1
|
Hwang Y, Won J, Yaghy A, Takahashi H, Girgis JM, Lam K, Chen S, Moult EM, Ploner SB, Maier A, Waheed NK, Fujimoto JG. Retinal blood flow speed quantification at the capillary level using temporal autocorrelation fitting OCTA [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:2658-2677. [PMID: 37342704 PMCID: PMC10278638 DOI: 10.1364/boe.488103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/23/2023] [Accepted: 04/29/2023] [Indexed: 06/23/2023]
Abstract
Optical coherence tomography angiography (OCTA) can visualize vasculature structures, but provides limited information about blood flow speed. Here, we present a second generation variable interscan time analysis (VISTA) OCTA, which evaluates a quantitative surrogate marker for blood flow speed in vasculature. At the capillary level, spatially compiled OCTA and a simple temporal autocorrelation model, ρ(τ) = exp(-ατ), were used to evaluate a temporal autocorrelation decay constant, α, as the blood flow speed marker. A 600 kHz A-scan rate swept-source OCT prototype instrument provides short interscan time OCTA and fine A-scan spacing acquisition, while maintaining multi mm2 field of views for human retinal imaging. We demonstrate the cardiac pulsatility and assess repeatability of α measured with VISTA. We show different α for different retinal capillary plexuses in healthy eyes and present representative VISTA OCTA in eyes with diabetic retinopathy.
Collapse
Affiliation(s)
- Yunchan Hwang
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jungeun Won
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Antonio Yaghy
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - Hiroyuki Takahashi
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | | | - Kenneth Lam
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - Siyu Chen
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Eric M. Moult
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stefan B. Ploner
- Pattern Recognition Lab, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Maier
- Pattern Recognition Lab, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nadia K. Waheed
- New England Eye Center, Tufts Medical Center, Boston, MA 02116, USA
| | - James G. Fujimoto
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| |
Collapse
|
2
|
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
|
3
|
Ashimatey BS, Zhou X, Chu Z, Alluwimi M, Wang RK, Kashani AH. Variability of Vascular Reactivity in the Retina and Choriocapillaris to Oxygen and Carbon Dioxide Using Optical Coherence Tomography Angiography. Invest Ophthalmol Vis Sci 2023; 64:9. [PMID: 36745450 PMCID: PMC9910388 DOI: 10.1167/iovs.64.2.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Purpose To investigate the regional and layer-specific vascular reactivity of the healthy human retina and choriocapillaris to changes in systemic carbon dioxide or oxygen. Methods High-resolution 3 × 3-mm2 optical coherence tomography angiography (OCTA) images were acquired from the central macula, temporal macula, and peripapillary retina while participants were exposed to three gas breathing conditions-room air, 5%CO2, and 100% O2. OCTA from all three regions were extracted and the apparent skeletonized vessel density (VSD) was assessed. The mean flow deficit sizes (MFDSs) of the choriocapillaris were also assessed. Repeated-measures analysis of variance was used to compare the ratio of intrasubject VSD change induced by the gas conditions from baseline in the superficial retinal layer (SRL) and deep retinal layer (DRL) for each retinal region independently, as well as the MFDS of the choriocapillaris. We also compared the vessel reactivity between the retinal capillaries and the choriocapillaris. Results The cumulative intrasubject response to the gas conditions differed significantly among regions of the SRL (F(2, 7) = 28.22, P < 0.001), with the temporal macula showing the largest response (15%) compared to the macula (8%) and radial peripapillary capillaries (7%). A similar trend was found in the DRL. The choriocapillaris reactivity was similar between the macula (5.8%) and temporal macula (5.6%). There was also a significant heterogeneity in the layer-specific gas responses, with the DRL showing the largest response (28.2%) and the choriocapillaris showing the smallest response (2.8%). Conclusions Capillary reactivity to changes in inhaled O2 and CO2 is spatially heterogeneous across the retina but not choriocapillaris.
