1
|
Mautuit T, Cunnac P, Truffer F, Anjos A, Dufrane R, Maître G, Geiser M, Chiquet C. Absolute retinal blood flow in healthy eyes and in eyes with retinal vein occlusion. Microvasc Res 2024; 152:104648. [PMID: 38123065 DOI: 10.1016/j.mvr.2023.104648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/30/2023] [Accepted: 12/13/2023] [Indexed: 12/23/2023]
Abstract
PURPOSE To measure non-invasively retinal venous blood flow (RBF) in healthy subjects and patients with retinal venous occlusion (RVO). METHODS The prototype named AO-LDV (Adaptive Optics Laser Doppler Velocimeter), which combines a new absolute laser Doppler velocimeter with an adaptive optics fundus camera (rtx1, Imagine Eyes®, Orsay, France), was studied for the measurement of absolute RBF as a function of retinal vessel diameters and simultaneous measurement of red blood cell velocity. RBF was measured in healthy subjects (n = 15) and patients with retinal venous occlusion (RVO, n = 6). We also evaluated two softwares for the measurement of retinal vessel diameters: software 1 (automatic vessel detection, profile analysis) and software 2 (based on the use of deep neural networks for semantic segmentation of vessels, using a M2u-Net architecture). RESULTS Software 2 provided a higher rate of automatic retinal vessel measurement (99.5 % of 12,320 AO images) than software 1 (64.9 %) and wider measurements (75.5 ± 15.7 μm vs 70.9 ± 19.8 μm, p < 0.001). For healthy subjects (n = 15), all the retinal veins in one eye were measured to obtain the total RBF. In healthy subjects, the total RBF was 37.8 ± 6.8 μl/min. There was a significant linear correlation between retinal vessel diameter and maximal velocity (slope = 0.1016; p < 0.001; r2 = 0.8597) and a significant power curve correlation between retinal vessel diameter and blood flow (3.63 × 10-5 × D2.54; p < 0.001; r2 = 0.7287). No significant relationship was found between total RBF and systolic and diastolic blood pressure, ocular perfusion pressure, heart rate, or hematocrit. For RVO patients (n = 6), a significant decrease in RBF was noted in occluded veins (3.51 ± 2.25 μl/min) compared with the contralateral healthy eye (11.07 ± 4.53 μl/min). For occluded vessels, the slope between diameter and velocity was 0.0195 (p < 0.001; r2 = 0.6068) and the relation between diameter and flow was Q = 9.91 × 10-6 × D2.41 (p < 0.01; r2 = 0.2526). CONCLUSION This AO-LDV prototype offers new opportunity to study RBF in humans and to evaluate treatment in retinal vein diseases.
Collapse
Affiliation(s)
- Thibaud Mautuit
- Department of Ophthalmology, University Hospital of Grenoble-Alpes, France; Grenoble-Alpes University, HP2 Laboratory, INSERM U1042, Grenoble, France
| | - Pierre Cunnac
- Department of Ophthalmology, University Hospital of Grenoble-Alpes, France; Grenoble-Alpes University, HP2 Laboratory, INSERM U1042, Grenoble, France
| | | | - André Anjos
- Idiap Research Institute, Martigny, Switzerland
| | - Rebecca Dufrane
- Department of Ophthalmology, University Hospital of Grenoble-Alpes, France; Grenoble-Alpes University, HP2 Laboratory, INSERM U1042, Grenoble, France
| | | | | | - Christophe Chiquet
- Department of Ophthalmology, University Hospital of Grenoble-Alpes, France; Grenoble-Alpes University, HP2 Laboratory, INSERM U1042, Grenoble, France.
| |
Collapse
|
2
|
Chen N, Zhu Z, Yang W, Wang Q. Progress in clinical research and applications of retinal vessel quantification technology based on fundus imaging. Front Bioeng Biotechnol 2024; 12:1329263. [PMID: 38456011 PMCID: PMC10917897 DOI: 10.3389/fbioe.2024.1329263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 02/12/2024] [Indexed: 03/09/2024] Open
Abstract
Retinal blood vessels are the only directly observed blood vessels in the body; changes in them can help effective assess the occurrence and development of ocular and systemic diseases. The specificity and efficiency of retinal vessel quantification technology has improved with the advancement of retinal imaging technologies and artificial intelligence (AI) algorithms; it has garnered attention in clinical research and applications for the diagnosis and treatment of common eye and related systemic diseases. A few articles have reviewed this topic; however, a summary of recent research progress in the field is still needed. This article aimed to provide a comprehensive review of the research and applications of retinal vessel quantification technology in ocular and systemic diseases, which could update clinicians and researchers on the recent progress in this field.
Collapse
Affiliation(s)
- Naimei Chen
- Department of Ophthalmology, Huaian Hospital of Huaian City, Huaian, China
| | - Zhentao Zhu
- Department of Ophthalmology, Huaian Hospital of Huaian City, Huaian, China
| | - Weihua Yang
- Department of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, China
| | - Qiang Wang
- Department of Ophthalmology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, China
| |
Collapse
|
3
|
Simó R, Franch-Nadal J, Vlacho B, Real J, Amado E, Flores J, Mata-Cases M, Ortega E, Rigla M, Vallés JA, Hernández C, Mauricio D. Rapid Reduction of HbA1c and Early Worsening of Diabetic Retinopathy: A Real-world Population-Based Study in Subjects With Type 2 Diabetes. Diabetes Care 2023; 46:1633-1639. [PMID: 37428631 DOI: 10.2337/dc22-2521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 06/03/2023] [Indexed: 07/12/2023]
Abstract
OBJECTIVE Early worsening of diabetic retinopathy (EWDR) due to the rapid decrease of blood glucose levels is a concern in diabetes treatment. The aim of the current study is to evaluate whether this is an important issue in subjects with type 2 diabetes with mild or moderate nonproliferative DR (NPDR), who represent the vast majority of subjects with DR attended in primary care. RESEARCH DESIGN AND METHODS This is a retrospective nested case-control study of subjects with type 2 diabetes and previous mild or moderate NPDR. Using the SIDIAP ("Sistema d'informació pel Desenvolupament de la Recerca a Atenció Primària") database, we selected 1,150 individuals with EWDR and 1,150 matched control subjects (DR without EWDR). The main variable analyzed was the magnitude of the reduction of HbA1c in the previous 12 months. The reduction of HbA1c was categorized as rapid (>1.5% reduction in <12 months) or very rapid (>2% in <6 months). RESULTS We did not find any significant difference in HbA1c reduction between case and control subjects (0.13 ± 1.21 vs. 0.21 ± 1.18; P = 0.12). HbA1c reduction did not show significant association with worsening of DR, neither in the unadjusted analyses nor in adjusted statistical models that included the main confounding variables: duration of diabetes, baseline HbA1c, presence of hypertension, and antidiabetic drugs. In addition, when stratification by baseline HbA1c was performed, we did not find that those patients with higher levels of HbA1c presented a higher risk to EWDR. CONCLUSIONS Our results suggest that the rapid reduction of HbA1c is not associated with progression of mild or moderate NPDR.
