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Hollaus M, Georgopoulos M, Iby J, Brugger J, Leingang O, Bogunovic H, Schmidt-Erfurth U, Sacu S. Analysing early changes of photoreceptor layer thickness following surgery in eyes with epiretinal membranes. Eye (Lond) 2024; 38:863-870. [PMID: 37875700 DOI: 10.1038/s41433-023-02793-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 09/26/2023] [Accepted: 10/10/2023] [Indexed: 10/26/2023] Open
Abstract
BACKGROUND/OBJECTIVES To analyse short-term changes of mean photoreceptor thickness (PRT) on the ETDRS-grid after vitrectomy and membrane peeling in patients with epiretinal membrane (ERM). SUBJECTS/METHODS Forty-eight patients with idiopathic ERM were included in this prospective study. Study examinations comprised best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) before surgery, 1 week (W1), 1 month (M1) and 3 months (M3) after surgery. Mean PRT was assessed using an automated algorithm and correlated with BCVA and central retinal thickness (CRT). RESULTS Regarding PRT changes of the study eye in comparison to baseline values, a significant decrease at W1 in the 1 mm, 3 mm and 6 mm area (all p-values < 0.001), at M1 (p = 0.009) and M3 (p = 0.019) in the central 1 mm area, a significant increase at M3 in the 6 mm area (p < 0.001), but no significant change at M1 in the 3 mm and 6 mm area and M3 in the 3 mm area (all p-values > 0.05) were observed. BCVA increased significantly from baseline to M3 (0.3LogMAR-0.15LogMAR, Snellen equivalent = 20/40-20/28 respectively; p < 0.001). There was no correlation between baseline PRT and BCVA at any visit after surgery, nor between PRT and BCVA at any visit (all p-values > 0.05). Decrease in PRT in the 1 mm (p < 0.001), 3 mm (p = 0.013) and 6 mm (p = 0.034) area after one week correlated with the increase in CRT (449.9 µm-462.2 µm). CONCLUSIONS Although the photoreceptor layer is morphologically affected by ERMs and after their surgical removal, it is not correlated to BCVA. Thus, patients with photoreceptor layer alterations due to ERM may still benefit from surgery and achieve good functional rehabilitation thereafter.
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Affiliation(s)
- Marlene Hollaus
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
- Vienna Clinical Trial Center, Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Michael Georgopoulos
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Johannes Iby
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
- Vienna Clinical Trial Center, Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Jonas Brugger
- Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria
| | - Oliver Leingang
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
- Laboratory for Ophthalmic Image Analysis, Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Hrvoje Bogunovic
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
- Christian Doppler Lab for Artificial Intelligence in Retina, Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Stefan Sacu
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
- Vienna Clinical Trial Center, Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
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Heitkotter H, Allphin MT, Untaroiu A, Min H, Warr E, Wynne N, Cooper RF, Carroll J. Peak Cone Density Predicted from Outer Segment Length Measured on Optical Coherence Tomography. Curr Eye Res 2024; 49:314-324. [PMID: 38146597 PMCID: PMC10922793 DOI: 10.1080/02713683.2023.2289853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/27/2023] [Indexed: 12/27/2023]
Abstract
PURPOSE To compare peak cone density predicted from outer segment length measured on optical coherence tomography with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy. METHODS Data from 42 healthy participants with direct peak cone density measures and optical coherence tomography line scans available were used in this study. Longitudinal reflectivity profiles were analyzed using two methods of identifying the boundaries of the ellipsoid and interdigitation zones to estimate maximum outer segment length: peak-to-peak and the slope method. These maximum outer segment length values were then used to predict peak cone density using a previously described geometrical model. A comparison between predicted and direct peak cone density measures was then performed. RESULTS The mean bias between observers for estimating maximum outer segment length across methods was less than 2 µm. Cone density predicted from the peak-to-peak method against direct cone density measures showed a mean bias of 6,812 cones/mm2 with 50% of participants displaying a 10% difference or less between predicted and direct cone density values. Cone density derived from the slope method showed a mean bias of -17,929 cones/mm2 relative to direct cone density measures, with only 41% of participants demonstrating less than a 10% difference between direct and predicted cone density values. CONCLUSION Predicted foveal cone density derived from peak-to-peak outer segment length measurements using commercial optical coherence tomography show modest agreement with direct measures of peak cone density from adaptive optics scanning light ophthalmoscopy. The methods used here are imperfect predictors of cone density, however, further exploration of this relationship could reveal a clinically relevant marker of cone structure.
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Affiliation(s)
- Heather Heitkotter
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, USA
| | - Mitchell T. Allphin
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, USA
| | - Ana Untaroiu
- School of Medicine, Medical College of Wisconsin, Milwaukee, USA
| | - Heun Min
- School of Medicine, Medical College of Wisconsin, Milwaukee, USA
| | - Emma Warr
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, USA
| | - Niamh Wynne
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert F. Cooper
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, USA
- Joint Department of Biomedical Engineering Marquette University and Medical College of Wisconsin, Milwaukee, USA
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, USA
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, USA
- Joint Department of Biomedical Engineering Marquette University and Medical College of Wisconsin, Milwaukee, USA
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3
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Schmetterer L, Scholl H, Garhöfer G, Janeschitz-Kriegl L, Corvi F, Sadda SR, Medeiros FA. Endpoints for clinical trials in ophthalmology. Prog Retin Eye Res 2023; 97:101160. [PMID: 36599784 DOI: 10.1016/j.preteyeres.2022.101160] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.
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Affiliation(s)
- Leopold Schmetterer
- Singapore Eye Research Institute, Singapore; SERI-NTU Advanced Ocular Engineering (STANCE), Singapore; Academic Clinical Program, Duke-NUS Medical School, Singapore; School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore; Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria; Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Hendrik Scholl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria
| | - Lucas Janeschitz-Kriegl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Federico Corvi
- Eye Clinic, Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Italy
| | - SriniVas R Sadda
- Doheny Eye Institute, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Felipe A Medeiros
- Vision, Imaging and Performance Laboratory, Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
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Williams DR, Burns SA, Miller DT, Roorda A. Evolution of adaptive optics retinal imaging [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:1307-1338. [PMID: 36950228 PMCID: PMC10026580 DOI: 10.1364/boe.485371] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 02/02/2023] [Indexed: 05/02/2023]
Abstract
This review describes the progress that has been achieved since adaptive optics (AO) was incorporated into the ophthalmoscope a quarter of a century ago, transforming our ability to image the retina at a cellular spatial scale inside the living eye. The review starts with a comprehensive tabulation of AO papers in the field and then describes the technological advances that have occurred, notably through combining AO with other imaging modalities including confocal, fluorescence, phase contrast, and optical coherence tomography. These advances have made possible many scientific discoveries from the first maps of the topography of the trichromatic cone mosaic to exquisitely sensitive measures of optical and structural changes in photoreceptors in response to light. The future evolution of this technology is poised to offer an increasing array of tools to measure and monitor in vivo retinal structure and function with improved resolution and control.
