near infrared autofluorescence imaging of retinal pigment epithelial cells in the human retina using adaptive optics. BIOMEDICAL OPTICS EXPRESS 2017; 8:4348-4360. [PMID: 29082069 PMCID: PMC5654784 DOI: 10.1364/boe.8.004348] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/25/2017] [Accepted: 08/29/2017] [Indexed: 05/18/2023]
Abstract
The retinal pigment epithelial (RPE) cells contain intrinsic fluorophores that can be visualized using infrared autofluorescence (IRAF). Although IRAF is routinely utilized in the clinic for visualizing retinal health and disease, currently, it is not possible to discern cellular details using IRAF due to limits in resolution. We demonstrate that the combination of adaptive optics (AO) with IRAF (AO-IRAF) enables higher-resolution imaging of the IRAF signal, revealing the RPE mosaic in the living human eye. Quantitative analysis of visualized RPE cells in 10 healthy subjects across various eccentricities demonstrates the possibility for in vivo density measurements of RPE cells, which range from 6505 to 5388 cells/mm2 for the areas measured (peaking at the fovea). We also identified cone photoreceptors in relation to underlying RPE cells, and found that RPE cells support on average up to 18.74 cone photoreceptors in the fovea down to an average of 1.03 cone photoreceptors per RPE cell at an eccentricity of 6 mm. Clinical application of AO-IRAF to a patient with retinitis pigmentosa illustrates the potential for AO-IRAF imaging to become a valuable complementary approach to the current landscape of high resolution imaging modalities.
Collapse
Affiliation(s)
- Tao Liu
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - HaeWon Jung
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jianfei Liu
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Johnny Tam
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| |
Collapse
|
28
|
Chang YC, Walston ST, Chow RH, Weiland JD. GCaMP expression in retinal ganglion cells characterized using a low-cost fundus imaging system. J Neural Eng 2017; 14:056018. [PMID: 28930702 DOI: 10.1088/1741-2552/aa7ded] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Virus-transduced, intracellular-calcium indicators are effective reporters of neural activity, offering the advantage of cell-specific labeling. Due to the existence of an optimal time window for the expression of calcium indicators, a suitable tool for tracking GECI expression in vivo following transduction is highly desirable. APPROACH We developed a noninvasive imaging approach based on a custom-modified, low-cost fundus viewing system that allowed us to monitor and characterize in vivo bright-field and fluorescence images of the mouse retina. AAV2-CAG-GCaMP6f was injected into a mouse eye. The fundus imaging system was used to measure fluorescence at several time points post injection. At defined time points, we prepared wholemount retina mounted on a transparent multielectrode array and used calcium imaging to evaluate the responsiveness of retinal ganglion cells (RGCs) to external electrical stimulation. MAIN RESULTS The noninvasive fundus imaging system clearly resolves individual (RGCs and axons. RGC fluorescence intensity and the number of observable fluorescent cells show a similar rising trend from week 1 to week 3 after viral injection, indicating a consistent increase of GCaMP6f expression. Analysis of the in vivo fluorescence intensity trend and in vitro neurophysiological responsiveness shows that the slope of intensity versus days post injection can be used to estimate the optimal time for calcium imaging of RGCs in response to external electrical stimulation. SIGNIFICANCE The proposed fundus imaging system enables high-resolution digital fundus imaging in the mouse eye, based on off-the-shelf components. The long-term tracking experiment with in vitro calcium imaging validation demonstrates the system can serve as a powerful tool monitoring the level of genetically-encoded calcium indicator expression, further determining the optimal time window for following experiment.