Collapse
Affiliation(s)
- Rafael Simó
- Vall d'Hebron Research Institute, Vall d'Hebron University Hospital, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Department of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Josep Franch-Nadal
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Grup de Diabetis d'Atenció Primària (DAP-Cat), Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
- Primary Health Care Center Raval Sud, Gerència d'Àmbit d'Atenció Primària Barcelona Ciutat, Institut Català de la Salut, Barcelona, Spain
| | - Bogdan Vlacho
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Grup de Diabetis d'Atenció Primària (DAP-Cat), Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
- Institut de Recerca Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Jordi Real
- Grup de Diabetis d'Atenció Primària (DAP-Cat), Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
| | - Ester Amado
- Gerència del Medicament, Institut Català de la Salut, Gerència d'Atenció Primaria, Barcelona, Spain
| | - Juana Flores
- Department of Endocrinology and Nutrition, Hospital Universitari del Mar, Barcelona, Spain
| | - Manel Mata-Cases
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Grup de Diabetis d'Atenció Primària (DAP-Cat), Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
- Gerència d'Àmbit d'Atenció Primària Barcelona Ciutat, Institut Català de la Salut, Primary Health Care Center La Mina, Sant Adrià de Besòs, Spain
| | - Emilio Ortega
- Department of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Endocrinology and Nutrition, Institut d'Investigacions Biomèdiques August Pi i Suñer, Hospital Clínic, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Mercedes Rigla
- Department of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Endocrinology and Nutrition, Hospital Universitari Parc Taulí, Institut d'Investigació I Innovació Parc Tauli, Sabadell, Spain
| | - Joan-Anton Vallés
- Gerència del Medicament, Institut Català de la Salut, Gerència d'Atenció Primaria, Barcelona, Spain
| | - Cristina Hernández
- Vall d'Hebron Research Institute, Vall d'Hebron University Hospital, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Department of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Didac Mauricio
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Grup de Diabetis d'Atenció Primària (DAP-Cat), Unitat de Suport a la Recerca Barcelona, Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina, Barcelona, Spain
- Department of Endocrinology and Nutrition, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Department of Medicine, University of Vic - Central University of Catalonia, Vic, Spain
| |
Collapse
|
4
|
Abbasnejad A, Tomkins-Netzer O, Winter A, Friedman A, Cruess A, Serlin Y, Levy J. A fluorescein angiography-based computer-aided algorithm for assessing the retinal vasculature in diabetic retinopathy. Eye (Lond) 2023; 37:1293-1301. [PMID: 35643792 PMCID: PMC10170131 DOI: 10.1038/s41433-022-02120-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 04/24/2022] [Accepted: 05/20/2022] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVE To present a fluorescein angiography (FA)‒based computer algorithm for quantifying retinal blood flow, perfusion, and permeability, in patients with diabetic retinopathy (DR). Secondary objectives were to quantitatively assess treatment efficacy following panretinal photocoagulation (PRP) and define thresholds for pathology based on a new retinovascular function (RVF) score for quantifying disease severity. METHODS FA images of 65 subjects (58 patients and 7 healthy volunteers) were included. Dye intensity kinetics were derived using pixel-wise linear regression as a measure of retinal blood flow, perfusion, and permeability. Maps corresponding to each measure were then generated for each subject and segmented further using an ETDRS grid. Non-parametric statistical analyses were performed between all ETDRS subfields. For 16 patients, the effect of PRP was measured using the same parameters, and an amalgam of RVF was used to create an RVF index. For ten post-treatment patients, the change in FA-derived data was compared to the macular thickness measured using optical coherence tomography. RESULTS Compared to healthy controls, patients had significantly lower retinal and regional perfusion and flow, as well as higher retinal permeability (p < 0.05). Moreover, retinal flow was inversely correlated with permeability (R = -0.41; p < 0.0001). PRP significantly reduced retinal permeability (p < 0.05). The earliest marker of DR was reduced retinal blood flow, followed by increased permeability. FA-based RVF index was a more sensitive indicator of treatment efficacy than macular thickness. CONCLUSIONS Our algorithm can be used to quantify retinovascular function, providing an earlier diagnosis and an objective characterisation of disease state, disease progression, and response to treatment.
Collapse
Affiliation(s)
- Amir Abbasnejad
- Faculty of Computer Science, Dalhousie University, Halifax, NS, Canada
- Emagix, Inc., Halifax, NS, Canada
| | - Oren Tomkins-Netzer
- Department of Ophthalmology, Faculty of Medicine, Carmel Medical Center, Technion, Haifa, Israel
| | - Aaron Winter
- Department of Ophthalmology, QEII Hospital, Dalhousie University, Halifax, NS, Canada
| | - Alon Friedman
- Emagix, Inc., Halifax, NS, Canada
- Departments of Medical Neuroscience and Pediatrics, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Alan Cruess
- Department of Ophthalmology, QEII Hospital, Dalhousie University, Halifax, NS, Canada
| | - Yonatan Serlin
- Neurology Residency Training Program and Department of Neurology and Neurosurgery, Jewish General Hospital (J.M.), McGill University, Montreal, QC, Canada
| | - Jaime Levy
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
| |
Collapse
|
5
|
Liu R, Wang X, Hoshi S, Zhang Y. High-speed measurement of retinal arterial blood flow in the living human eye with adaptive optics ophthalmoscopy. OPTICS LETTERS 2023; 48:1994-1997. [PMID: 37058625 PMCID: PMC11185870 DOI: 10.1364/ol.480896] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
We present a technique to measure the rapid blood velocity in large retinal vessels with high spatiotemporal resolution. Red blood cell motion traces in the vessels were non-invasively imaged using an adaptive optics near-confocal scanning ophthalmoscope at a frame rate of 200 fps. We developed software to measure blood velocity automatically. We demonstrated the ability to measure the spatiotemporal profiles of the pulsatile blood flow with a maximum velocity of 95-156 mm/s in retinal arterioles with a diameter >100 µm. High-speed and high-resolution imaging increased the dynamic range, enhanced sensitivity, and improved the accuracy when studying retinal hemodynamics.
Collapse
Affiliation(s)
- Ruixue Liu
- Doheny Eye Institute, 150 N Orange Grove Blvd, Pasadena, CA 91103
| | - Xiaolin Wang
- Doheny Eye Institute, 150 N Orange Grove Blvd, Pasadena, CA 91103
| | - Sujin Hoshi
- Doheny Eye Institute, 150 N Orange Grove Blvd, Pasadena, CA 91103
- Department of Ophthalmology, University of California - Los Angeles, 100 Stein Plaza Driveway, Los Angeles, CA 90024
- Department of Ophthalmology, University of Tsukuba, Ibaraki, Japan
| | - Yuhua Zhang
- Doheny Eye Institute, 150 N Orange Grove Blvd, Pasadena, CA 91103
- Department of Ophthalmology, University of California - Los Angeles, 100 Stein Plaza Driveway, Los Angeles, CA 90024
| |
Collapse
|
6
|
Bhattacharya S, M KR, Priyadarshani J, Ganguly R, Chakraborty S. Targeting Magnetic Nanoparticles in Physiologically Mimicking Tissue Microenvironment. ACS APPLIED MATERIALS & INTERFACES 2022; 14:31689-31701. [PMID: 35786842 DOI: 10.1021/acsami.2c07246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Magnetic nanoparticles as drug carriers, despite showing immense promises in preclinical trials, have remained to be only of limited use in real therapeutic practice primarily due to unresolved anomalies concerning their grossly contrasting controllability and variability in performance in artificial test benches as compared to human tissues. To circumvent the deficits of reported in vitro drug testing platforms that deviate significantly from the physiological features of the living systems and result in this puzzling contrast, here, we fabricate a biomimetic microvasculature in a flexible tissue phantom and demonstrate distinctive mechanisms of magnetic-field-assisted controllable penetration of biocompatible iron oxide nanoparticles across the same, exclusively modulated by tissue deformability, which has by far remained unraveled. Our experiments deciphering the transport of magnetic nanoparticles in a blood analogue medium unveil a decisive interplay of the flexibility of the microvascular pathways, magnetic pull, and viscous friction toward orchestrating the optimal vascular penetration and targeting efficacy of the nanoparticles in colorectal tissue-mimicking bioengineered media. Subsequent studies with biological cells confirm the viability of using localized magnetic forces for aiding nanoparticle penetration within cancerous lesions. We establish nontrivially favorable conditions to induce a threshold force for vascular rupture and eventual target of the nanoparticles toward the desired extracellular site. These findings appear to be critical in converging the success of in vitro trials toward patient-specific targeted therapies depending on personalized vascular properties obtained from medical imaging data.
Collapse
Affiliation(s)
- Soumya Bhattacharya
- Department of Mechanical Engineering, IIT-Kharagpur, Kharagpur 721302, India
| | - Kiran Raj M
- Advanced Technology Development Center, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | | | - Ranjan Ganguly
- Department of Power Engineering, Jadavpur University, LB-8, Sector-III, Salt Lake, Kolkata 700106, India
| | - Suman Chakraborty
- Department of Mechanical Engineering, IIT-Kharagpur, Kharagpur 721302, India
| |
Collapse
|
7
|
Yao T, He Y, Huang L, Chen J, Zhang Z, Yang W, Gao X, Dan Y, Huai S, Ou S, He Y. Quantitative vessel density analysis of macular and peripapillary areas by optical coherence tomography angiography in adults with primary nephrotic syndrome. Microvasc Res 2022; 144:104407. [PMID: 35863428 DOI: 10.1016/j.mvr.2022.104407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/17/2022] [Accepted: 07/13/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE To compare the microvascular parameters of macular and peripapillary areas in adults with primary nephrotic syndrome (PNS) and healthy controls (HCs). METHODS In this cross-sectional study, optical coherence tomography angiography (OCTA) was used to evaluate the changes in retinal microvascular in 37 adult patients with PNS and 30 HCs in this study. All subjects underwent OCTA for measuring vascular density (VD), perfusion density (PD), and foveal avascular zone (FAZ) in the superficial capillary plexus (SCP) and optical coherence tomography (OCT) for measuring central macular thickness (CMT) and retinal nerve fiber layer (RNFL) thickness. The following clinical data of the PNS group were collected: hemoglobin, platelet, total protein, albumin, prealbumin, creatinine, urea nitrogen, glomerular filtration rate, blood lipid, urinary protein, urine microalbumin, urine microalbumin/creatinine, 24-h urine volume, and 24-h urine protein quantification. The OCTA data were compared between patients with PNS and HCs, and the correlation between the OCTA data and clinical data was analyzed in the PNS group. RESULTS VD and PD in the macular area of the PNS group were significantly lower than those in the HC group (VD: 17.025 ± 2.229 vs. 18.290 ± 0.721, P = 0.001; PD: 0.417 ± 0.058 vs. 0.450 ± 0.019, P = 0.003). No significant differences in the FAZ area and perioptic disc microvascular parameters were observed between the two groups, and patients in the PNS group showed consistent changes in the left and right eyes. VD and PD in the central macular area were positively correlated with plasma prealbumin level (VD: ρ = 0.541, P = 0.001; PD: ρ = 0.562, P < 0.001) and negatively correlated with urinary protein level (VD: ρ = -0.579, P < 0.001; PD: ρ = -0.596, P < 0.001). CONCLUSIONS In adult patients with PNS, the decrease in VD and PD was mainly occurred in the macular area. Partly vascular density of the macular area was positively correlated with plasma prealbumin level and negatively correlated with urinary protein level. OCTA provides a convenient, non-invasive and effective method for evaluating and monitoring retinal microcirculation damage in patients with PNS.