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Affiliation(s)
- David R. Williams
- The Institute of Optics and the Center for
Visual Science, University of Rochester,
Rochester NY, USA
| | - Stephen A. Burns
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Donald T. Miller
- School of Optometry, Indiana
University at Bloomington, Bloomington IN, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and
Vision Science, University of California at Berkeley, Berkeley CA, USA
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5
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Chen S, Abu-Qamar O, Kar D, Messinger JD, Hwang Y, Moult EM, Lin J, Baumal CR, Witkin A, Liang MC, Waheed NK, Curcio CA, Fujimoto JG. Ultrahigh resolution optical coherence tomography markers of normal aging and early age-related macular degeneration. OPHTHALMOLOGY SCIENCE 2023; 3:100277. [PMID: 36970115 PMCID: PMC10034509 DOI: 10.1016/j.xops.2023.100277] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 01/04/2023] [Accepted: 01/26/2023] [Indexed: 02/04/2023]
Abstract
Purpose Ultrahigh resolution spectral domain-OCT (UHR SD-OCT) enables in vivo visualization of micrometric structural markers which differentially associate with normal aging versus age-related macular degeneration (AMD). This study explores the hypothesis that UHR SD-OCT can detect and quantify sub-retinal pigment epithelium (RPE) deposits in early AMD, separating AMD pathology from normal aging. Design Prospective cross-sectional study. Participants A total of 53 nonexudative (dry) AMD eyes from 39 patients, and 63 normal eyes from 39 subjects. Methods Clinical UHR SD-OCT scans were performed using a high-density protocol. Exemplary high-resolution histology and transmission electron microscopy images were obtained from archive donor eyes. Three trained readers evaluated and labeled outer retina morphological features, including the appearance of a hyporeflective split within the RPE-RPE basal lamina (RPE-BL)-Bruch's membrane (BrM) complex on UHR brightness (B)-scans. A semi-automatic segmentation algorithm measured the thickness of the RPE-BL-BrM split/hyporeflective band. Main Outcome Measures Qualitative description of outer retinal morphological changes on UHR SD-OCT B-scans; the proportion of the RPE-BL-BrM complex with visible split (%) and the thickness of the resulting hyporeflective band (μm). Results In young normal eyes, UHR SD-OCT consistently revealed an RPE-BL-BrM split/hyporeflective band. Its visibility and thickness were less in eyes of advanced age. However, the split/hyporeflective band was again visible in early AMD eyes. Both qualitative reading and quantitative thickness measurements showed significantly elevated visibility and thickness of the RPE-BL-BrM split/hyporeflective in early AMD eyes compared to age-matched controls. Conclusions Our imaging results strongly support the hypothesis that appearance of the RPE-BL-BrM split/hyporeflective band in older subjects is dominated by the BL deposit, an indicator of early AMD well known from histology. Ultrahigh resolution SD-OCT can be used to investigate physiological aging as well as early AMD pathology in clinical imaging studies. Developing quantifiable markers associated with disease pathogenesis and progression can facilitate drug discovery, as well as reduce clinical trial times. Financial Disclosures Proprietary or commercial disclosure may be found after the references.
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Kim TH, Ma G, Son T, Yao X. Functional Optical Coherence Tomography for Intrinsic Signal Optoretinography: Recent Developments and Deployment Challenges. Front Med (Lausanne) 2022; 9:864824. [PMID: 35445037 PMCID: PMC9013890 DOI: 10.3389/fmed.2022.864824] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/16/2022] [Indexed: 11/13/2022] Open
Abstract
Intrinsic optical signal (IOS) imaging of the retina, also termed as optoretinogram or optoretinography (ORG), promises a non-invasive method for the objective assessment of retinal function. By providing the unparalleled capability to differentiate individual retinal layers, functional optical coherence tomography (OCT) has been actively investigated for intrinsic signal ORG measurements. However, clinical deployment of functional OCT for quantitative ORG is still challenging due to the lack of a standardized imaging protocol and the complication of IOS sources and mechanisms. This article aims to summarize recent developments of functional OCT for ORG measurement, OCT intensity- and phase-based IOS processing. Technical challenges and perspectives of quantitative IOS analysis and ORG interpretations are discussed.
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Affiliation(s)
- Tae-Hoon Kim
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Guangying Ma
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Taeyoon Son
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Xincheng Yao
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, United States
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
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7
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Werner JS, Gorczynska I, Spillmann L. Heinrich Müller (1820-1864) and the entoptic discovery of the site in the retina where vision is initiated. JOURNAL OF THE HISTORY OF THE NEUROSCIENCES 2022; 31:64-90. [PMID: 34720038 DOI: 10.1080/0964704x.2021.1959165] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heinrich Müller was a nineteenth-century German retinal anatomist who, during his short career, was one of the discoverers of the rod photopigment rhodopsin and neuroglia in the retina, now known as Müller cells. He also described the ocular muscles and double foveae of some birds. An important, but largely neglected, insight by Müller was to combine careful psychophysical measurements and geometrical optics to find the location of the photosensitive layer of the retina in the living eye. Here, we provide translated passages from Müller's (1855) publication and compare his entoptic observations with retinal imaging using optical coherence tomography. Müller correctly deduced from his careful experiments that vision is initiated in the photoreceptors located in the back of the retina.
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Affiliation(s)
- John S Werner
- UC Davis Eye Center, University of California, Davis, Sacramento, California, USA
| | - Iwona Gorczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicholaus Copernicus University, Torun, Poland
| | - Lothar Spillmann
- Department of Neurology, University of Freiburg, Freiburg, Germany
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8
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Jonnal RS. Toward a clinical optoretinogram: a review of noninvasive, optical tests of retinal neural function. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1270. [PMID: 34532407 PMCID: PMC8421939 DOI: 10.21037/atm-20-6440] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 07/12/2021] [Indexed: 11/17/2022]
Abstract
The past few years have witnessed rapid development of the optoretinogram—a noninvasive, optical measurement of neural function in the retina, and especially the photoreceptors (Ph). While its recent development has been rapid, it represents the culmination of hundreds of experiments spanning decades. Early work showed measurable and reproducible changes in the optical properties of retinal explants and suspensions of Ph, and uncovered some of the biophysical and biochemical mechanisms underlying them. That work thus provided critical motivation for more recent work based on clinical imaging platforms, whose eventual goal is the improvement of ophthalmic care and streamlining the discovery of novel therapeutics. The first part of this review consists of a selective summary of the early work, and identifies four kinds of stimulus-evoked optical signals that have emerged from it: changes in light scattered from the membranous discs of the Ph’s outer segment (OS), changes in light scattered by the front and back boundaries of the OS, rearrangement of scattering material in and near the OS, and changes in the OS length. In the past decade, all four of these signals have continued to be investigated using imaging systems already used in the clinic or intended for clinical and translational use. The second part of this review discusses these imaging modalities, their potential to detect and quantify the signals of interest, and other factors influencing their translational promise. Particular attention is paid to phase-sensitive optical coherence tomography (OCT) with adaptive optics (AO), a method in which both the amplitude and the phase of light reflected from individual Ph is monitored as visible stimuli are delivered to them. The record of the light’s phase is decoded to reveal a reproducible pattern of deformation in the OS, while the amplitude reveals changes in scattering and structural rearrangements. The method has been demonstrated in a few labs and has been used to measure responses from both rods and cones. With the ability to detect responses to stimuli isomerizing less than 0.01% of photopigment, this technique may prove to be a quick, noninvasive, and objective way to measure subtle disease-related dysfunction at the cellular level, and thus to provide an entirely new and complementary biomarker for retinal disease and recovery.