Collapse
Affiliation(s)
- Yao-Chuan Chang
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, United States of America
| | | | | | | |
Collapse
|
29
|
Liu Z, Kocaoglu OP, Miller DT. 3D Imaging of Retinal Pigment Epithelial Cells in the Living Human Retina. Invest Ophthalmol Vis Sci 2017; 57:OCT533-43. [PMID: 27472277 PMCID: PMC4970801 DOI: 10.1167/iovs.16-19106] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Dysfunction of the retinal pigment epithelium (RPE) underlies numerous retinal pathologies, but biomarkers sensitive to RPE change at the cellular level are limited. In this study, we used adaptive optics optical coherence tomography (AO-OCT) in conjunction with organelle motility as a novel contrast mechanism to visualize RPE cells and characterize their 3-dimensional (3D) reflectance profile. Methods Using the Indiana AO-OCT imaging system (λc = 790 nm), volumes were acquired in the macula of six normal subjects (25–61 years). Volumes were registered in 3D with subcellular accuracy, layers segmented, and RPE and photoreceptor en face images extracted and averaged. Voronoi and two-dimensional (2D) power spectra analyses were applied to the images to quantify RPE and cone packing and cone-to-RPE ratio. Results Adaptive optics OCT revealed two distinct reflectance patterns at the depth of the RPE. One is characterized by the RPE interface with rod photoreceptor tips, the second by the RPE cell nuclei and surrounding organelles, likely melanin. Increasing cell contrast by averaging proved critical for observing the RPE cell mosaic, successful in all subjects and retinal eccentricities imaged. Retinal pigment epithelium mosaic packing and cell thickness generally agreed with that of histology and in vivo studies using other imaging modalities. Conclusions We have presented, to our knowledge, the first detailed characterization of the 3D reflectance profile of individual RPE cells and their relation to cones and rods in the living human retina. Success in younger and older eyes establishes a path for testing aging effects in larger populations. Because the technology is based on OCT, our measurements will aid in interpreting clinical OCT images.
Collapse
|
30
|
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.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Yuhua Zhang
- University of Alabama at Birmingham, Birmingham, USA
| | | | | | | | | | | | | |
Collapse
|
31
|
Sunderland KS, Yang M, Mao C. Phage-Enabled Nanomedicine: From Probes to Therapeutics in Precision Medicine. Angew Chem Int Ed Engl 2017; 56:1964-1992. [PMID: 27491926 PMCID: PMC5311110 DOI: 10.1002/anie.201606181] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Indexed: 01/08/2023]
Abstract
Both lytic and temperate bacteriophages (phages) can be applied in nanomedicine, in particular, as nanoprobes for precise disease diagnosis and nanotherapeutics for targeted disease treatment. Since phages are bacteria-specific viruses, they do not naturally infect eukaryotic cells and are not toxic to them. They can be genetically engineered to target nanoparticles, cells, tissues, and organs, and can also be modified with functional abiotic nanomaterials for disease diagnosis and treatment. This Review will summarize the current use of phage structures in many aspects of precision nanomedicine, including ultrasensitive biomarker detection, enhanced bioimaging for disease diagnosis, targeted drug and gene delivery, directed stem cell differentiation, accelerated tissue formation, effective vaccination, and nanotherapeutics for targeted disease treatment. We will also propose future directions in the area of phage-based nanomedicines, and discuss the state of phage-based clinical trials.
Collapse
Affiliation(s)
- Kegan S Sunderland
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma, 73019, USA
| | - Mingying Yang
- Institute of Applied Bioresource Research, College of Animal Science, Zhejiang University, Yuhangtang Road 866, Hangzhou, Zhejiang, 310058, China
| | - Chuanbin Mao
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma, 73019, USA
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| |
Collapse
|
32
|
Sunderland KS, Yang M, Mao C. Nanomedizin auf Phagenbasis: von Sonden zu Therapeutika für eine Präzisionsmedizin. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201606181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Kegan S. Sunderland
- Department of Chemistry and Biochemistry Stephenson Life Sciences Research Center University of Oklahoma 101 Stephenson Parkway Norman Oklahoma 73019 USA
| | - Mingying Yang
- Institute of Applied Bioresource Research College of Animal Science Zhejiang University Yuhangtang Road 866 Hangzhou Zhejiang 310058 China
| | - Chuanbin Mao
- Department of Chemistry and Biochemistry Stephenson Life Sciences Research Center University of Oklahoma 101 Stephenson Parkway Norman Oklahoma 73019 USA
- School of Materials Science and Engineering Zhejiang University Hangzhou Zhejiang 310027 China
| |
Collapse
|
33
|
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)].