Collapse
Affiliation(s)
- Bright S. Ashimatey
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Xiao Zhou
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Muhammed Alluwimi
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States,Department of Ophthalmology, University of Washington Seattle, Washington, United States
| | - Amir H. Kashani
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States
| |
Collapse
|
4
|
Morgan JIW, Chui TYP, Grieve K. Twenty-five years of clinical applications using adaptive optics ophthalmoscopy [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:387-428. [PMID: 36698659 PMCID: PMC9841996 DOI: 10.1364/boe.472274] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/22/2022] [Accepted: 11/27/2022] [Indexed: 05/02/2023]
Abstract
Twenty-five years ago, adaptive optics (AO) was combined with fundus photography, thereby initiating a new era in the field of ophthalmic imaging. Since that time, clinical applications of AO ophthalmoscopy to investigate visual system structure and function in both health and disease abound. To date, AO ophthalmoscopy has enabled visualization of most cell types in the retina, offered insight into retinal and systemic disease pathogenesis, and been integrated into clinical trials. This article reviews clinical applications of AO ophthalmoscopy and addresses remaining challenges for AO ophthalmoscopy to become fully integrated into standard ophthalmic care.
Collapse
Affiliation(s)
- Jessica I. W. Morgan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Contributed equally
| | - Toco Y. P. Chui
- Department of Ophthalmology, The New York Eye and Ear Infirmary of Mount Sinai, New York, NY 10003, USA
- Contributed equally
| | - 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
- Contributed equally
| |
Collapse
|
5
|
Blanco-Hernández DMR, Somilleda-Ventura SA, Chávez-Herrera R, Colas-Calvere MG, Lima-Gómez V. Compensatory contribution of retinal larger vessels to perfusion density in diabetics without retinopathy. Sci Rep 2022; 12:329. [PMID: 35013324 PMCID: PMC8748763 DOI: 10.1038/s41598-021-02554-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/10/2021] [Indexed: 11/25/2022] Open
Abstract
Vessel and perfusion densities may decrease before diabetic retinopathy appears; it is unknown whether these changes affect the contribution of vessel density to perfusion density. This was a non-experimental, comparative, prospective, cross-sectional study in non-diabetic subjects (group 1) and diabetics without retinopathy (group 2). Vessel and perfusion densities in the superficial capillary plexus were compared between groups at the center, inner, and full regions and by field (superior, temporal, inferior, nasal) using optical coherence tomography angiography. Coefficients of determination (R2) between vessel and perfusion densities were calculated to find the contribution of larger retinal vessels to perfusion density. Percent differences were used to evaluate the contribution of these vessels to perfusion density in a regression model. There were 62 participants, 31 eyes by group; vessel and perfusion densities as well as the coefficients of determination between them were lower in group 2, especially in the nasal field (R2 0.85 vs. 0.71), which showed a higher contribution of larger retinal vessels to perfusion density. The regression model adjusted to a quadratic equation. In diabetics without retinopathy the contribution of vessel density to perfusion density may decrease; a low vessel density may increase the contribution of larger retinal vessels to perfusion density.
Collapse
Affiliation(s)
| | | | - Rebeca Chávez-Herrera
- Medicine School, Universidad Autonoma de Ciudad Juarez, 32315, Ciudad Juarez, Mexico
| | | | - Virgilio Lima-Gómez
- Ophthalmology Service, Hospital Juarez de Mexico, 07760, Mexico City, Mexico.