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Affiliation(s)
- Ravi S Jonnal
- Department of Ophthalmology and Vision Science, University of California, Davis, CA, USA
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9
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Cideciyan AV, Krishnan AK, Roman AJ, Sumaroka A, Swider M, Jacobson SG. Measures of Function and Structure to Determine Phenotypic Features, Natural History, and Treatment Outcomes in Inherited Retinal Diseases. Annu Rev Vis Sci 2021; 7:747-772. [PMID: 34255540 DOI: 10.1146/annurev-vision-032321-091738] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inherited retinal diseases (IRDs) are at the forefront of innovative gene-specific treatments because of the causation by single genes, the availability of microsurgical access for treatment delivery, and the relative ease of quantitative imaging and vision measurement. However, it is not always easy to choose a priori, from scores of potential measures, an appropriate subset to evaluate efficacy outcomes considering the wide range of disease stages with different phenotypic features. This article reviews measurements of visual function and retinal structure that our group has used over the past three decades to understand the natural history of IRDs. We include measures of light sensitivity, retinal structure, mapping of natural fluorophores, evaluation of pupillary light reflex, and oculomotor control. We provide historical context and examples of applicability. We also review treatment trial outcomes using these measures of function and structure. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Arun K Krishnan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Alejandro J Roman
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Alexander Sumaroka
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Malgorzata Swider
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
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10
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Yao X, Son T, Kim TH, Le D. Interpretation of anatomic correlates of outer retinal bands in optical coherence tomography. Exp Biol Med (Maywood) 2021; 246:2140-2150. [PMID: 34111984 DOI: 10.1177/15353702211022674] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
By providing the sectioning capability to differentiate individual retinal layers, optical coherence tomography (OCT) is revolutionizing eye disease diagnosis and treatment evaluation. A better understanding of the hyper- and hypo-reflective bands in retinal OCT is essential for accurate interpretation of clinical outcomes. In this article, we summarize the interpretations of clinical OCT and adaptive optics (AO) OCT (AO-OCT) of the outer retina in the human eye, and briefly review OCT investigation of the outer retina in animal models. Quantitative analysis of outer retinal OCT bands is compared to established parameters of retinal histology. The literature review and comparative analysis support that both inner/outer segment (IS/OS) junction and IS ellipsoid zone nonexclusively contribute to the second band; and OS, OS tips, and retinal pigment epithelium apical processes contribute to the third band in conventional OCT. In contrast, AO-OCT might predominantly detect the IS/OS junction and OS tip signals at the second and third bands due to its improved sectioning capability and possible AO effect on the sensitivities for recording ballistic and diffusive photons from different regions of the outer retina.
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Affiliation(s)
- Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.,Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Taeyoon Son
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Tae-Hoon Kim
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - David Le
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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11
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Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT). PLoS One 2021; 16:e0245293. [PMID: 33412568 PMCID: PMC7790532 DOI: 10.1371/journal.pone.0245293] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/25/2020] [Indexed: 12/18/2022] Open
Abstract
Purpose To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT). Methods Study population. Twenty healthy eyes of ten subjects (age 23 to 67). Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and full en-face plane (FEF) combining signals from all mentioned cone layers. Additionally, reliability of a simple semi-automated approach for assessment of cone density was tested. Main outcome measures. Cone density of IS/OS, IS/OS+, COST and FEF. Qualitative depiction and composition of each cone layer. Inter-rater agreement of cone density measurements. Results Mean overall cone density at all eccentricities was highest at the FEF plane (21.160/mm2), followed by COST (20.450/mm2), IS/OS+ (19.920/mm2) and IS/OS (19.530/mm2). The different meridians and eccentricities had a significant impact on cone density, with lower eccentricity resulting in higher cone densities (p≤.001), which were highest at the nasal, then temporal, then inferior and then superior meridian. Depiction of the cone mosaic differed between all 4 layers regarding signal size and packing density. Therefore, different cone layers showed evident but not complete signal overlap. Using the semi-automated technique for counting of cone signals achieved high inter-rater reliability (ICC > .99). Conclusions In healthy individuals qualitative and quantitative changes in cone signals are found not only in different eccentricities and meridians, but also within different photoreceptor layers. The variation between cone planes has to be considered when assessing the integrity of cone photoreceptors in healthy and diseased eyes using adaptive optics technology.
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12
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Reumueller A, Wassermann L, Salas M, Schranz M, Told R, Kostolna K, Drexler W, Pircher M, Schmidt-Erfurth U, Pollreisz A. Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT). OPTICS EXPRESS 2020; 28:36723-36739. [PMID: 33379760 DOI: 10.1364/oe.409076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/08/2020] [Indexed: 06/12/2023]
Abstract
An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean overall cone density was 19,892/mm2 at ecc 2.5° and 13,323/mm2 at ecc 6.5°. A significant impact on cone density was found for eccentricity (up to 6,700/mm2 between ecc 2.5° and 6.5°), meridian (up to 3,700/mm2 between nasal and superior meridian) and layer (up to 1,400/mm2 between FEF and IS/OS). Age showed only a weak negative effect. These factors as well as inter-individual variability have to be taken into account when comparing cone density measurements between healthy and pathologically changed eyes, as their combined effect on density can easily exceed several thousand cones per mm2 even in parafoveal regions.
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13
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Valente D, Vienola KV, Zawadzki RJ, Jonnal RS. Kilohertz retinal FF-SS-OCT and flood imaging with hardware-based adaptive optics. BIOMEDICAL OPTICS EXPRESS 2020; 11:5995-6011. [PMID: 33150001 PMCID: PMC7587251 DOI: 10.1364/boe.403509] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 05/18/2023]
Abstract
A retinal imaging system was designed for full-field (FF) swept-source (SS) optical coherence tomography (OCT) with cellular resolution. The system incorporates a real-time adaptive optics (AO) subsystem and a very high-speed CMOS sensor, and is capable of acquiring volumetric images of the retina at rates up to 1 kHz. While digital aberration correction (DAC) is an attractive potential alternative to AO, it has not yet been shown to provide resolution allowing visualization of cones in the fovea, where early detection of functional deficits is most critical. Here we demonstrate that FF-SS-OCT with hardware AO permits resolution of foveal cones, imaged at eccentricities of 1° and 2°, with volume rates adequate to measure light-evoked changes in photoreceptors. With the reference arm blocked, the system can operate as a kilohertz AO flood illumination fundus camera with adjustable temporal coherence and is expected to allow measurement of light-evoked changes caused by common path interference in photoreceptor outer segments (OS). In this paper, we describe the system's optical design, characterize its performance, and demonstrate its ability to produce images of the human photoreceptor mosaic.
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Affiliation(s)
- Denise Valente
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Kari V. Vienola
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
- EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA 95616, USA
| | - Ravi S. Jonnal
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
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Miller DT, Kurokawa K. Cellular-Scale Imaging of Transparent Retinal Structures and Processes Using Adaptive Optics Optical Coherence Tomography. Annu Rev Vis Sci 2020; 6:115-148. [PMID: 32609578 PMCID: PMC7864592 DOI: 10.1146/annurev-vision-030320-041255] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
High-resolution retinal imaging is revolutionizing how scientists and clinicians study the retina on the cellular scale. Its exquisite sensitivity enables time-lapse optical biopsies that capture minute changes in the structure and physiological processes of cells in the living eye. This information is increasingly used to detect disease onset and monitor disease progression during early stages, raising the possibility of personalized eye care. Powerful high-resolution imaging tools have been in development for more than two decades; one that has garnered considerable interest in recent years is optical coherence tomography enhanced with adaptive optics. State-of-the-art adaptive optics optical coherence tomography (AO-OCT) makes it possible to visualize even highly transparent cells and measure some of their internal processes at all depths within the retina, permitting reconstruction of a 3D view of the living microscopic retina. In this review, we report current AO-OCT performance and its success in visualizing and quantifying these once-invisible cells in human eyes.