Collapse
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;
| |
Collapse
|
34
|
Morgan JIW. The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay. Ophthalmic Physiol Opt 2016; 36:218-39. [PMID: 27112222 PMCID: PMC4963017 DOI: 10.1111/opo.12289] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/20/2016] [Indexed: 12/24/2022]
Abstract
PURPOSE Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. RECENT FINDINGS Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. SUMMARY Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come.
Collapse
Affiliation(s)
- Jessica I W Morgan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| |
Collapse
|
35
|
Sharma R, Williams DR, Palczewska G, Palczewski K, Hunter JJ. Two-Photon Autofluorescence Imaging Reveals Cellular Structures Throughout the Retina of the Living Primate Eye. Invest Ophthalmol Vis Sci 2016; 57:632-46. [PMID: 26903224 PMCID: PMC4771181 DOI: 10.1167/iovs.15-17961] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 12/30/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Although extrinsic fluorophores can be introduced to label specific cell types in the retina, endogenous fluorophores, such as NAD(P)H, FAD, collagen, and others, are present in all retinal layers. These molecules are a potential source of optical contrast and can enable noninvasive visualization of all cellular layers. We used a two-photon fluorescence adaptive optics scanning light ophthalmoscope (TPF-AOSLO) to explore the native autofluorescence of various cell classes spanning several layers in the unlabeled retina of a living primate eye. METHODS Three macaques were imaged on separate occasions using a custom TPF-AOSLO. Two-photon fluorescence was evoked by pulsed light at 730 and 920 nm excitation wavelengths, while fluorescence emission was collected in the visible range from several retinal layers and different locations. Backscattered light was recorded simultaneously in confocal modality and images were postprocessed to remove eye motion. RESULTS All retinal layers yielded two-photon signals and the heterogeneous distribution of fluorophores provided optical contrast. Several structural features were observed, such as autofluorescence from vessel walls, Müller cell processes in the nerve fibers, mosaics of cells in the ganglion cell and other nuclear layers of the inner retina, as well as photoreceptor and RPE layers in the outer retina. CONCLUSIONS This in vivo survey of two-photon autofluorescence throughout the primate retina demonstrates a wider variety of structural detail in the living eye than is available through conventional imaging methods, and broadens the use of two-photon imaging of normal and diseased eyes.
Collapse
Affiliation(s)
- Robin Sharma
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | | | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| |
Collapse
|
36
|
Abstract
This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye.
Collapse
|
37
|
Yu Y, Zhang T, Meadway A, Wang X, Zhang Y. High-speed adaptive optics for imaging of the living human eye. OPTICS EXPRESS 2015; 23:23035-52. [PMID: 26368408 PMCID: PMC4646518 DOI: 10.1364/oe.23.023035] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 08/10/2015] [Accepted: 08/10/2015] [Indexed: 05/18/2023]
Abstract
The discovery of high frequency temporal fluctuation of human ocular wave aberration dictates the necessity of high speed adaptive optics (AO) correction for high resolution retinal imaging. We present a high speed AO system for an experimental adaptive optics scanning laser ophthalmoscope (AOSLO). We developed a custom high speed Shack-Hartmann wavefront sensor and maximized the wavefront detection speed based upon a trade-off among the wavefront spatial sampling density, the dynamic range, and the measurement sensitivity. We examined the temporal dynamic property of the ocular wavefront under the AOSLO imaging condition and improved the dual-thread AO control strategy. The high speed AO can be operated with a closed-loop frequency up to 110 Hz. Experiment results demonstrated that the high speed AO system can provide improved compensation for the wave aberration up to 30 Hz in the living human eye.
Collapse
Affiliation(s)
- Yongxin Yu
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
- School of Computer Science and Technology, Tianjin University, Tianjin 300072, China
| | - Tianjiao Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Alexander Meadway
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaolin Wang
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Yuhua Zhang
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| |
Collapse
|
38
|
Kusnyerik A, Rozsa B, Veress M, Szabo A, Nemeth J, Maak P. Modeling of in vivo acousto-optic two-photon imaging of the retina in the human eye. OPTICS EXPRESS 2015; 23:23436-23449. [PMID: 26368444 DOI: 10.1364/oe.23.023436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Our aim is to establish a novel combined acousto-optical method for in vivo imaging of the human retina with the two-photon microscope. In this paper we present modeling results based on eye model samples constructed with parameters measured on patients. We used effectively the potential of the electronic compensation offered by the acousto-optic lenses to avoid the use of adaptive optical correction. Simulation predicted lateral resolution between 1.6 µm and 3 µm on the retina. This technology allows the visualization of single cells and promises real time measuring of neural activity in individual neurons, neural segments and cell assemblies with 30-100 µs temporal and subcellular spatial resolution.