Collapse
Affiliation(s)
- Tianyu Yao
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China; Department of Ophthalmology, Changning County Hospital of Traditional Chinese Medicine, Yibin, PR China
| | - Yemei He
- Department of Nephrology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China; Sichuan Clinical Research Center for Nephropathy, Luzhou, Sichuan 646000, PR China
| | - Li Huang
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China
| | - Jie Chen
- Department of Rheumatology and Immunology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China
| | - Zhiru Zhang
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China
| | - Wei Yang
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China
| | | | - Yujiao Dan
- Department of Ophthalmology, The People's Hospital of Leshan, PR China
| | - Shixiang Huai
- Department of Ophthalmology, Changning County Hospital of Traditional Chinese Medicine, Yibin, PR China
| | - Santao Ou
- Department of Nephrology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China; Sichuan Clinical Research Center for Nephropathy, Luzhou, Sichuan 646000, PR China.
| | - Yue He
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, PR China.
| |
Collapse
|
8
|
Düzgün E, Şahin T, Yeşiltaş SK, Alkan AA, Dikmen NT. Ozone-induced retinal vascular reactivity as assessed by optical coherence tomography angiography. Photodiagnosis Photodyn Ther 2022; 39:102957. [PMID: 35690324 DOI: 10.1016/j.pdpdt.2022.102957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/18/2022] [Accepted: 06/07/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND This study aimed to investigate the retinal vascular reactivity (RVR) of the macular and peripapillary capillary network in response to ozonated autohemotherapy (AHT) using optical coherence tomography angiography (OCTA). METHODS This was a single-centre prospective study. All participants that were planned to have a combination of major and minor ozone AHT underwent a complete ocular examination and OCTA imaging before and after the ozone AHT. Foveal avascular zone (FAZ) metrics and vessel density (VD) of superficial (SCP), deep capillary plexus (DCP), and radial peripapillary capillary (RPC) plexus were assessed using the built-in software. RESULTS A total of 40 right eyes of 40 individuals were included. No significant differences were observed for the mean values of the FAZ metrics and choriocapillaris flow area following ozone AHT compared with baseline values (p > 0.05). The mean whole VD of SCP and DCP was 47.80 ± 2.18% and 53.09 ± 3.00% before treatment, which decreased to 47.68 ± 2.7% and 52.38 ± 3.07% after treatment (p = 0.660 and p = 0.097, respectively). No significant differences were observed in the vascular densities of both SCP and DCP in any quadrant (p > 0.05). The RPC density did not show significant alterations compared with baseline values, except the inferior-hemi region. The VD in the inferior-hemi peripapillary quadrant was significantly increased after ozone AHT (p = 0.034). CONCLUSION The ozone AHT did not cause evident RVR in the macular area, whereas the peripapillary area showed a partial response.
Collapse
Affiliation(s)
- Eyüp Düzgün
- Department of Ophthalmology, Sisli Hamidiye Etfal Training and Research Hospital, University of Health Sciences, Istanbul, Turkey.
| | - Tülay Şahin
- Department of Physical Therapy and Rehabilitation, Sisli Hamidiye Etfal Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Sümeyra Keleş Yeşiltaş
- Department of Ophthalmology, Sisli Hamidiye Etfal Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Abdurrahman Alpaslan Alkan
- Department of Ophthalmology, Sisli Hamidiye Etfal Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Nejla Tükenmez Dikmen
- Department of Ophthalmology, Sultan Abdulhamid Han Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| |
Collapse
|
9
|
van der Heide FCT, van Sloten TT, Willekens N, Stehouwer CDA. Neurovascular coupling unit dysfunction and dementia: Retinal measurements as tools to move towards population-based evidence. Front Endocrinol (Lausanne) 2022; 13:1014287. [PMID: 36506058 PMCID: PMC9727310 DOI: 10.3389/fendo.2022.1014287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 10/31/2022] [Indexed: 11/24/2022] Open
Abstract
Dysfunction of the neurovascular coupling unit may be an important contributor to dementia. The neurovascular coupling unit comprises neuronal structures (e.g. astrocytes) and vascular structures (e.g. endothelial cells) that functionally interact both at the level of the arterioles as well as at the capillary level (blood-brain barrier) to regulate optimal metabolic conditions in the brain. However, it remains unclear how and to what extent dysfunction of the neurovascular coupling unit contributes to the early-stage pathobiology of dementia. Currently, limited data are available on the association between neurovascular coupling unit dysfunction, as quantified by cerebral imaging techniques, and cognitive performance. In particular, there is a lack of population-based human data (defined as studies with a sample size ~n>500). This is an important limitation because population-based studies, in comparison with smaller clinical studies, provide data which is better representative of the general population; are less susceptible to selection bias; and have a larger statistical power to detect small associations. To acquire population-based data, however, alternative imaging techniques than cerebral imaging techniques may be required. Disadvantages of cerebral imaging techniques, which limit use in population-based studies, are that these techniques are relatively expensive, time-consuming, and/or invasive. In this review, we propose that retinal imaging techniques can be used for population-based studies: on the one hand the retina and brain have many anatomical and physiological similarities; and on the other hand retinal imaging techniques are non-invasive, highly accurate, relatively inexpensive, and require relatively short measurement time. To provide support for this concept, we provide an overview on the human (population-based) evidence on the associations of retinal indices of neurodegeneration, microvascular dysfunction, and dysfunction of the neurovascular coupling unit with magnetic resonance imaging (MRI) features of structural brain abnormalities and cognitive performance.
Collapse
Affiliation(s)
- Frank C. T. van der Heide
- CARIM School for Cardiovascular Diseases, Maastricht University (UM), Maastricht, Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+ (MUMC+), Maastricht, Netherlands
- Department of Psychiatry and Neuropsychology, MUMC+, Maastricht, Netherlands
- School of Mental Health and Neuroscience, MUMC+, Maastricht, Netherlands
- *Correspondence: Frank C. T. van der Heide,
| | - Thomas T. van Sloten
- CARIM School for Cardiovascular Diseases, Maastricht University (UM), Maastricht, Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+ (MUMC+), Maastricht, Netherlands
| | - Nele Willekens
- CARIM School for Cardiovascular Diseases, Maastricht University (UM), Maastricht, Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+ (MUMC+), Maastricht, Netherlands
| | - Coen D. A. Stehouwer
- CARIM School for Cardiovascular Diseases, Maastricht University (UM), Maastricht, Netherlands
- Department of Internal Medicine, Maastricht University Medical Center+ (MUMC+), Maastricht, Netherlands
| |
Collapse
|
10
|
Yan C, Li F, Hou M, Ye X, Su L, Hu Y, Luo J, Chi W. Vascular Abnormalities in Peripapillary and Macular Regions of Behcet's Uveitis Patients Evaluated by Optical Coherence Tomography Angiography. Front Med (Lausanne) 2021; 8:727151. [PMID: 34604263 PMCID: PMC8481620 DOI: 10.3389/fmed.2021.727151] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/24/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: To investigate the involvement of peripapillary zone vascular abnormalities in Behcet's uveitis (BU) and associated visual dysfunction. We evaluated the retinal and choroidal microvascular features in both macular and peripapillary areas of BU patients to identify vascular abnormalities contributing to reduced best-corrected visual acuity (BCVA) using optical coherence tomography angiography (OCTA). Methods: A prospective, observational study was conducted in 24 eyes of 13 patients with BU and 24 eyes of 15 healthy participants as controls. They received a standard eye examination and were recorded by OCTA measurements of macular and peripapillary areas. The vascular densities of superficial capillary plexus (SCP) and deep capillary plexus (DCP), choroidal flow area, radial peripapillary capillary network (RPCN) density, foveal avascular zone (FAZ) area and perimeter, full retinal thickness (FRT), and peripapillary retinal nerve fiber layer thickness (pRNFLT) were measured.Correlations among microvascular, structural, and functional changes were assessed. Results: Our findings uncovered that the vascular density was significantly reduced in the peripapillary zone of BU eyes compared to healthy eyes, especially in the inferior subfield of the RPCN. The vascular densities of SCP and DCP quadrants within the macular zone had no significant difference between BU and control groups except for DCP density of the nasal parafoveal quadrant. Both FAZ area and perimeter were greater but without statistical significance in the BU group. Compared to healthy eyes, the choriocapillaris flow area was smaller while the FRT and pRNFLT were greater in the BU group. Notably, there was a significant correlation between the reduction in RPCN vascular density and decreased BCVA in BU patients. Conclusion: Based on OCTA, vascular changes associated with BU are more prominent in the peripapillary zone than those in the macular zone. The vascular density of the RPCN could serve as a sensitive indicator to monitoring BU pathogenic progression and treatment response using a non-invasively method of OCTA.