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Affiliation(s)
- Donald T Miller
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
| | - Kazuhiro Kurokawa
- School of Optometry, Indiana University, Bloomington, Indiana 47405, USA; ,
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15
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Reumueller A, Wassermann L, Salas M, Karantonis MG, Sacu S, Georgopoulos M, Drexler W, Pircher M, Pollreisz A, Schmidt-Erfurth U. Morphologic and Functional Assessment of Photoreceptors After Macula-Off Retinal Detachment With Adaptive-Optics OCT and Microperimetry. Am J Ophthalmol 2020; 214:72-85. [PMID: 31883465 DOI: 10.1016/j.ajo.2019.12.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 12/21/2022]
Abstract
PURPOSE Limited information is available on morphologic and functional regeneration of photoreceptors after retinal detachment (RD) surgery. This observational clinical study compared morphologic and functional changes of cones after vitrectomy for macula-off retinal detachment. DESIGN Prospective, fellow-eye comparative case series. METHODS StudyPopulation: Five eyes after vitrectomy with gas for macula-off retinal detachment (retinal detachment eyes, RDE) and 5 healthy fellow eyes (HFE) of 5 patients (mean age 59.8 years, macula-off duration 0.5 days to 5.5 days). ObservationProcedures: Eyes were examined with adaptive-optics optical coherence tomography (AO-OCT), spectral-domain OCT (SDOCT), and microperimetry (MP) at 6 (baseline, BL) and 56 weeks (follow-up, FUP) after 23 gauge pars plana vitrectomy and SF6 gas tamponade. Eight corresponding regions at foveal eccentricities of 2.5° (ecc 2.5°) and 6.5° (ecc 6.5°) were analyzed in every eye. AO-OCT en face images and SD-OCT B-scans were graded regarding irregularity and loss of photoreceptor signals ranging from none to severe changes. The number of detectable cones at height of the inner-outer segment junction (IS/OS) and cone outer segment tips (COST) was counted manually in AO-OCT images. MP with a custom grid was used to assess retinal sensitivity at these locations. MainOutcomeMeasures: Cone density, cone pattern regularity and signal attenuation, retinal sensitivity. RESULTS In comparison to HFE, RDE showed highly irregular cone patterns in AO-OCT and irregular outer retinal bands in SDOCT. Despite significant improvement of cone pattern regularity compared to BL (P < .001), 63% of AO images showed remaining cone pattern irregularity and 45.5% of SDOCT B-scans showed severe signal reduction at FUP. In HFE, mean cone density retrieved from IS/OS and COST remained around 20,000/mm2 (ecc 2.5°) and 16,000/mm2 (ecc 6.5°) at BL and FUP. Cone density of RDE was significantly reduced and ranged between 200/mm2 and 15,600/mm2 (P < .001) at BL. Despite improvement at FUP (P < .001), mean cone density at IS/OS and COST was still lower compared to HFE and ranged between 7790 and 9555 cones/mm2 (P < .001). Mean retinal sensitivity of all measured locations remained 18 dB in HFE and was significantly lower in RDE, with 14.30 dB at BL and 14.64 dB at FUP. Both SDOCT grading and microperimetry sensitivity showed strong correlation with AO-OCT grading and cone density (rho values > 0.750). CONCLUSIONS The combination of AO-OCT, SDOCT, and microperimetry is a powerful tool to capture cone regeneration after vitreoretinal surgery. Our study shows that cone morphology and function improve within 56 weeks after RD surgery but structural and functional impairment is still present.
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Affiliation(s)
- Adrian Reumueller
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Lorenz Wassermann
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | | | - Stefan Sacu
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Michael Georgopoulos
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Drexler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Andreas Pollreisz
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
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16
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Menghini M, Cehajic-Kapetanovic J, MacLaren RE. Monitoring progression of retinitis pigmentosa: current recommendations and recent advances. Expert Opin Orphan Drugs 2020; 8:67-78. [PMID: 32231889 PMCID: PMC7104334 DOI: 10.1080/21678707.2020.1735352] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Retinitis pigmentosa (RP) is the most common form of inherited retinal degenerations with an estimated prevalence of 1 in 4,000 and more than 1 million individuals affected worldwide. With the introduction of the first retinal gene therapy in 2017 the importance of understanding the mechanisms of retinal degeneration and its natural progression has shifted from being of academic interest to being of pivotal for the development of new therapies. AREAS COVERED This review covers standard and innovative diagnostic techniques and complementary examinations needed for the evaluation and treatment of RP. It includes chapters on the assessment of visual function, retinal morphology, and genotyping. EXPERT OPINION Monitoring the progression of RP can best be achieved by combining assessments of both visual function and morphology. Visual acuity testing using ETDRS charts should be complemented by low-luminance visual acuity and colour vision tests. Assessment of the visual field can also be useful in less advanced cases. In those with central RP involvement measuring retinal sensitivity using microperimetry is recommended. Retinal morphology is best assessed by OCT and autofluorescence. Genetic testing is pivotal as it contributes to the pathophysiological understanding and can guide clinical management as well as identify individuals that could benefit from retinal gene therapy.
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Affiliation(s)
- Moreno Menghini
- Oxford Eye Hospital and Nuffield Department of Clinical Neurosciences, Oxford University, The John Radcliffe Hospital, West Wing, Oxford OX3 9DU, United Kingdom, +41 79 704 52 58
| | - Jasmina Cehajic-Kapetanovic
- Oxford Eye Hospital and Nuffield Department of Clinical Neurosciences, Oxford University, The John Radcliffe Hospital, West Wing, Oxford OX3 9DU, United Kingdom, +44 7725 197054
| | - Robert E MacLaren
- Oxford Eye Hospital and Nuffield Department of Clinical Neurosciences, Oxford University, The John Radcliffe Hospital, West Wing, Oxford OX3 9DU, United Kingdom, +44 1865 228974
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ATTENUATION OUTER RETINAL BANDS ON OPTICAL COHERENCE TOMOGRAPHY FOLLOWING MACULAR EDEMA: A Possible Manifestation of Photoreceptor Misalignment. Retina 2020; 40:2232-2239. [PMID: 31922497 DOI: 10.1097/iae.0000000000002738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Macular edema is a common retinal disease which may leave important anatomical and functional sequelaes. Directional fundus imaging consists of comparing on- and off-axis images to reveal angle-dependent reflectance properties of fundus structures, which may be related to misaligned photoreceptors. Here, we analyzed directional optical coherence tomography (OCT) and flood-illumination adaptive optics ophthalmoscopy images to detect evidence of misaligned photoreceptors following macular edema. METHODS Transversal, observational study. Nine patients having recovered a normal macular profile after macular edema due to retinal vein occlusion were included. For each patient, a reference OCT scan (i.e., with the incident beam normal to the fovea) was acquired, and off-axis scans were then acquired by laterally shifting the entry pupil. In addition, in four of these eyes, directional adaptive optics ophthalmoscopy documented the directional variations of cone metrics. RESULTS Included patients comprised two women and seven men (age range, 19-76 years). Reference OCT scans showed patchy attenuation of the cone outer segment tips and to a lesser extent of the inner segment/outer segment lines in all, but two eyes; these. Increased intensity of the cone outer segment tips and inner segment/outer segment lines could be observed on off-axis scans. Accordingly, fusion images showed 66% average reduction of the length of cone outer segment tips attenuation. In two cases, although reference scans showed continuity of outer bands, focal attenuation was evidenced in off-axis images. Directional adaptive optics ophthalmoscopy imaging showed a strong directional variability of cone counts in these areas, ranging from near absence to roughly two-third of reference values. In each case, directional variations of cone counts paralleled those of the reflectance of outer bands. CONCLUSION After macular edema, focal attenuations of the inner segment/outer segment and of the cone outer segment tips lines may be present on OCT. These areas may show a strong directional variability by both OCT and adaptive optics ophthalmoscopy, suggesting that misaligned photoreceptor outer segments contribute to such features. The evaluation of outer retinal damage following macular edema should therefore take into account the optical Stiles-Crawford effect to disambiguate missing from misaligned cones.