Collapse
|
39
|
Advances in retinal ganglion cell imaging. Eye (Lond) 2015; 29:1260-9. [PMID: 26293138 DOI: 10.1038/eye.2015.154] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 06/29/2015] [Indexed: 12/18/2022] Open
Abstract
Glaucoma is one of the leading causes of blindness worldwide and will affect 79.6 million people worldwide by 2020. It is caused by the progressive loss of retinal ganglion cells (RGCs), predominantly via apoptosis, within the retinal nerve fibre layer and the corresponding loss of axons of the optic nerve head. One of its most devastating features is its late diagnosis and the resulting irreversible visual loss that is often predictable. Current diagnostic tools require significant RGC or functional visual field loss before the threshold for detection of glaucoma may be reached. To propel the efficacy of therapeutics in glaucoma, an earlier diagnostic tool is required. Recent advances in retinal imaging, including optical coherence tomography, confocal scanning laser ophthalmoscopy, and adaptive optics, have propelled both glaucoma research and clinical diagnostics and therapeutics. However, an ideal imaging technique to diagnose and monitor glaucoma would image RGCs non-invasively with high specificity and sensitivity in vivo. It may confirm the presence of healthy RGCs, such as in transgenic models or retrograde labelling, or detect subtle changes in the number of unhealthy or apoptotic RGCs, such as detection of apoptosing retinal cells (DARC). Although many of these advances have not yet been introduced to the clinical arena, their successes in animal studies are enthralling. This review will illustrate the challenges of imaging RGCs, the main retinal imaging modalities, the in vivo techniques to augment these as specific RGC-imaging tools and their potential for translation to the glaucoma clinic.
Collapse
|
40
|
Guevara-Torres A, Williams DR, Schallek JB. Imaging translucent cell bodies in the living mouse retina without contrast agents. BIOMEDICAL OPTICS EXPRESS 2015; 6:2106-19. [PMID: 26114032 PMCID: PMC4473747 DOI: 10.1364/boe.6.002106] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 05/05/2015] [Accepted: 05/12/2015] [Indexed: 05/18/2023]
Abstract
The transparency of most retinal cell classes typically precludes imaging them in the living eye; unless invasive methods are used that deploy extrinsic contrast agents. Using an adaptive optics scanning light ophthalmoscope (AOSLO) and capitalizing on the large numerical aperture of the mouse eye, we enhanced the contrast from otherwise transparent cells by subtracting the left from the right half of the light distribution in the detector plane. With this approach, it is possible to image the distal processes of photoreceptors, their more proximal cell bodies and the mosaic of horizontal cells in the living mouse retina.