Collapse
Affiliation(s)
- Chun Yan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Fan Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Min Hou
- Department of Ophthalmology, Luoyang Central Hospital, Zhengzhou University, Luoyang, China
| | - Xiaoyuan Ye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lishi Su
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yixin Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jiawen Luo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wei Chi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| |
Collapse
|
11
|
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
|
12
|
Retinal blood flow reversal quantitatively monitored in out-of-plane vessels with laser Doppler holography. Sci Rep 2021; 11:17828. [PMID: 34497299 PMCID: PMC8426375 DOI: 10.1038/s41598-021-96877-5] [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] [Received: 12/28/2020] [Accepted: 08/05/2021] [Indexed: 12/29/2022] Open
Abstract
Laser Doppler holography is a planar blood flow imaging technique recently introduced in ophthalmology to image human retinal and choroidal blood flow non-invasively. Here we present a digital method based on the Doppler spectrum asymmetry that reveals the local direction of blood flow with respect to the optical axis in out-of-plane vessels. This directional information is overlaid on standard grayscale blood flow images to depict flow moving towards the camera in red and flow moving away from the camera in blue, as in ultrasound color Doppler imaging. We show that thanks to the strong contribution of backscattering to the Doppler spectrum in out-of-plane vessels, the local axial direction of blood flow can be revealed with a high temporal resolution, which enables us to evidence pathological blood flow reversals. We also demonstrate the use of optical Doppler spectrograms to quantitatively monitor retinal blood flow reversals.
Collapse
|
13
|
Truffer F, Geiser M, Chappelet MA, Strese H, Maître G, Amoos S, Aptel F, Chiquet C. Absolute retinal blood flowmeter using a laser Doppler velocimeter combined with adaptive optics. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200254R. [PMID: 33236618 PMCID: PMC7685387 DOI: 10.1117/1.jbo.25.11.115002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 11/04/2020] [Indexed: 06/11/2023]
Abstract
SIGNIFICANCE The development of a technique allowing for non-invasive measurement of retinal blood flow (RBF) in humans is needed to understand many retinal vascular diseases (pathophysiology) and evaluate treatment with potential improvement of blood flow. AIM We developed and validated an absolute laser Doppler velocimeter (LDV) based on an adaptive optical fundus camera that provides simultaneously high-definition images of the fundus vessels and absolute maximal red blood cells (RBCs) velocity to calculate the absolute RBF. APPROACH This new absolute LDV is combined with the adaptive optics (AO) fundus camera (rtx1, Imagine Eyes©, Orsay, France) outside its optical wavefront correction path. A 4-s recording includes 40 images, each synchronized with two Doppler shift power spectra. Image analysis provides a vessel diameter close to the probing beam, and the velocity of the RBCs in the vessels are extracted from the Doppler spectral analysis. A combination of these values gives an average of the absolute RBF. RESULTS An in vitro experiment consisting of latex microspheres flowing in water through a glass capillary to simulate a blood vessel and in vivo measurements on six healthy humans was done to assess the device. In the in vitro experiment, the calculated flow varied between 1.75 and 25.9 μL / min and was highly correlated (r2 = 0.995) with the flow imposed by a syringe pump. In the in vivo experiment, the error between the flow in the parent vessel and the sum of the flow in the daughter vessels was between -11 % and 36% (mean ± sd, 5.7 ± 18.5 % ). RBF in the main temporal retinal veins of healthy subjects varied between 0.9 and 13.2 μL / min. CONCLUSIONS The AO LDV prototype allows for the real-time measurement of absolute RBF derived from the retinal vessel diameter and the maximum RBCs velocity in that vessel.
Collapse
Affiliation(s)
- Frederic Truffer
- University of Applied Sciences and Arts of Western Switzerland, Institute of System Engineering, Sion, Switzerland
| | - Martial Geiser
- University of Applied Sciences and Arts of Western Switzerland, Institute of System Engineering, Sion, Switzerland
| | | | - Helene Strese
- University of Applied Sciences and Arts of Western Switzerland, Institute of System Engineering, Sion, Switzerland
| | - Gilbert Maître
- University of Applied Sciences and Arts of Western Switzerland, Institute of System Engineering, Sion, Switzerland
| | - Serge Amoos
- University of Applied Sciences and Arts of Western Switzerland, Institute of System Engineering, Sion, Switzerland
| | - Florent Aptel
- University Hospital, Department of Ophthalmology, Grenoble, France
- Grenoble Alpes University, Faculty of Humanities, Health, Sport and Society, Grenoble, France
- Inserm, CHU Grenoble Alpes, HP2, Grenoble, France
| | - Christophe Chiquet
- University Hospital, Department of Ophthalmology, Grenoble, France
- Grenoble Alpes University, Faculty of Humanities, Health, Sport and Society, Grenoble, France
- Inserm, CHU Grenoble Alpes, HP2, Grenoble, France
| |
Collapse
|
14
|
Bansal M, Rangarajan K. Commentary: Retinal hemodynamics, retrobulbar circulation and the use of color doppler imaging. Indian J Ophthalmol 2020; 68:2623. [PMID: 33120716 PMCID: PMC7774188 DOI: 10.4103/ijo.ijo_1378_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Mayank Bansal
- Department of Ophthalmology, Fortis Memorial Research Institute, Gurugram, Haryana, India
| | - Krithika Rangarajan
- Department of Radiology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India
| |
Collapse
|
15
|
Puchner S, Schmidl D, Ginner L, Augustin M, Leitgeb R, Szegedi S, Stjepanek K, Hommer N, Kallab M, Werkmeister RM, Schmetterer L, Garhofer G. Changes in Retinal Blood Flow in Response to an Experimental Increase in IOP in Healthy Participants as Assessed With Doppler Optical Coherence Tomography. Invest Ophthalmol Vis Sci 2020; 61:33. [PMID: 32084274 PMCID: PMC7326607 DOI: 10.1167/iovs.61.2.33] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Blood flow autoregulation is an intrinsic mechanism of the healthy retinal vasculature to keep blood flow constant when ocular perfusion pressure (OPP) is changed. In the present study, we set out to investigate retinal blood flow in response to an experimental decrease in OPP in healthy participants using Doppler optical coherence tomography. Methods Fifteen healthy participants aged between 22 and 31 years (mean, 27 ± 3 years) were included in the present open study. IOP was increased stepwise via the suction cup method to induce a decrease in OPP. Retinal blood flow in arteries and veins was assessed using a custom-built Doppler optical coherence tomography system and pressure–flow relationships were calculated to assess autoregulation. Results Suction cup application induced a pronounced increase in IOP with a maximum value of 50.5 ± 8.0 mm Hg at the highest level of suction. Pressure–flow relationships revealed that blood flow was autoregulated until the OPP was decreased by approximately 21 mm Hg and started to decrease significantly when the OPP was reduced by 30 mm Hg. Retinal blood flow at the last suction period decreased at a maximum of –57.0 ± 22.3% and 65.2 ± 15.4% in retinal arteries and retinal veins, respectively. These changes in retinal blood flow were less pronounced than the decrease in OPP (–75.2 ± 19.2%), indicating retinal autoregulation. Conclusions The results of the present study confirm that retinal blood flow is autoregulated in response to changes in the OPP. Doppler optical coherence tomography has the potential to become a clinical tool for the investigation of retinal blood flow autoregulation in the future, because of its ability to assess the blood velocities and diameter of the retinal vessels parallel and therefore also their blood flow in absolute values. (Clinicaltrials.gov number NCT03398616)
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Leopold Schmetterer
- ,.,,.,.,.,.,,.,,
| | | |
Collapse
|
16
|
Burns SA, Elsner AE, Sapoznik KA, Warner RL, Gast TJ. Adaptive optics imaging of the human retina. Prog Retin Eye Res 2019; 68:1-30. [PMID: 30165239 PMCID: PMC6347528 DOI: 10.1016/j.preteyeres.2018.08.002] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/18/2022]
Abstract
Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.