| |
Collapse
|
6
|
Warner RL, Gast TJ, Sapoznik KA, Carmichael-Martins A, Burns SA. Measuring Temporal and Spatial Variability of Red Blood Cell Velocity in Human Retinal Vessels. Invest Ophthalmol Vis Sci 2021; 62:29. [PMID: 34846516 PMCID: PMC8648047 DOI: 10.1167/iovs.62.14.29] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The retinal circulation regulates blood flow through various internal and external factors; however, it is unclear how locally these factors act within the retinal microcirculation. We measured the temporal and spatial variability of blood velocity in small retinal vessels using a dual-beam adaptive optics scanning laser ophthalmoscope. Methods In young healthy subjects (n = 3), temporal blood velocity variability was measured in a local vascular region consisting of an arteriole, capillary, and venule repeatedly over 2 days. Data consisted of 10 imaging periods separated into two sessions: (1) five 6-minute image acquisition periods with 30-minute breaks, and (2) five 6-minute image acquisition periods with 10-minute breaks. In another group of young healthy subjects (n = 5), spatial distribution of velocity variability was measured by imaging three capillary segments during three 2-minute conditions: (1) baseline imaging condition (no flicker), (2) full-field flicker, and (3) no flicker condition again. Results Blood velocities were measurable in all subjects with a reliability of about 2%. The coefficient of variation (CV) was used as an estimate of the physiological variability of each vessel. Over 2 days, the average CV in arterioles was 7% (±2%); in capillaries, it was 19% (±6%); and, in venules, it was 8% (±2%). During flicker stimulation, the average capillary CV was 16% during baseline, 15% during flicker stimulation, and 18% after flicker stimulation. Conclusions Capillaries in the human retina exhibit spatial and temporal variations in blood velocity. This inherent variation in blood velocity places limits on studying the vascular regulation of individual capillaries, and the study presented here serves as a foundation for future endeavors.
Collapse
Affiliation(s)
- Raymond L Warner
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Thomas J Gast
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Kaitlyn A Sapoznik
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | | | - Stephen A Burns
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| |
Collapse
|
7
|
Abstract
Advances in retinal imaging are enabling researchers and clinicians to make precise noninvasive measurements of the retinal vasculature in vivo. This includes measurements of capillary blood flow, the regulation of blood flow, and the delivery of oxygen, as well as mapping of perfused blood vessels. These advances promise to revolutionize our understanding of vascular regulation, as well as the management of retinal vascular diseases. This review provides an overview of imaging and optical measurements of the function and structure of the ocular vasculature. We include general characteristics of vascular systems with an emphasis on the eye and its unique status. The functions of vascular systems are discussed, along with physical principles governing flow and its regulation. Vascular measurement techniques based on reflectance and absorption are briefly introduced, emphasizing ways of generating contrast. One of the prime ways to enhance contrast within vessels is to use techniques sensitive to the motion of cells, allowing precise measurements of perfusion and blood velocity. Finally, we provide a brief introduction to retinal vascular diseases.
Collapse
Affiliation(s)
- Stephen A Burns
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
| | - Ann E Elsner
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
| | - Thomas J Gast
- Indiana University School of Optometry, Bloomington, Indiana 47405, USA; , ,
| |
Collapse
|
8
|
Lal A, Dave N, Gibbs OJ, Barry MAT, Sood A, Mitchell P, Thiagalingam A. Effect of ECG-gating Retinal Photographs on Retinal Vessel Caliber Measurements in Subjects with and without Type 2 Diabetes. Curr Eye Res 2021; 46:1742-1750. [PMID: 33960254 DOI: 10.1080/02713683.2021.1927112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Purpose/Aim of this study: Retinal vessel caliber is an independent risk marker of cardiovascular disease risk. However, variable mechanical delays in capturing retinal photographs and cardiac cycle-induced retinal vascular changes have been shown to reduce the accuracy of retinal vessel caliber measurements, but this has only ever been investigated in healthy subjects. This cross-sectional study is the first study to investigate this issue in type 2 diabetes. The aim of this study was to determine whether ECG-gating retinal photographs reduce the variability in retinal arteriolar and venular caliber measurements in controls and type 2 diabetes.Materials and Methods: Fifteen controls and 15 patients with type 2 diabetes were arbitrarily recruited from Westmead Hospital, Sydney, Australia. A mydriatic fundoscope connected to our novel ECG synchronization unit captured 10 ECG-gated (at the QRS) and 10 ungated digital retinal photographs of the left eye in a randomized fashion, blinded to study participants. Two independent reviewers used an in-house semi-automated software to grade single cross-sectional vessel diameters across photographs, between 900 and 1800 microns from the optic disc edge. The coefficient of variation compared caliber variability between retinal arterioles and venules.Results: Our ECG synchronization unit reported the smallest time delay (33.1 ± 48.4 ms) in image capture known in the literature. All 30 participants demonstrated a higher reduction in retinal arteriolar (ungated: 1.02, 95%CI 0.88-1.17% vs ECG-gated: 0.39, 95%CI 0.29-0.49%, p < .0001) than venular (ungated 0.62, 95%CI 0.53-0.73% vs ECG-gated: 0.26, 95%CI 0.19-0.35%, p < .0001) coefficient of variation by ECG-gating photographs. Intra-observer repeatability and inter-observer reproducibility analysis reported high interclass correlation coefficients ranging from 0.80 to 0.86 and 0.80 to 0.93 respectively.Conclusion: ECG-gating photographs at the QRS are recommended for retinal vessel caliber analysis in controls and patients with type 2 diabetes as they refine measurements.