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18
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Cuenca N, Ortuño-Lizarán I, Sánchez-Sáez X, Kutsyr O, Albertos-Arranz H, Fernández-Sánchez L, Martínez-Gil N, Noailles A, López-Garrido JA, López-Gálvez M, Lax P, Maneu V, Pinilla I. Interpretation of OCT and OCTA images from a histological approach: Clinical and experimental implications. Prog Retin Eye Res 2020; 77:100828. [PMID: 31911236 DOI: 10.1016/j.preteyeres.2019.100828] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/16/2019] [Accepted: 12/30/2019] [Indexed: 12/17/2022]
Abstract
Optical coherence tomography (OCT) and OCT angiography (OCTA) have been a technological breakthrough in the diagnosis, treatment, and follow-up of many retinal diseases, thanks to its resolution and its ability to inform of the retinal state in seconds, which gives relevant information about retinal degeneration. In this review, we present an immunohistochemical description of the human and mice retina and we correlate it with the OCT bands in health and pathological conditions. Here, we propose an interpretation of the four outer hyperreflective OCT bands with a correspondence to retinal histology: the first and innermost band as the external limiting membrane (ELM), the second band as the cone ellipsoid zone (EZ), the third band as the outer segment tips phagocytosed by the pigment epithelium (PhaZ), and the fourth band as the mitochondria in the basal portion of the RPE (RPEmitZ). The integrity of these bands would reflect the health of photoreceptors and retinal pigment epithelium. Moreover, we describe how the vascular plexuses vary in different regions of the healthy human and mice retina, using OCTA and immunohistochemistry. In humans, four, three, two or one plexuses can be observed depending on the distance from the fovea. Also, specific structures such as vascular loops in the intermediate capillary plexus, or spider-like structures of interconnected capillaries in the deep capillary plexus are found. In mice, three vascular plexuses occupy the whole retina, except in the most peripheral retina where only two plexuses are found. These morphological issues should be considered when assessing a pathology, as some retinal diseases are associated with structural changes in blood vessels. Therefore, the analysis of OCT bands and OCTA vascular plexuses may be complementary for the diagnosis and prognosis of retinal degenerative processes, useful to assess therapeutic approaches, and it is usually correlated to visual acuity.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain; Institute Ramón Margalef, University of Alicante, Alicante, Spain.
| | | | - Xavier Sánchez-Sáez
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Oksana Kutsyr
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | | | | | - Natalia Martínez-Gil
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Agustina Noailles
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | | | | | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa, University Hospital, Zaragoza, Spain
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Automated Quantification of Macular Ellipsoid Zone Intensity in Glaucoma Patients: the Method and its Comparison with Manual Quantification. Sci Rep 2019; 9:19771. [PMID: 31875050 PMCID: PMC6930206 DOI: 10.1038/s41598-019-56337-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 12/05/2019] [Indexed: 11/08/2022] Open
Abstract
The macular ellipsoid zone intensity (mEZi) is a known marker of disease severity in a number of diverse ocular diseases. The purpose of this study was to establish an automated method (AM) for mEZi quantification and to compare the method's performance with that of a manual method (MM) for glaucoma patients and healthy controls. Seventy-one (71) mild-to-moderate glaucoma patients, 71 severe-glaucoma patients, and 51 controls were enrolled. Both calibration (n = 160) and validation (n = 33) image sets were compiled. The correlation of AM to MM quantification was assessed by Deming regression for the calibration set, and a compensation formula was generated. Then, for each image in the validation set, the compensated AM quantification was compared with the mean of five repetitive MM quantifications. The AM quantification of the calibration set was found to be linearly correlated with MM in the normal-to-severe-stage glaucoma patients (R2 = 0.914). The validation set's compensated AM quantification produced R2 = 0.991, and the relationship between the 2 quantifications was AM = 1.004(MM) + 0.139. In the validation set, the compensated AM quantification fell within MM quantification's 95% confidence interval in 96.9% of the images. An AM for mEZi quantification was calibrated and validated relative to MM quantification for both glaucoma patients and healthy controls.
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20
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Meadway A, Sincich LC. Light reflectivity and interference in cone photoreceptors. BIOMEDICAL OPTICS EXPRESS 2019; 10:6531-6554. [PMID: 31853415 PMCID: PMC6913404 DOI: 10.1364/boe.10.006531] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/31/2019] [Accepted: 11/03/2019] [Indexed: 05/04/2023]
Abstract
In several modes of retinal imaging, the primary means of visualizing cone photoreceptors is from reflected light. Understanding how such images are formed, particularly when adaptive optics techniques are used, will help to guide their interpretation. Toward this end, we used finite difference beam propagation to model reflections from cone photoreceptors. We investigated the formation of cone images in adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography (AOOCT). Three cone models were tested, one made up of three segments of varying refractive index, the other two having additional boundaries at the inner/outer segment junction and outer segment tip. Images formed by the first model did not correspond to AOOCT observations in the literature, while the latter two did. The predicted distributions of reflected light intensity from the latter cone models were compared to the distribution from AOSLO images, both studied with light sources of varied coherence length. The cone model with the most reflections at the inner/outer segment junction best fit the data measured in vivo. These results show that variance in cone reflection can originate from light interfering from reflectors much more closely spaced than the outer segment length. We also show that subtracting images taken with different coherence length sources highlights these changes in interference. Differential coherence images of cones occasionally revealed an annular reflection profile, which modeling showed to be very sensitive to cone size and the gaps bracketing the outer segment, suggesting that such imaging may be useful for probing photoreceptor morphology.
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Affiliation(s)
- Alexander Meadway
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lawrence C. Sincich
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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21
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Meleppat RK, Zhang P, Ju MJ, Manna SK, Jian Y, Pugh EN, Zawadzki RJ. Directional optical coherence tomography reveals melanin concentration-dependent scattering properties of retinal pigment epithelium. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-10. [PMID: 31254332 PMCID: PMC6977406 DOI: 10.1117/1.jbo.24.6.066011] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/30/2019] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT) is a powerful tool in ophthalmology that provides in vivo morphology of the retinal layers and their light scattering properties. The directional (angular) reflectivity of the retinal layers was investigated with focus on the scattering from retinal pigment epithelium (RPE). The directional scattering of the RPE was studied in three mice strains with three distinct melanin concentrations: albino (BALB/c), agouti (129S1/SvlmJ), and strongly pigmented (C57BL/6J). The backscattering signal strength was measured with a directional OCT system in which the pupil entry position of the narrow OCT beam can be varied across the dilated pupil of the eyes of the mice. The directional reflectivity of other retinal melanin-free layers, including the internal and external limiting membranes, and Bruch's membrane (albinos) were also measured and compared between the strains. The intensity of light backscattered from these layers was found highly sensitive to the angle of illumination, whereas the inner/outer segment (IS/OS) junctions showed a reduced sensitivity. The reflections from the RPE are largely insensitive in highly pigmented mice. The differences in directional scattering between strains shows that directionality decreases with an increase in melanin concentrations in RPE, suggesting increasing contribution of Mie scattering by melanosomes.