Collapse
Affiliation(s)
- Stephen A Burns
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States.
| | - Ann E Elsner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kaitlyn A Sapoznik
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Raymond L Warner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Thomas J Gast
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| |
Collapse
|
17
|
Christodoulou P, Katsimpris I. Treatment controversies in a rare case of a simultaneous branch retinal artery and vein occlusion secondary to hyperhomocysteinemia and hypertension. Int J Ophthalmol 2018; 11:2024-2026. [PMID: 30588441 PMCID: PMC6288539 DOI: 10.18240/ijo.2018.12.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 07/09/2018] [Indexed: 11/23/2022] Open
Affiliation(s)
- Panayiotis Christodoulou
- General Hospital of Patras "Agios Andreas", Ophthalmology Clinic, Kalavriton 37, Patras 26335, Greece
| | - Ioannis Katsimpris
- General Hospital of Patras "Agios Andreas", Ophthalmology Clinic, Kalavriton 37, Patras 26335, Greece
| |
Collapse
|
18
|
Orlando JI, Barbosa Breda J, van Keer K, Blaschko MB, Blanco PJ, Bulant CA. Towards a Glaucoma Risk Index Based on Simulated Hemodynamics from Fundus Images. ACTA ACUST UNITED AC 2018. [DOI: 10.1007/978-3-030-00934-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
|
19
|
Wei X, Balne PK, Meissner KE, Barathi VA, Schmetterer L, Agrawal R. Assessment of flow dynamics in retinal and choroidal microcirculation. Surv Ophthalmol 2018; 63:646-664. [DOI: 10.1016/j.survophthal.2018.03.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 03/19/2018] [Accepted: 03/19/2018] [Indexed: 01/08/2023]
|
20
|
Takagi S, Hirami Y, Takahashi M, Fujihara M, Mandai M, Miyakoshi C, Tomita G, Kurimoto Y. Optical coherence tomography angiography in patients with retinitis pigmentosa who have normal visual acuity. Acta Ophthalmol 2018; 96:e636-e642. [PMID: 29498230 PMCID: PMC6175316 DOI: 10.1111/aos.13680] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 11/21/2017] [Indexed: 01/16/2023]
Abstract
PURPOSE To investigate flow area changes measured using optical coherence tomography angiography (OCTA; RTVue XR Avanti® ) in patients with retinitis pigmentosa (RP) with preserved visual acuity (VA). METHODS This was an age- and refraction-matched case-control study. Consecutive patients with a best-corrected visual acuity (BCVA) of ≥20/20 and normal subjects were recruited. Fifty eyes (32 patients) and 22 eyes (12 controls) were included. The flow area and foveal avascular zone (FAZ) were measured in both superficial and deep layers within a 3 × 3 mm central area of the fovea. Association between OCTA parameters and the length of the inner segment ellipsoid (ISe) and external limiting membrane (ELM), the area without abnormal fluorescence in fundus autofluorescence (normal FAF area ratio) and the area of I-2e of the Goldmann perimeter were analysed using mixed-effects regression analysis. RESULTS Foveal avascular zones were significantly smaller in patients with RP than in controls in superficial (p = 0.004) but not in deep layers (p = 0.25). The flow area in superficial (p = 0.007) and deep layers (p = 0.004) was significantly smaller in patients with RP than in controls. In patients with RP, flow areas in the superficial layers, but not in the deep layers, were significantly associated with the lengths of ISe (p = 0.001) and ELM (p = 0.002) and the I-2e area (p = 0.036), but not with the normal FAF area ratio (p = 0.399). CONCLUSION Optical coherence tomography angiography (OCTA)-measured flow area in superficial layers gradually reduced with RP progression and may be a useful parameter of RP pathogenesis.
Collapse
Affiliation(s)
- Seiji Takagi
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- Department of Translational Research, Division of Ophthalmology; Institute of Biomedical Research and Innovation; Kobe Japan
- Department of Ophthalmology; Toho University Ohashi Medical Center; Tokyo Japan
| | - Yasuhiko Hirami
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- Department of Translational Research, Division of Ophthalmology; Institute of Biomedical Research and Innovation; Kobe Japan
- RIKEN Center for Developmental Biology; Kobe Japan
| | - Masayo Takahashi
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- Department of Translational Research, Division of Ophthalmology; Institute of Biomedical Research and Innovation; Kobe Japan
- RIKEN Center for Developmental Biology; Kobe Japan
| | - Masashi Fujihara
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- Department of Translational Research, Division of Ophthalmology; Institute of Biomedical Research and Innovation; Kobe Japan
| | - Michiko Mandai
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- RIKEN Center for Developmental Biology; Kobe Japan
| | - Chisato Miyakoshi
- Department of Pediatrics; Kobe City Medical Center General Hospital; Kobe Japan
| | - Goji Tomita
- Department of Ophthalmology; Toho University Ohashi Medical Center; Tokyo Japan
| | - Yasuo Kurimoto
- Department of Ophthalmology; Kobe City Medical Center General Hospital; Kobe Japan
- Department of Translational Research, Division of Ophthalmology; Institute of Biomedical Research and Innovation; Kobe Japan
- RIKEN Center for Developmental Biology; Kobe Japan
| |
Collapse
|
21
|
Gu B, Wang X, Twa MD, Tam J, Girkin CA, Zhang Y. Noninvasive in vivo characterization of erythrocyte motion in human retinal capillaries using high-speed adaptive optics near-confocal imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:3653-3677. [PMID: 30338146 PMCID: PMC6191635 DOI: 10.1364/boe.9.003653] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/02/2018] [Accepted: 07/02/2018] [Indexed: 05/18/2023]
Abstract
The flow of erythrocytes in parafoveal capillaries was imaged in the living human eye with an adaptive optics near-confocal ophthalmoscope at a frame rate of 800 Hz with a low coherence near-infrared (NIR) light source. Spatiotemporal traces of the erythrocyte movement were extracted from consecutive images. Erythrocyte velocity was measured using custom software based on the Radon transform. The impact of imaging speed on velocity measurement was estimated using images of frame rates of 200, 400, and 800 Hz. The NIR light allowed for long imaging periods without visually stimulating the retina and disturbing the natural rheological state. High speed near-confocal imaging enabled direct and accurate measurement of erythrocyte velocity, and revealed a distinctively cardiac-dependent pulsatile velocity waveform of the erythrocyte flow in retinal capillaries, disclosed the impact of the leukocytes on erythrocyte motion, and provided new metrics for precise assessment of erythrocyte movement. The approach may facilitate new investigations on the pathophysiology of retinal microcirculation with applications for ocular and systemic diseases.
Collapse
Affiliation(s)
- Boyu Gu
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaolin Wang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Michael D. Twa
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, 1716 University Boulevard, Birmingham, AL 35294, USA
| | - Johnny Tam
- National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
| | - Christopher A. Girkin
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| | - Yuhua Zhang
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, 1670 University Boulevard, Birmingham, AL 35294, USA
| |
Collapse
|
22
|
Sun G, Liu X, Gao L, Zhang P, Wang S, Zhou Y. Automatic measurement of global retinal circulation in fluorescein angiography. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-8. [PMID: 29956508 DOI: 10.1117/1.jbo.23.6.065006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/04/2018] [Indexed: 06/08/2023]
Abstract
Examination of the retinal circulation in patients with retinal diseases is a clinical routine for ophthalmologists. In the present work, an automatic method is proposed for measuring the global retinal circulation in fluorescein angiography (FA). First, the perfusion region in FA images is segmented using a multiscale line detector. Then, the time evolution of the perfusion area is modeled using damped least-squares regression. Based on the perfusion area profile, some circulation parameters are defined to describe quantitatively the global retinal circulation. The effectiveness of the proposed method is tested using our own and public datasets, with reasonable results and satisfactory accuracy compared with manual measurement. The proposed method has good computing efficiency and thus has potential to be used in clinical practice for evaluation of global retinal circulation.
Collapse
Affiliation(s)
| | | | - Ling Gao
- The Second Xiangya Hospital of Central South Univ., China
| | - Pu Zhang
- The Second Xiangya Hospital of Central South Univ., China
| | | | - Yandan Zhou
- The Second Xiangya Hospital of Central South Univ., China
| |
Collapse
|
23
|
REPRODUCIBILITY OF VESSEL DENSITY MEASUREMENT WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN EYES WITH AND WITHOUT RETINOPATHY. Retina 2018; 37:1475-1482. [PMID: 27930458 DOI: 10.1097/iae.0000000000001407] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To determine the intravisit and intervisit reproducibility of optical coherence tomography angiography measurements of macular vessel density in eyes with and without retinal diseases. METHODS Fifteen healthy volunteers and 22 patients with retinal diseases underwent repeated optical coherence tomography angiography (Angiovue Imaging System, Optovue Inc) scans after pupil dilation on 2 separate visit days. For each visit day, the eyes were scanned twice. Vessel density defined as the proportion of vessel area with flowing blood over the total measurement area was calculated using Angiovue software. Intravisit and intervisit reproducibility were summarized as coefficient of variations and intraclass correlation coefficients were calculated from variance component models. RESULTS The coefficient of variations representing the intravisit reproducibility of the superficial macular vessel density measurements for different quadrants on 3 mm × 3-mm scans varied from 2.1% to 4.9% and 3.4% to 6.8% for healthy and diseased eyes, respectively, and for the intervisit it was 2.9% to 5.1% and 4.0% to 6.8%, respectively. The coefficient of variations were lower in healthy eyes than in diseased eyes, lower for intravisit than for intervisit, lower on 3 mm × 3-mm scans than on 6 mm × 6-mm scans, and lower for paracentral subfields than for central subfield. CONCLUSION The evidence presented here demonstrates good reproducibility of optical coherence tomography angiography for measurement of superficial macula vessel density in both healthy eyes and eyes with diabetic retinopathy without diabetic macular edema.