Collapse
Affiliation(s)
- A. Guevara-Torres
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14620, USA
| | - D. R. Williams
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- The Institute of Optics, University of Rochester, Rochester, NY, 14620, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - J. B. Schallek
- Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA
- Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| |
Collapse
|
41
|
Song H, Latchney L, Williams D, Chung M. Fluorescence adaptive optics scanning laser ophthalmoscope for detection of reduced cones and hypoautofluorescent spots in fundus albipunctatus. JAMA Ophthalmol 2015; 132:1099-104. [PMID: 24922193 DOI: 10.1001/jamaophthalmol.2014.1079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
IMPORTANCE Fundus albipunctatus (FA) is a form of congenital stationary night blindness characterized by yellow-white spots, which were classically described as subretinal. Although night blindness and delayed dark adaptation are hallmarks of this condition, recent studies have described a macular phenotype, particularly among older patients. Using a fluorescence adaptive optics scanning laser ophthalmoscope (FAOSLO), this study provides in vivo morphologic data at the cellular level in FA. OBJECTIVE To study the cone photoreceptors and the albipunctate spots in FA at single-cell resolution. DESIGN, SETTING, AND PARTICIPANT A woman in her 30s with FA underwent a complete ophthalmic examination, including conventional imaging tests, at the University of Rochester. A FAOSLO was used to obtain infrared reflectance images of the cone mosaic at the central fovea and along the superior and temporal meridians to 10° eccentricity. Cone density was measured at the foveal center, and cone spacing was calculated in sampling windows eccentrically. In the area of the albipunctate spots, autofluorescence FAOSLO images (excitation, 561 nm; emission, 624 Δ 40 nm) were simultaneously obtained. MAIN OUTCOMES AND MEASURES Structural appearance of cones, cone density and spacing, and reflectance and autofluorescence of albipunctate spots. RESULTS Cone density was reduced to 70% of the lower limit of the normal range at the foveal center (78.7 × 10(3) cones/mm(2); mean [SD] reference range, 199 [87] × 10(3) cones/mm(2)), and cone spacing was increased eccentrically to 10° (sign test, P = .045). Individual cone central core reflectances appeared dim, suggesting loss of photoreceptor outer segments. The albipunctate spots were hypoautofluorescent. No photoreceptors or retinal pigment epithelium cells were identified at the locations of the albipunctate spots. CONCLUSIONS AND RELEVANCE Although the predominant clinical symptom of night blindness and the electroretinography results suggest a primary rod dysfunction, examination with a FAOSLO demonstrates that cone density is also reduced. This finding may represent an early sign of progression to macular phenotype in FA. The hypoautofluorescence suggests that the albipunctate spots do not represent lipofuscin.
Collapse
Affiliation(s)
- Hongxin Song
- Center for Visual Science, University of Rochester, Rochester, New York
| | - Lisa Latchney
- Flaum Eye Institute, University of Rochester, Rochester, New York
| | - David Williams
- Center for Visual Science, University of Rochester, Rochester, New York3The Institute of Optics, University of Rochester, Rochester, New York
| | - Mina Chung
- Center for Visual Science, University of Rochester, Rochester, New York2Flaum Eye Institute, University of Rochester, Rochester, New York
| |
Collapse
|
42
|
Jiang M, Liu T, Liu X, Jiao S. Simultaneous optical coherence tomography and lipofuscin autofluorescence imaging of the retina with a single broadband light source at 480nm. BIOMEDICAL OPTICS EXPRESS 2014; 5:4242-8. [PMID: 25574436 PMCID: PMC4285602 DOI: 10.1364/boe.5.004242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/20/2014] [Accepted: 10/21/2014] [Indexed: 05/03/2023]
Abstract
We accomplished spectral domain optical coherence tomography and auto-fluorescence microscopy for imaging the retina with a single broadband light source centered at 480 nm. This technique is able to provide simultaneous structural imaging and lipofuscin molecular contrast of the retina. Since the two imaging modalities are provided by the same group of photons, their images are intrinsically registered. To test the capabilities of the technique we periodically imaged the retinas of the same rats for four weeks. The images successfully demonstrated lipofuscin accumulation in the retinal pigment epithelium with aging. The experimental results showed that the dual-modal imaging system can be a potentially powerful tool in the study of age-related degenerative retinal diseases.