Collapse
Affiliation(s)
- Anchal Lal
- Department of Cardiology, Westmead Hospital, Sydney, Australia.,Sydney Medical School, The University of Sydney, Sydney, Australia.,Centre for Vision Research, The Westmead Institute for Medical Research Hospital, Sydney, Australia
| | - Neha Dave
- School of Medicine and Public Health, University of Newcastle, Callaghan, Australia
| | - Oliver J Gibbs
- Department of Cardiology, Westmead Hospital, Sydney, Australia.,Sydney Medical School, The University of Sydney, Sydney, Australia
| | | | - Annika Sood
- Department of Cardiology, Westmead Hospital, Sydney, Australia
| | - Paul Mitchell
- Sydney Medical School, The University of Sydney, Sydney, Australia.,Centre for Vision Research, The Westmead Institute for Medical Research Hospital, Sydney, Australia
| | - Aravinda Thiagalingam
- Department of Cardiology, Westmead Hospital, Sydney, Australia.,Sydney Medical School, The University of Sydney, Sydney, Australia
| |
Collapse
|
9
|
Luo T, Warner RL, Sapoznik KA, Walker BR, Burns SA. Template free eye motion correction for scanning systems. OPTICS LETTERS 2021; 46:753-756. [PMID: 33577506 PMCID: PMC8447858 DOI: 10.1364/ol.415285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 12/31/2020] [Indexed: 05/18/2023]
Abstract
Scanning imaging systems are susceptible to image warping in the presence of target motion occurring within the time required to acquire an individual image frame. In this Letter, we introduce the use of a dual raster scanning approach to correct for motion distortion without the need for prior knowledge of the undistorted image. In the dual scanning approach, the target is imaged simultaneously with two imaging beams from the same imaging system. The two imaging beams share a common pupil but have a spatial shift between the beams on the imaging plane. The spatial shift can be used to measure high speed events, because it measures an identical region at two different times within the time required for acquisition of a single frame. In addition, it provides accurate spatial information, since two different regions on the target are imaged simultaneously, providing an undistorted estimate of the spatial relation between regions. These spatial and temporal relations accurately measure target motion. Data from adaptive optics scanning laser ophthalmoscope (AOSLO) imaging of the human retina are used to demonstrate this technique. We apply the technique to correct the shearing of retinal images produced by eye motion. Three control subjects were measured while imaging different retinal layers and retinal locations to qualify the effectiveness of the algorithm. Since the time shift between channels is readily adjustable, this method can be tuned to match different imaging situations. The major requirement is the need to separate the two images; in our case, we used different near infrared spectral regions and dichroic filters.
Collapse
Affiliation(s)
- Ting Luo
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Raymond L. Warner
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Kaitlyn A Sapoznik
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Brittany R. Walker
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Stephen A. Burns
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| |
Collapse
|