Collapse
|
24
|
Nesper PL, Soetikno BT, Zhang HF, Fawzi AA. OCT angiography and visible-light OCT in diabetic retinopathy. Vision Res 2017; 139:191-203. [PMID: 28601429 PMCID: PMC5723235 DOI: 10.1016/j.visres.2017.05.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 12/31/2022]
Abstract
In recent years, advances in optical coherence tomography (OCT) techniques have increased our understanding of diabetic retinopathy, an important microvascular complication of diabetes. OCT angiography is a non-invasive method that visualizes the retinal vasculature by detecting motion contrast from flowing blood. Visible-light OCT shows promise as a novel technique for quantifying retinal hypoxia by measuring the retinal oxygen delivery and metabolic rates. In this article, we discuss recent insights provided by these techniques into the vascular pathophysiology of diabetic retinopathy. The next milestones for these modalities are large multicenter studies to establish consensus on the most reliable and consistent outcome parameters to study diabetic retinopathy.
Collapse
Affiliation(s)
- Peter L Nesper
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA.
| | - Brian T Soetikno
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA; Medical Scientist Training Program, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA.
| | - Hao F Zhang
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
| | - Amani A Fawzi
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA.
| |
Collapse
|
25
|
Reactivity in the human retinal microvasculature measured during acute gas breathing provocations. Sci Rep 2017; 7:2113. [PMID: 28522835 PMCID: PMC5437020 DOI: 10.1038/s41598-017-02344-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/10/2017] [Indexed: 11/11/2022] Open
Abstract
Although changes in vessel diameter following gas perturbation have been documented in retinal arterioles and venules, these responses have yet to be quantified in the smallest vessels of the human retina. Here, using in vivo adaptive optics, we imaged 3–25 µm diameter vessels of the human inner retinal circulation and monitored the effects of altered gas-breathing conditions. During isocapnic hyperoxia, definite constrictions were seen in 51% of vessel segments (mean ± SD for pre-capillary arterioles −9.5 ± 3.0%; capillaries −11.8 ± 3.3%; post-capillary venules −6.3 ± 2.8%); these are comparable with responses previously reported in larger vessels. During isoxic hypercapnia, definite dilations were seen in 47% of vessel segments (mean ± SD for pre-capillary arterioles +9.8 ± 1.5%; capillaries +13.7 ± 3.8%; post-capillary venules +7.5 ± 4.2%); these are proportionally greater than responses previously reported in larger vessels. The magnitude of these proportional changes implies that the capillary beds themselves play an important role in the retinal response to changes in carbon dioxide levels. Interestingly, the distribution of microvascular responses shown here differs from our previously reported responses to flicker stimulation, suggesting differences in the way blood supply is coordinated following gas perturbation and altered neural activity.
Collapse
|
26
|
Maram J, Srinivas S, Sadda SR. Evaluating ocular blood flow. Indian J Ophthalmol 2017; 65:337-346. [PMID: 28573987 PMCID: PMC5565900 DOI: 10.4103/ijo.ijo_330_17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 05/04/2017] [Indexed: 02/01/2023] Open
Abstract
Studies have shown that vascular impairment plays an important role in the etiology and pathogenesis of various ocular diseases including glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal venous occlusive disease. Thus, qualitative and quantitative assessment of ocular blood flow (BF) is a topic of interest for early disease detection, diagnosis, and management. Owing to the rapid improvement in technology, there are several invasive and noninvasive techniques available for evaluating ocular BF, with each of these techniques having their own limitations and advantages. This article reviews these important techniques, with a particular focus on Doppler Fourier domain optical coherence tomography (OCT) and OCT-angiography.
Collapse
Affiliation(s)
- Jyotsna Maram
- Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, California, USA
| | - Sowmya Srinivas
- Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, California, USA
| | - Srinivas R Sadda
- Doheny Image Reading Center, Doheny Eye Institute, Los Angeles, California, USA
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| |
Collapse
|
27
|
Moult EM, Choi W, Boas DA, Baumann B, Clermont AC, Feener EP, Fujimoto JG. Evaluating anesthetic protocols for functional blood flow imaging in the rat eye. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:16005. [PMID: 28056146 PMCID: PMC5217081 DOI: 10.1117/1.jbo.22.1.016005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/15/2016] [Indexed: 05/27/2023]
Abstract
The purpose of this study is to evaluate the suitability of five different anesthetic protocols (isoflurane, isoflurane–xylazine, pentobarbital, ketamine–xylazine, and ketamine–xylazine–vecuronium) for functional blood flow imaging in the rat eye. Total retinal blood flow was measured at a series of time points using an ultrahigh-speed Doppler OCT system. Additionally, each anesthetic protocol was qualitatively evaluated according to the following criteria: (1) time-stability of blood flow, (2) overall rate of blood flow, (3) ocular immobilization, and (4) simplicity. We observed that different anesthetic protocols produced markedly different blood flows. Different anesthetic protocols also varied with respect to the four evaluated criteria. These findings suggest that the choice of anesthetic protocol should be carefully considered when designing and interpreting functional blood flow studies in the rat eye.
Collapse
Affiliation(s)
- Eric M. Moult
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
| | - WooJhon Choi
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
| | - David A. Boas
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 13th Street, Charlestown 02129, United States
| | - Bernhard Baumann
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Guertel 18, Vienna 1090, Austria
| | - Allen C. Clermont
- Joslin Diabetes Center, Research Division, One Joslin Place, Boston 02215, United States
| | - Edward P. Feener
- Joslin Diabetes Center, Research Division, One Joslin Place, Boston 02215, United States
| | - James G. Fujimoto
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
| |
Collapse
|
28
|
Evidence of Flicker-Induced Functional Hyperaemia in the Smallest Vessels of the Human Retinal Blood Supply. PLoS One 2016; 11:e0162621. [PMID: 27617960 PMCID: PMC5019460 DOI: 10.1371/journal.pone.0162621] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/25/2016] [Indexed: 12/02/2022] Open
Abstract
Regional changes in blood flow are initiated within neural tissue to help fuel local differences in neural activity. Classically, this response was thought to arise only in larger arterioles and venules. However, recently, it has been proposed that a) the smallest vessels of the circulation make a comparable contribution, and b) the response should be localised intermittently along such vessels, due to the known distribution of contractile mural cells. To assess these hypotheses in human neural tissue in vivo, we imaged the retinal microvasculature (diameters 3–28 μm) non-invasively, using adaptive optics, before and after delivery of focal (360 μm) patches of flickering visible light. Our results demonstrated a definite average response in 35% of all vessel segments analysed. In these responding vessels, the magnitude of proportional dilation (mean ± SEM for pre-capillary arterioles 13 ± 5%, capillaries 31 ± 8%, and post-capillary venules 10 ± 3%) is generally far greater than the magnitudes we and others have measured in the larger retinal vessels, supporting proposition a) above. The dilations observed in venules were unexpected based on previous animal work, and may be attributed either to differences in stimulus or species. Response heterogeneity across the network was high; responses were also heterogeneous along individual vessels (45% of vessel segments showed demonstrable locality in their response). These observations support proposition b) above. We also observed a definite average constriction across 7% of vessel segments (mean ± SEM constriction for capillaries -16 ± 3.2%, and post-capillary venules -18 ± 12%), which paints a picture of dynamic redistribution of flow throughout the smallest vessel networks in the retina in response to local, stimulus-driven metabolic demand.
Collapse
|
29
|
Rajagopal R, Apte RS. Seeing through thick and through thin: Retinal manifestations of thrombophilic and hyperviscosity syndromes. Surv Ophthalmol 2015; 61:236-47. [PMID: 26519860 DOI: 10.1016/j.survophthal.2015.10.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/21/2015] [Accepted: 10/23/2015] [Indexed: 01/23/2023]
Abstract
The presence of retinal vasculopathy in the absence of typical predisposing factors should suggest a possible underlying hematologic abnormality. In such cases, a systemic investigation may reveal a potentially fatal hypercoagulability or hyperviscosity syndrome. Retinal vein occlusion is the most commonly encountered ophthalmic finding in such syndromes; however, abnormalities of the arterial system, the choroid, and the macula are also possible. Visual symptoms may be the only manifestation of the underlying process, making timely diagnosis by the ophthalmologist critical for both treatment and thrombotic prophylaxis. Moreover, as newer ophthalmic diagnostic technologies arise, there is an increasingly important role for eye physicians in the management of such syndromes.