Collapse
Affiliation(s)
- Minshan Jiang
- Engineering Research Center of Optical Instruments and Systems, Ministry of Education, Shanghai Key Lab of Modern Optical Systems, University of Shanghai for Science and Technology, No. 516 Jungong Road, Shanghai 200093,
China
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler Street, Miami, Florida, 33174,
USA
| | - Tan Liu
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler Street, Miami, Florida, 33174,
USA
| | - Xiaojing Liu
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler Street, Miami, Florida, 33174,
USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, 10555 W Flagler Street, Miami, Florida, 33174,
USA
| |
Collapse
|
43
|
Imaging retinal ganglion cells: enabling experimental technology for clinical application. Prog Retin Eye Res 2014; 44:1-14. [PMID: 25448921 DOI: 10.1016/j.preteyeres.2014.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/04/2014] [Accepted: 10/18/2014] [Indexed: 11/21/2022]
Abstract
Recent advances in clinical ophthalmic imaging have enhanced patient care. However, the ability to differentiate retinal neurons, such as retinal ganglion cells (RGCs), would advance many areas within ophthalmology, including the screening and monitoring of glaucoma and other optic neuropathies. Imaging at the single cell level would take diagnostics to the next level. Experimental methods have provided techniques and insight into imaging RGCs, however no method has yet to be translated to clinical application. This review provides an overview of the importance of non-invasive imaging of RGCs and the clinically relevant capabilities. In addition, we report on experimental data from wild-type mice that received an in vivo intravitreal injection of a neuronal tracer that labelled RGCs, which in turn were monitored for up to 100 days post-injection with confocal scanning laser ophthalmoscopy. We were able to demonstrate efficient and consistent RGC labelling with this delivery method and discuss the issue of cell specificity. This type of experimental work is important in progressing towards clinically applicable methods for monitoring loss of RGCs in glaucoma and other optic neuropathies. We discuss the challenges to translating these findings to clinical application and how this method of tracking RGCs in vivo could provide valuable structural and functional information to clinicians.
Collapse
|
44
|
Masella BD, Hunter JJ, Williams DR. New wrinkles in retinal densitometry. Invest Ophthalmol Vis Sci 2014; 55:7525-34. [PMID: 25316726 PMCID: PMC4244068 DOI: 10.1167/iovs.13-13795] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 09/30/2014] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact. METHODS An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514-nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared. RESULTS We identified stimulus-related fluctuations in 794-nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (animal 1: 0.073 ± 0.006, animal 2: 0.032 ± 0.003). CONCLUSIONS These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function.
Collapse
Affiliation(s)
- Benjamin D. Masella
- The Institute of Optics, University of Rochester, Rochester, New York, United States
- Center for Visual Science, University of Rochester, Rochester, New York, United States
| | - Jennifer J. Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States
- Flaum Eye Institute, University of Rochester, Rochester, New York, United States
| | - David R. Williams
- The Institute of Optics, University of Rochester, Rochester, New York, United States
| |
Collapse
|
45
|
Abstract
The fovea dominates primate vision, and its anatomy and perceptual abilities are well studied, but its physiology has been little explored because of limitations of current physiological methods. In this study, we adapted a novel in vivo imaging method, originally developed in mouse retina, to explore foveal physiology in the macaque, which permits the repeated imaging of the functional response of many retinal ganglion cells (RGCs) simultaneously. A genetically encoded calcium indicator, G-CaMP5, was inserted into foveal RGCs, followed by calcium imaging of the displacement of foveal RGCs from their receptive fields, and their intensity-response functions. The spatial offset of foveal RGCs from their cone inputs makes this method especially appropriate for fovea by permitting imaging of RGC responses without excessive light adaptation of cones. This new method will permit the tracking of visual development, progression of retinal disease, or therapeutic interventions, such as insertion of visual prostheses.
Collapse
|
46
|
Chui TYP, Dubow M, Pinhas A, Shah N, Gan A, Weitz R, Sulai YN, Dubra A, Rosen RB. Comparison of adaptive optics scanning light ophthalmoscopic fluorescein angiography and offset pinhole imaging. BIOMEDICAL OPTICS EXPRESS 2014; 5:1173-89. [PMID: 24761299 PMCID: PMC3985984 DOI: 10.1364/boe.5.001173] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/18/2014] [Accepted: 02/18/2014] [Indexed: 05/18/2023]
Abstract
Recent advances to the adaptive optics scanning light ophthalmoscope (AOSLO) have enabled finer in vivo assessment of the human retinal microvasculature. AOSLO confocal reflectance imaging has been coupled with oral fluorescein angiography (FA), enabling simultaneous acquisition of structural and perfusion images. AOSLO offset pinhole (OP) imaging combined with motion contrast post-processing techniques, are able to create a similar set of structural and perfusion images without the use of exogenous contrast agent. In this study, we evaluate the similarities and differences of the structural and perfusion images obtained by either method, in healthy control subjects and in patients with retinal vasculopathy including hypertensive retinopathy, diabetic retinopathy, and retinal vein occlusion. Our results show that AOSLO OP motion contrast provides perfusion maps comparable to those obtained with AOSLO FA, while AOSLO OP reflectance images provide additional information such as vessel wall fine structure not as readily visible in AOSLO confocal reflectance images. AOSLO OP offers a non-invasive alternative to AOSLO FA without the need for any exogenous contrast agent.