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Affiliation(s)
- Ratheesh K. Meleppat
- University of California Davis, UC Davis Eyepod, Department of Cell Biology and Human Anatomy, Davis, California, United States
| | - Pengfei Zhang
- University of California Davis, UC Davis Eyepod, Department of Cell Biology and Human Anatomy, Davis, California, United States
| | - Myeong Jin Ju
- Simon Fraser University, School of Engineering Science, Burnaby, British Columbia, Canada
| | - Suman K. Manna
- University of California Davis, UC Davis Eyepod, Department of Cell Biology and Human Anatomy, Davis, California, United States
| | - Yifan Jian
- Oregon Science and Health University, Casey Eye Institute, Portland, Oregon, United States
| | - Edward N. Pugh
- University of California Davis, UC Davis Eyepod, Department of Cell Biology and Human Anatomy, Davis, California, United States
| | - Robert J. Zawadzki
- University of California Davis, UC Davis Eyepod, Department of Cell Biology and Human Anatomy, Davis, California, United States
- University of California Davis, UC Davis Eye Center, Department of Ophthalmology and Vision Science, Sacramento, California, United States
- Address all correspondence to Robert J. Zawadzki, E-mail:
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22
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Sajdak BS, Salmon AE, Cava JA, Allen KP, Freling S, Ramamirtham R, Norton TT, Roorda A, Carroll J. Noninvasive imaging of the tree shrew eye: Wavefront analysis and retinal imaging with correlative histology. Exp Eye Res 2019; 185:107683. [PMID: 31158381 DOI: 10.1016/j.exer.2019.05.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/21/2019] [Accepted: 05/28/2019] [Indexed: 02/08/2023]
Abstract
Tree shrews are small mammals with excellent vision and are closely related to primates. They have been used extensively as a model for studying refractive development, myopia, and central visual processing and are becoming an important model for vision research. Their cone dominant retina (∼95% cones) provides a potential avenue to create new damage/disease models of human macular pathology and to monitor progression or treatment response. To continue the development of the tree shrew as an animal model, we provide here the first measurements of higher order aberrations along with adaptive optics scanning light ophthalmoscopy (AOSLO) images of the photoreceptor mosaic in the tree shrew retina. To compare intra-animal in vivo and ex vivo cone density measurements, the AOSLO images were matched to whole-mount immunofluorescence microscopy. Analysis of the tree shrew wavefront indicated that the optics are well-matched to the sampling of the cone mosaic and is consistent with the suggestion that juvenile tree shrews are nearly emmetropic (slightly hyperopic). Compared with in vivo measurements, consistently higher cone density was measured ex vivo, likely due to tissue shrinkage during histological processing. Tree shrews also possess massive mitochondria ("megamitochondria") in their cone inner segments, providing a natural model to assess how mitochondrial size affects in vivo retinal imagery. Intra-animal in vivo and ex vivo axial distance measurements were made in the outer retina with optical coherence tomography (OCT) and transmission electron microscopy (TEM), respectively, to determine the origin of sub-cellular cone reflectivity seen on OCT. These results demonstrate that these megamitochondria create an additional hyper-reflective outer retinal reflective band in OCT images. The ability to use noninvasive retinal imaging in tree shrews supports development of this species as a model of cone disorders.
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Affiliation(s)
- Benjamin S Sajdak
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States; Morgridge Institute for Research, Madison, WI, United States
| | - Alexander E Salmon
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Jenna A Cava
- Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Kenneth P Allen
- Biomedical Resource Center, Medical College of Wisconsin, Milwaukee, WI, United States; Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Susan Freling
- Max Planck Florida Institute for Neuroscience, Jupiter, FL, United States
| | - Ramkumar Ramamirtham
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States
| | - Thomas T Norton
- Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA, United States
| | - Joseph Carroll
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States.
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Cottaris NP, Jiang H, Ding X, Wandell BA, Brainard DH. A computational-observer model of spatial contrast sensitivity: Effects of wave-front-based optics, cone-mosaic structure, and inference engine. J Vis 2019; 19:8. [PMID: 30943530 DOI: 10.1167/19.4.8] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We present a computational-observer model of the human spatial contrast-sensitivity function based on the Image Systems Engineering Toolbox for Biology (ISETBio) simulation framework. We demonstrate that ISETBio-derived contrast-sensitivity functions agree well with ones derived using traditional ideal-observer approaches, when the mosaic, optics, and inference engine are matched. Further simulations extend earlier work by considering more realistic cone mosaics, more recent measurements of human physiological optics, and the effect of varying the inference engine used to link visual representations to psychophysical performance. Relative to earlier calculations, our simulations show that the spatial structure of realistic cone mosaics reduces the upper bounds on performance at low spatial frequencies, whereas realistic optics derived from modern wave-front measurements lead to increased upper bounds at high spatial frequencies. Finally, we demonstrate that the type of inference engine used has a substantial effect on the absolute level of predicted performance. Indeed, the performance gap between an ideal observer with exact knowledge of the relevant signals and human observers is greatly reduced when the inference engine has to learn aspects of the visual task. ISETBio-derived estimates of stimulus representations at various stages along the visual pathway provide a powerful tool for computing the limits of human performance.
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Affiliation(s)
- Nicolas P Cottaris
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Haomiao Jiang
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Xiaomao Ding
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian A Wandell
- Department of Psychology, Stanford University, Stanford, CA, USA
| | - David H Brainard
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
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24
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Reumueller A, Schmidt-Erfurth U, Salas M, Sacu S, Drexler W, Pircher M, Pollreisz A. Three-Dimensional Adaptive Optics–Assisted Visualization of Photoreceptors in Healthy and Pathologically Aged Eyes. ACTA ACUST UNITED AC 2019; 60:1144-1155. [DOI: 10.1167/iovs.18-25702] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Adrian Reumueller
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| | - Stefan Sacu
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Drexler
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| | - Andreas Pollreisz
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
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Rodrigues MW, Cavallini DB, Dalloul C, Shields CL, Jorge R. Retinal sensitivity and photoreceptor arrangement changes secondary to congenital simple hamartoma of retinal pigment epithelium. Int J Retina Vitreous 2019; 5:5. [PMID: 30675383 PMCID: PMC6332618 DOI: 10.1186/s40942-018-0154-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/31/2018] [Indexed: 12/05/2022] Open
Abstract
Background The congenital simple hamartoma of the retinal pigment epithelium is a benign lesion and previous observations with noninvasive imaging have detected potential photoreceptor abnormalities and retinal function interplay. Case presentation A 35-year-old woman was found to have an asymptomatic, solitary, circumscribed, pigmented lesion in her left eye. The patient underwent ophthalmic examination including multimodal evaluation with fluorescein angiography, near-infrared reflectance scanning laser ophthalmoscopy, blue autofluorescence, enhanced-depth imaging spectralis B-scan optical coherence tomography (EDI-SBOCT), en face OCT angiography (OCT-A) and microperimetry plus adaptive optics imaging. Ophthalmoscopic examination revealed a juxtafoveolar pigmented lesion with feeding retinal arteriole, consistent with congenital simple hamartoma of RPE. There was no macular edema, exudation, hemorrhage, traction or subretinal fluid. Multimodal imaging of the mass using fluorescein angiography revealed intra-lesion late staining, near-infrared reflectance imaging demonstrated intrinsic hyperreflectivity, short-wavelength autofluorescence and red-free filter photography revealed blocked signal, and SBOCT showed abrupt shadowing. On OCT-A, an exclusive ring-shaped vascular circuit with increased foveal avascular zone was noted. Adaptive optics revealed cell density arrangement and retinal sensitivity correlations on microperimetry. Conclusion These findings suggest that this hamartomatous lesion might cause specific cellular changes that impact retinal sensitivity response and potentially result from vasculature malnourishment to the outer retinal layers.