Collapse
Affiliation(s)
- Rithwick Rajagopal
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri, USA.
| | - Rajendra S Apte
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri, USA.
| |
Collapse
|
30
|
Cheung CY, Ikram MK, Klein R, Wong TY. The clinical implications of recent studies on the structure and function of the retinal microvasculature in diabetes. Diabetologia 2015; 58:871-85. [PMID: 25669631 DOI: 10.1007/s00125-015-3511-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/12/2015] [Indexed: 12/26/2022]
Abstract
The retinal blood vessels provide the opportunity to study early structural and functional changes in the microvasculature prior to clinically significant microvascular and macrovascular complications of diabetes. Advances in digital retinal photography and computerised assessment of the retinal vasculature have provided more objective and precise measurements of retinal vascular changes. Clinic- and population-based studies have reported that these quantitatively measured retinal vascular changes (e.g. retinal arteriolar narrowing and venular widening) are associated with preclinical structural changes in other microvascular systems (e.g. infarct in the cerebral microcirculation), as well as diabetes and diabetic complications, suggesting that they are markers of early microvascular dysfunction. In addition, there are new retinal imaging techniques to further assess alterations in retinal vascular function (e.g. flicker-induced vasodilatory response, blood flow and oxygen saturation) in diabetes and complications that result from the effects of chronic hyperglycaemia, inflammation and endothelial dysfunction. In this review, we summarise the latest findings on the relationships between quantitatively measured structural and functional retinal vascular changes with diabetes and diabetic complications. We also discuss clinical implications and future research to evaluate whether detection of retinal vascular changes has additional value beyond that achieved with methods currently used to stratify the risk of diabetes and its complications.
Collapse
Affiliation(s)
- Carol Yimlui Cheung
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, 11 Third Hospital Avenue, Singapore, 168751, Republic of Singapore
| | | | | | | |
Collapse
|
31
|
Abstract
Blood flow is a useful indicator of the metabolic state of the retina. However, accurate measurement of retinal blood flow is difficult to achieve in practice. Most existing optical techniques used for measuring blood flow require complex assumptions and calculations. We describe here a simple and direct method for calculating absolute blood flow in vessels of all sizes in the rat retina. The method relies on ultrafast confocal line scans to track the passage of fluorescently labeled red blood cells (fRBCs). The accuracy of the blood flow measurements was verified by (1) comparing blood flow calculated independently using either flux or velocity combined with diameter measurements, (2) measuring total retinal blood flow in arterioles and venules, (3) measuring blood flow at vessel branch points, and (4) measuring changes in blood flow in response to hyperoxic and hypercapnic challenge. Confocal line scans oriented parallel and diagonal to vessels were used to compute fRBC velocity and to examine velocity profiles across the width of vessels. We demonstrate that these methods provide accurate measures of absolute blood flow and velocity in retinal vessels of all sizes.
Collapse
|
32
|
Kim NY, Seo HR, Rho SH. The Relationships among Delayed Recovery in Finger Temperature, Nocturnal Dip, and Glaucoma Progression. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2015. [DOI: 10.3341/jkos.2015.56.1.70] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Nam Yeong Kim
- Department of Ophthalmology, Dong-A University College of Medicine, Busan, Korea
| | - Hong Ryung Seo
- Department of Ophthalmology, Wallace Memorial Baptist Hospital, Busan, Korea
| | - Sae Heun Rho
- Department of Ophthalmology, Dong-A University College of Medicine, Busan, Korea
| |
Collapse
|
33
|
Told R, Palkovits S, Boltz A, Schmidl D, Napora KJ, Werkmeister RM, Haslacher H, Frantal S, Popa‐Cherecheanu A, Schmetterer L, Garhöfer G. Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects. Acta Ophthalmol 2014; 92:e540-5. [PMID: 24863099 PMCID: PMC4225479 DOI: 10.1111/aos.12433] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 03/17/2014] [Indexed: 02/02/2023]
Abstract
Purpose The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele. Methods One hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed. Results Eighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups. Conclusions Our data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects.
Collapse
Affiliation(s)
- Reinhard Told
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Stefan Palkovits
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - Agnes Boltz
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - Katarzyna J. Napora
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Helmuth Haslacher
- Department of Laboratory Medicine Medical University of Vienna Vienna Austria
| | - Sophie Frantal
- Center for Medical Statistics Informatics and Intelligence Systems Medical University of Vienna Vienna Austria
| | | | - Leopold Schmetterer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| |
Collapse
|
34
|
Anayol MA, Toklu Y, Kamberoglu EA, Raza S, Arifoglu HB, Simavli H, Altintas AGK, Simsek S. Short-term effects of intravitreal triamcinolone acetonide injection on ocular blood flow evaluated with color Doppler ultrasonography. Int J Ophthalmol 2014; 7:811-5. [PMID: 25349798 DOI: 10.3980/j.issn.2222-3959.2014.05.13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 12/26/2013] [Indexed: 12/23/2022] Open
Abstract
AIM To evaluate the changes in ocular blood flow with color Doppler ultrasonography (CDU) after intravitreal triamcinolone acetonide (IVTA) injection. METHODS A total of 46 patients who underwent IVTA (4 mg/0.1 mL) injection for diabetic macular edema (DME) (n=22), central retinal vein occlusion (CRVO) (n=12) and choroidal neovascular membrane (CNVM) (n=12) were included in the study. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI) were measured from the ophthalmic artery (OA), the central retinal artery (CRA) and the posterior ciliary artery (PCA) of each patient with CDU before, at the end of the first week and at the end of the first month following IVTA injection. RESULTS In the DME group, PSV of OA at the first of the first month (mean±SD) (37.48±10.87 cm/s) increased compared to pre-injection value (31.39±10.84 cm/s) (P=0.048). There was a statistically significant decrease (P=0.049) in PSV of CRA at the end of the first month (7.97±2.67 cm/s) compared to the pre-injection (9.47±3.37 cm/s). There was not any statistically significant difference on the other parameters in the DME group. Also, there was not any statistically significant difference on the ocular blood flow values in the CRVO and CNVM groups. CONCLUSION We observed that 4 mg/0.1 mL IVTA increased PSV of OA and decreased PSV of CRA in DME patients and did not have any effect on ocular blood flow values of CRVO and CNVM patients.
Collapse
Affiliation(s)
| | - Yasin Toklu
- Department of Ophthalmology, Ataturk Training and Research Hospital, Ankara 06800, Turkey
| | - Elif Asik Kamberoglu
- Department of Radiology, Kecioren Training and Research Hospital, Ankara 06280, Turkey
| | - Sabri Raza
- Department of Ophthalmology, Ataturk Training and Research Hospital, Ankara 06800, Turkey
| | - Hasan Basri Arifoglu
- Department of Ophthalmology, Kayseri Training and Research Hospital, Kayseri 38010, Turkey
| | - Huseyin Simavli
- Department of Ophthalmology, Bolu Izzet Baysal State Hospital, Bolu 14030, Turkey
| | | | - Saban Simsek
- Department of Ophthalmology, Yildirim Beyazit University School of Medicine, Ankara 06800, Turkey
| |
Collapse
|
35
|
Palkovits S, Told R, Schmidl D, Boltz A, Napora KJ, Lasta M, Kaya S, Werkmeister RM, Popa-Cherecheanu A, Garhöfer G, Schmetterer L. Regulation of retinal oxygen metabolism in humans during graded hypoxia. Am J Physiol Heart Circ Physiol 2014; 307:H1412-8. [PMID: 25217648 DOI: 10.1152/ajpheart.00479.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Animal experiments indicate that the inner retina keeps its oxygen extraction constant despite systemic hypoxia. For the human retina no such data exist. In the present study we hypothesized that systemic hypoxia does not alter inner retinal oxygen extraction. To test this hypothesis we included 30 healthy male and female subjects aged between 18 and 35 years. All subjects were studied at baseline and during breathing 12% O₂ in 88% N₂ as well as breathing 15% O₂ in 85% N₂. Oxygen saturation in a retinal artery (SO₂art) and an adjacent retinal vein (SO₂vein) were measured using spectroscopic fundus reflectometry. Measurements of retinal venous blood velocity using bidirectional laser Doppler velocimetry and retinal venous diameters using a Retinal Vessel Analyzer (RVA) were combined to calculate retinal blood flow. Oxygen and carbon dioxide partial pressure were measured from earlobe arterialized capillary blood. Retinal blood flow was increased by 43.0 ± 23.2% (P < 0.001) and 30.0 ± 20.9% (P < 0.001) during 12% and 15% O₂ breathing, respectively. SO₂art as well as SO₂vein decreased during both 12% O₂ breathing (SO₂art: -11.2 ± 4.3%, P < 0.001; SO₂vein: -3.9 ± 8.5%, P = 0.012) and 15% O₂ breathing (SO₂art: -7.9 ± 3.6%, P < 0.001; SO₂vein: -4.0 ± 7.0%, P = 0.010). The arteriovenous oxygen difference decreased during both breathing periods (12% O2: -28.9 ± 18.7%; 15% O₂: -19.1 ± 16.7%, P < 0.001 each). Calculated oxygen extraction did, however, not change during our experiments (12% O₂: -2.8 ± 18.9%, P = 0.65; 15% O₂: 2.4 ± 15.8%, P = 0.26). Our results indicate that in healthy humans, oxygen extraction of the inner retina remains constant during systemic hypoxia.