Collapse
Affiliation(s)
- Toco Y. P. Chui
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
| | - Michael Dubow
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Alexander Pinhas
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nishit Shah
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
| | - Alexander Gan
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
| | - Rishard Weitz
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
| | - Yusufu N. Sulai
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Alfredo Dubra
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233, USA
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Richard B. Rosen
- Department of Ophthalmology, New York Eye & Ear Infirmary, New York, NY 10003, USA
- Department of Ophthalmology, New York Medical College, Valhalla, NY 10595, USA
| |
Collapse
|
47
|
Kozak I. Retinal imaging using adaptive optics technology. Saudi J Ophthalmol 2014; 28:117-22. [PMID: 24843304 DOI: 10.1016/j.sjopt.2014.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/14/2014] [Accepted: 02/16/2014] [Indexed: 11/26/2022] Open
Abstract
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started.
Collapse
Affiliation(s)
- Igor Kozak
- King Khaled Eye Specialist Hospital, Vitreoretinal Division, P.O. Box 7191, Riyadh 11462, Saudi Arabia
| |
Collapse
|
48
|
|
49
|
Meadway A, Girkin CA, Zhang Y. A dual-modal retinal imaging system with adaptive optics. OPTICS EXPRESS 2013; 21:29792-807. [PMID: 24514529 PMCID: PMC3867196 DOI: 10.1364/oe.21.029792] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 11/01/2013] [Accepted: 11/12/2013] [Indexed: 05/20/2023]
Abstract
An adaptive optics scanning laser ophthalmoscope (AO-SLO) is adapted to provide optical coherence tomography (OCT) imaging. The AO-SLO function is unchanged. The system uses the same light source, scanning optics, and adaptive optics in both imaging modes. The result is a dual-modal system that can acquire retinal images in both en face and cross-section planes at the single cell level. A new spectral shaping method is developed to reduce the large sidelobes in the coherence profile of the OCT imaging when a non-ideal source is used with a minimal introduction of noise. The technique uses a combination of two existing digital techniques. The thickness and position of the traditionally named inner segment/outer segment junction are measured from individual photoreceptors. In-vivo images of healthy and diseased human retinas are demonstrated.
Collapse
Affiliation(s)
- Alexander Meadway
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294,
USA
| | - Christopher A. Girkin
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294,
USA
| | - Yuhua Zhang
- Department of Ophthalmology, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294,
USA
- Department of Vision Sciences, University of Alabama at Birmingham, 1530 3rd Avenue South, Birmingham, AL 35294,
USA
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294,
USA
| |
Collapse
|
50
|
Rangel-Fonseca P, Gómez-Vieyra A, Malacara-Hernández D, Wilson MC, Williams DR, Rossi EA. Automated segmentation of retinal pigment epithelium cells in fluorescence adaptive optics images. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2013; 30:2595-604. [PMID: 24323021 DOI: 10.1364/josaa.30.002595] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Adaptive optics (AO) imaging methods allow the histological characteristics of retinal cell mosaics, such as photoreceptors and retinal pigment epithelium (RPE) cells, to be studied in vivo. The high-resolution images obtained with ophthalmic AO imaging devices are rich with information that is difficult and/or tedious to quantify using manual methods. Thus, robust, automated analysis tools that can provide reproducible quantitative information about the cellular mosaics under examination are required. Automated algorithms have been developed to detect the position of individual photoreceptor cells; however, most of these methods are not well suited for characterizing the RPE mosaic. We have developed an algorithm for RPE cell segmentation and show its performance here on simulated and real fluorescence AO images of the RPE mosaic. Algorithm performance was compared to manual cell identification and yielded better than 91% correspondence. This method can be used to segment RPE cells for morphometric analysis of the RPE mosaic and speed the analysis of both healthy and diseased RPE mosaics.
Collapse
|