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Affiliation(s)
- M W Rodrigues
- 1Department of Ophthalmology, Ribeirão Preto School of Medicine, University of São Paulo, 3900, Bandeirantes Avenue, Ribeirão Prêto, SP 14049-900 Brazil
| | - D B Cavallini
- Department of Ophthalmology, São José do Rio Preto School of Medicine, São José do Rio Preto, Brazil
| | - C Dalloul
- Department of Ophthalmology, D'Olhos, São José do Rio Preto, Brazil
| | - C L Shields
- 4Ocular Oncology Service, Wills Eye Hospital, Philadelphia, USA
| | - R Jorge
- 1Department of Ophthalmology, Ribeirão Preto School of Medicine, University of São Paulo, 3900, Bandeirantes Avenue, Ribeirão Prêto, SP 14049-900 Brazil
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Qaysi S, Valente D, Vohnsen B. Differential detection of retinal directionality. BIOMEDICAL OPTICS EXPRESS 2018; 9:6318-6330. [PMID: 31065431 PMCID: PMC6490981 DOI: 10.1364/boe.9.006318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/11/2018] [Accepted: 11/12/2018] [Indexed: 05/06/2023]
Abstract
An adaptive optics fundus camera has been developed that uses simultaneous capture of multiple images via adjacent pupil sectors to provide directional sensitivity. In the chosen realization, a shallow refractive pyramid prism is used to subdivide backscattered light from the retina into four solid angles. Parafoveal fundus images have been captured for the eyes of three healthy subjects and directional scattering has been determined using horizontal and vertical differentials. The results for the photoreceptor cones, blood vessels, and the optic disc are discussed. In the case of cones, the observations are compared with numerical simulations based on a simplistic light-scattering model. Ultimately, the method may have diagnostic potential for diseases that perturb the microscopic structure of the retina.
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Affiliation(s)
- Salihah Qaysi
- Advanced Optical Imaging Group, School of Physics, University College Dublin, Dublin 4, Ireland
| | - Denise Valente
- Vision Science and Advanced Retinal Imaging Laboratory, University of California-Davis, Sacramento, CA, USA
| | - Brian Vohnsen
- Advanced Optical Imaging Group, School of Physics, University College Dublin, Dublin 4, Ireland
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Azimipour M, Zawadzki RJ, Gorczynska I, Migacz J, Werner JS, Jonnal RS. Intraframe motion correction for raster-scanned adaptive optics images using strip-based cross-correlation lag biases. PLoS One 2018; 13:e0206052. [PMID: 30359401 PMCID: PMC6201912 DOI: 10.1371/journal.pone.0206052] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 10/07/2018] [Indexed: 12/23/2022] Open
Abstract
In retinal raster imaging modalities, fixational eye movements manifest as image warp, where the relative positions of the beam and retina change during the acquisition of single frames. To remove warp artifacts, strip-based registration methods-in which fast-axis strips from target images are registered to a reference frame-have been applied in adaptive optics (AO) scanning light ophthalmoscopy (SLO) and optical coherence tomography (OCT). This approach has enabled object tracking and frame averaging, and methods have been described to automatically select reference frames with minimal motion. However, inconspicuous motion artifacts may persist in reference frames and propagate themselves throughout the processes of registration, tracking, and averaging. Here we test a previously proposed method for removing movement artifacts in reference frames, using biases in stripwise cross-correlation statistics. We applied the method to synthetic retinal images with simulated eye motion artifacts as well as real AO-SLO images of the cone mosaic and volumetric AO-OCT images, both affected by eye motion. In the case of synthetic images, the method was validated by direct comparison with motion-free versions of the images. In the case of real AO images, performance was validated by comparing the correlation of uncorrected images with that of corrected images, by quantifying the effect of motion artifacts on the image power spectra, and by qualitative examination of AO-OCT B-scans and en face projections. In all cases, the proposed method reduced motion artifacts and produced more faithful images of the retina.
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Affiliation(s)
- Mehdi Azimipour
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, CA, United States of America
| | - Robert J. Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, CA, United States of America
| | - Iwona Gorczynska
- Department of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
| | - Justin Migacz
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, CA, United States of America
| | - John S. Werner
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, CA, United States of America
| | - Ravi S. Jonnal
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, UC Davis Eye Center, Sacramento, CA, United States of America
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Efficacy Outcome Measures for Clinical Trials of USH2A Caused by the Common c.2299delG Mutation. Am J Ophthalmol 2018; 193:114-129. [PMID: 29953849 DOI: 10.1016/j.ajo.2018.06.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 06/12/2018] [Accepted: 06/19/2018] [Indexed: 12/27/2022]
Abstract
PURPOSE To determine the change in vision and retinal structure in patients with the common c.2299delG mutation in the USH2A gene in anticipation of clinical trials of therapy. DESIGN Retrospective observational case series. METHODS Eighteen patients, homozygotes or compound heterozygotes with the c.2299delG mutation in USH2A, were studied with regard to visual acuity, kinetic perimetry, dark- and light-adapted static perimetry, optical coherence tomography (OCT), and autofluorescence (AF) imaging. Serial data were available for at least half of the patients, depending on the parameter analyzed. RESULTS The kinetics of disease progression in this specific molecular form of USH2A differed between the measured parameters. Visual acuity could remain normal for decades. Kinetic and light-adapted static perimetry across the entire visual field had similar rates of decline that were slower than those of rod-based perimetry. Horizontal OCT scans through the macula showed that inner segment/outer segment line width had a similar rate of constriction as co-localized AF imaging and cone-based light-adapted sensitivity extent. The rate of constriction of rod-based sensitivity extent across this same region was twice as rapid as that of cones. CONCLUSIONS In patients with the c.2299delG mutation in USH2A, rod photoreceptors are the cells that express disease early and more aggressively than cones. Rod-based vision measurements in central or extracentral-peripheral retinal regions warrant monitoring in order to complete a clinical trial in a timely manner.
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Ha A, Kim YK, Jeoung JW, Park KH. Ellipsoid Zone Change According to Glaucoma Stage Advancement. Am J Ophthalmol 2018; 192:1-9. [PMID: 29750944 DOI: 10.1016/j.ajo.2018.04.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/24/2018] [Accepted: 04/28/2018] [Indexed: 01/01/2023]
Abstract
PURPOSE To compare retinal photoreceptor ellipsoid zone (EZ) intensity between normal eyes and those with different stages of glaucoma. DESIGN Retrospective cross-sectional study. METHODS The study included 37 normal, 38 preperimetric glaucoma, 39 mild-to-moderate glaucoma (visual field [VF] mean deviation [MD]: -7.7 ± 2.0 dB), and 36 severe glaucoma eyes (VF MD: -17.8 ± 3.2 dB). The subjects underwent high-resolution horizontal and vertical line scans through the fovea by spectral-domain optical coherence tomography (SD-OCT). Image processing software was employed to quantify the intensity of the first and second hyperreflective bands corresponding with the external limiting membrane (ELM) and EZ. In order to account for the brightness variation among scans, the relative EZ intensity as the ratio of the second to first reflective band (EZ/ELM) was determined. RESULTS The relative EZ intensity in severe glaucoma eyes was significantly lower than in mild-to-moderate glaucoma eyes (2.46 ± 0.38 vs 3.15 ± 0.43, P < .001); also, it was lower in mild-to-moderate than in preperimetric glaucoma eyes (3.15 ± 0.43 vs 3.86 ± 0.44, P < .001). However, the comparison between preperimetric glaucoma and normal eyes showed no significant difference (3.86 ± 0.44 vs 4.06 ± 0.40, P = .751). In 75 glaucomatous eyes with VF defect, there was a significant correlation between relative EZ intensity and VF MD (r = 0.83 and P < .001). CONCLUSIONS According to SD-OCT, relative EZ intensity reduction occurs in the mild-to-moderate and severe glaucoma stages. These findings suggest, at least provisionally, that in the course of glaucoma progression, mitochondrial changes in the inner segments of photoreceptors occur. Further investigation is warranted to evaluate the potential clinical significance of EZ intensity reduction in glaucoma.
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Affiliation(s)
- Ahnul Ha
- Department of Medicine, Seoul National University College of Medicine, Seoul, South Korea; and Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea
| | - Young Kook Kim
- Department of Medicine, Seoul National University College of Medicine, Seoul, South Korea; and Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea
| | - Jin Wook Jeoung
- Department of Medicine, Seoul National University College of Medicine, Seoul, South Korea; and Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea
| | - Ki Ho Park
- Department of Medicine, Seoul National University College of Medicine, Seoul, South Korea; and Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea.
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Sajdak BS, Bell BA, Lewis TR, Luna G, Cornwell GS, Fisher SK, Merriman DK, Carroll J. Assessment of Outer Retinal Remodeling in the Hibernating 13-Lined Ground Squirrel. Invest Ophthalmol Vis Sci 2018; 59:2538-2547. [PMID: 29847661 PMCID: PMC5967598 DOI: 10.1167/iovs.17-23120] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 04/20/2018] [Indexed: 12/25/2022] Open
Abstract
Purpose We examined outer retinal remodeling of the euthermic and torpid cone-dominant 13-lined ground squirrel (13-LGS) retina using optical coherence tomography (OCT) imaging and histology. Methods Retinas and corneas of living 13-LGSs were imaged during euthermic and torpid physiological states using OCT. Retinal layer thickness was measured at the visual streak from registered and averaged vertical B-scans. Following OCT, some retinas were collected immediately for postmortem histologic comparison using light microscopy, immunofluorescence, or transmission electron microscopy. Results Compared to OCT images from euthermic retinae, OCT images of torpid retinae revealed significantly thicker inner and outer nuclear layers, as well as increases in the distances between outer retinal reflectivity bands 1 and 2, and bands 3 and 4. A significant decrease in the distance between bands 2 and 3 also was seen, alongside significant thinning of the choriocapillaris and choroid. OCT image quality was reduced in torpid eyes, partly due to significant thickening of the corneal stroma during this state. Conclusions The torpid retina of the hibernating 13-LGS undergoes structural changes that can be detected by OCT imaging. Comparisons between in vivo OCT and ex vivo histomorphometry may offer insight to the origin of hyperreflective OCT bands within the outer retina of the cone-dominant 13-LGS.
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Affiliation(s)
- Benjamin S. Sajdak
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Brent A. Bell
- Cole Eye Institute/Ophthalmic Research, Cleveland Clinic, Cleveland, Ohio, United States
| | - Tylor R. Lewis
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Gabriel Luna
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States
| | - Grayson S. Cornwell
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States
| | - Steven K. Fisher
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, United States
| | - Dana K. Merriman
- Biology & Microbiology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, United States
| | - Joseph Carroll
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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Yiu G, Wang Z, Munevar C, Tieu E, Shibata B, Wong B, Cunefare D, Farsiu S, Roberts J, Thomasy SM. Comparison of chorioretinal layers in rhesus macaques using spectral-domain optical coherence tomography and high-resolution histological sections. Exp Eye Res 2018; 168:69-76. [PMID: 29352993 PMCID: PMC5826893 DOI: 10.1016/j.exer.2018.01.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 01/13/2018] [Accepted: 01/13/2018] [Indexed: 12/21/2022]
Abstract
Nonhuman primates are important preclinical models of retinal diseases because they uniquely possess a macula similar to humans. Ocular imaging technologies such as spectral-domain optical coherence tomography (SD-OCT) allow noninvasive, in vivo measurements of chorioretinal layers with near-histological resolution. However, the boundaries are based on differences in reflectivity, and detailed correlations with histological tissue layers have not been explored in rhesus macaques, which are widely used for biomedical research. Here, we compare the macular anatomy and thickness measurements of chorioretinal layers in rhesus macaque eyes using SD-OCT and high-resolution histological sections. Images were obtained from methylmethacrylate-embedded histological sections of 6 healthy adult rhesus macaques, and compared with SD-OCT images from 6 age-matched animals. Thicknesses of chorioretinal layers were measured across the central 3 mm macular region using custom semi-automated or manual software segmentation, and compared between the two modalities. We found that histological sections provide better distinction between the ganglion cell layer (GCL) and inner plexiform layer (IPL) than SD-OCT imaging. The first hyperreflective band between the external limiting membrane (ELM) and retinal pigment epithelium (RPE) appears wider on SD-OCT than the junction between photoreceptor inner and outer segments seen on histology. SD-OCT poorly distinguishes Henle nerve fibers from the outer nuclear layer (ONL), while histology correctly identifies these fibers as part of the outer plexiform layer (OPL). Overall, the GCL, inner nuclear layer (INL), and OPL are significantly thicker on histology, especially at the fovea; while the ONL, choriocapillaris (CC), and outer choroid (OC) are thicker on SD-OCT. Our results show that both SD-OCT and high-resolution histological sections allow reliable measurements of chorioretinal layers in rhesus macaques, with distinct advantages for different sublayers. These findings demonstrate the effects of tissue processing on chorioretinal anatomy, and provide normative values for chorioretinal thickness measurements on SD-OCT for future studies of disease models in these nonhuman primates.
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Affiliation(s)
- Glenn Yiu
- Department of Ophthalmology & Vision Science, University of California, Davis, Sacramento, CA, United States.
| | - Zhe Wang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Christian Munevar
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Eric Tieu
- Department of Ophthalmology & Vision Science, University of California, Davis, Sacramento, CA, United States
| | - Bradley Shibata
- Department of Cell Biology & Human Anatomy, University of California, Davis, Davis, CA, United States
| | - Brittany Wong
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - David Cunefare
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Jeffrey Roberts
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States; California National Primate Research Center, Davis, CA, United States
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
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