Collapse
Affiliation(s)
- Stefan Palkovits
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Reinhard Told
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Agnes Boltz
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | - Katarzyna J Napora
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Lasta
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Semira Kaya
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| | | | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; and
| |
Collapse
|
36
|
Vellonen KS, Malinen M, Mannermaa E, Subrizi A, Toropainen E, Lou YR, Kidron H, Yliperttula M, Urtti A. A critical assessment of in vitro tissue models for ADME and drug delivery. J Control Release 2014; 190:94-114. [DOI: 10.1016/j.jconrel.2014.06.044] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/22/2014] [Accepted: 06/23/2014] [Indexed: 12/22/2022]
|
37
|
Willerslev A, Li XQ, Munch IC, Larsen M. Flow patterns on spectral-domain optical coherence tomography reveal flow directions at retinal vessel bifurcations. Acta Ophthalmol 2014; 92:461-4. [PMID: 23819809 DOI: 10.1111/aos.12233] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To study intravascular characteristics of flowing blood in retinal vessels using spectral-domain optical coherence tomography (SD-OCT). METHODS Examination of selected arterial bifurcations and venous sites of confluence in 25 healthy 11-year-old children recruited as an ad hoc subsample from the population-based, observational Copenhagen Child Cohort 2000 study. RESULTS The blood stream in retinal arteries maintains a figure-of-8 SD-OCT profile consistent with a laminar flow in concentric sheets and a parabolic velocity distribution up to the point of divergence at arterial bifurcations. In contrast, the blood stream at the site of confluence of two retinal veins remains divided into two parallel sets of sheets with separate velocity distribution for a downstream distance of at least four trunk vessel diameters. Consequently, retinal trunk vessels near bifurcations/confluences have distinctly different internal SD-OCT profiles, a figure-of-8 pattern in arteries and a figure figure-of-88 in veins that can be used to distinguish between the two vessel types. CONCLUSION This study verified the hypothesis that directions of blood flow at dichotomous vascular branchings can be determined using SD-OCT. This feature may assist the identification of flow reversal near sites of vascular occlusion, the analysis of blood flow near vascular malformations and the segmentation of retinal SD-OCT images.
Collapse
Affiliation(s)
- Anne Willerslev
- Department of Ophthalmology, Glostrup Hospital, Glostrup, DenmarkFaculty of Health Sciences, University of Copenhagen, Copenhagen, DenmarkDepartment of Ophthalmology, Roskilde Hospital, Roskilde, Denmark
| | | | | | | |
Collapse
|
38
|
Malek J, Azar AT, Tourki R. Impact of retinal vascular tortuosity on retinal circulation. Neural Comput Appl 2014. [DOI: 10.1007/s00521-014-1657-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
39
|
Abstract
Gender medicine has been a major focus of research in recent years. The present review focuses on gender differences in the epidemiology of the most frequent ocular diseases that have been found to be associated with impaired ocular blood flow, such as age-related macular degeneration, glaucoma and diabetic retinopathy. Data have accumulated indicating that hormones have an important role in these diseases, since there are major differences in the prevalence and incidence between men and pre- and post-menopausal women. Whether this is related to vascular factors is, however, not entirely clear. Interestingly, the current knowledge about differences in ocular vascular parameters between men and women is sparse. Although little data is available, estrogen, progesterone and testosterone are most likely important regulators of blood flow in the retina and choroid, because they are key regulators of vascular tone in other organs. Estrogen seems to play a protective role since it decreases vascular resistance in large ocular vessels. Some studies indicate that hormone therapy is beneficial for ocular vascular disease in post-menopausal women. This evidence is, however, not sufficient to give any recommendation. Generally, remarkably few data are available on the role of sex hormones on ocular blood flow regulation, a topic that requires more attention in the future.
Collapse
Affiliation(s)
- Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna , Vienna , Austria
| | | | | | | |
Collapse
|
40
|
Leitgeb RA, Werkmeister RM, Blatter C, Schmetterer L. Doppler optical coherence tomography. Prog Retin Eye Res 2014; 41:26-43. [PMID: 24704352 PMCID: PMC4073226 DOI: 10.1016/j.preteyeres.2014.03.004] [Citation(s) in RCA: 227] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/21/2014] [Accepted: 03/26/2014] [Indexed: 11/19/2022]
Abstract
Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases.
Collapse
Affiliation(s)
- Rainer A Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Cedric Blatter
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; Department of Clinical Pharmacology, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
| |
Collapse
|
41
|
Wanek J, Teng PY, Blair NP, Shahidi M. Inner retinal oxygen delivery and metabolism in streptozotocin diabetic rats. Invest Ophthalmol Vis Sci 2014; 55:1588-93. [PMID: 24550355 DOI: 10.1167/iovs.13-13537] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The purpose of the study is to report global measurements of inner retinal oxygen delivery (DO2_IR) and oxygen metabolism (MO2_IR) in streptozotocin (STZ) diabetic rats. METHODS Phosphorescence lifetime and blood flow imaging were performed in rats 4 (STZ/4 wk; n = 10) and 6 (STZ/6 wk; n = 10) weeks following injection of STZ to measure retinal arterial (O2A) and venous (O2V) oxygen contents and total retinal blood flow (F). DO2_IR and MO2_IR were calculated from measurements of F and O2A and of F and the arteriovenous oxygen content difference, respectively. Data in STZ rats were compared to those in healthy control rats (n = 10). RESULTS Measurements of O2A and O2V were not significantly different among STZ/4 wk, STZ/6 wk, and control rats (P ≥ 0.28). Likewise, F was similar among all groups of rats (P = 0.81). DO2_IR measurements were 941 ± 231, 956 ± 232, and 973 ± 243 nL O2/min in control, STZ/4 wk, and STZ/6 wk rats, respectively (P = 0.95). MO2_IR measurements were 516 ± 175, 444 ± 103, and 496 ± 84 nL O2/min in control, STZ/4 wk, and STZ/6 wk rats, respectively (P = 0.37). CONCLUSIONS Global inner retinal oxygen delivery and metabolism were not significantly impaired in STZ rats in early diabetes.
Collapse
Affiliation(s)
- Justin Wanek
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois
| | | | | | | |
Collapse
|
42
|
Werkmeister RM, Vietauer M, Knopf C, Fürnsinn C, Leitgeb RA, Reitsamer H, Gröschl M, Garhöfer G, Vilser W, Schmetterer L. Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:106008. [PMID: 25321400 DOI: 10.1117/1.jbo.19.10.106008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/22/2014] [Indexed: 05/22/2023]
Abstract
A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique. The system was operated with an 841-nm superluminescent diode and a charge-coupled device camera that could be operated at a line rate of 20 kHz. We show that the system is capable of quantifying the response of 100% oxygen breathing on the retinal blood flow. In six rats, we observed a decrease in retinal vessel diameters of 13.2% and a decrease in retinal blood velocity of 42.6%, leading to a decrease in retinal blood flow of 56.7%. Furthermore, in four rats, the response of retinal blood flow during stimulation with diffuse flicker light was assessed. Retinal vessel diameter and blood velocity increased by 3.4% and 28.1%, respectively, leading to a relative increase in blood flow of 36.2%. The presented technique shows much promise to quantify early changes in retinal blood flow during provocation with various stimuli in rodent models of ocular diseases in rats.
Collapse
Affiliation(s)
- René M Werkmeister
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Martin Vietauer
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Währinger Gürtel 18-20, 1090 Vienna, AustriabVienna University of Technology, Institute of Applied Physics, Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - Corinna Knopf
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Clemens Fürnsinn
- Medical University of Vienna, Department of Internal Medicine II, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Rainer A Leitgeb
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Herbert Reitsamer
- Paracelsus University, Department of Ophthalmology, Müllner Hauptstraße 48, 5020 Salzburg, Austria
| | - Martin Gröschl
- Vienna University of Technology, Institute of Applied Physics, Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria
| | - Gerhard Garhöfer
- Medical University of Vienna, Department of Clinical Pharmacology, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | | | - Leopold Schmetterer
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Währinger Gürtel 18-20, 1090 Vienna, AustriaeMedical University of Vienna, Department of Clinical Pharmacology, Währinger Gürtel 18-20, 1090 Vienna, Austria
| |
Collapse
|
43
|
|
44
|
Arciero J, Harris A, Siesky B, Amireskandari A, Gershuny V, Pickrell A, Guidoboni G. Theoretical analysis of vascular regulatory mechanisms contributing to retinal blood flow autoregulation. Invest Ophthalmol Vis Sci 2013; 54:5584-93. [PMID: 23847315 DOI: 10.1167/iovs.12-11543] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To study whether impaired retinal autoregulation is a risk factor for glaucoma, the relationship between vascular regulatory mechanisms and glaucoma progression needs to be investigated. In this study, a vascular wall mechanics model is used to predict the relative importance of regulatory mechanisms in achieving retinal autoregulation. METHODS Resistance vessels are assumed to respond to changes in pressure, shear stress, carbon dioxide (CO2), and the downstream metabolic state communicated via conducted responses. Model parameters governing wall tension are fit to pressure and diameter data from porcine retinal arterioles. The autoregulation pressure range for control and elevated levels of IOP is predicted. RESULTS The factor by which flow changes as the blood pressure exiting the central retinal artery is varied between 28 and 40 mm Hg is used to indicate the degree of autoregulation (1 indicates perfect autoregulation). In the presence of only the myogenic response mechanism, the factor is 2.06. In the presence of the myogenic and CO2 responses, the factor is 1.22. The combination of myogenic, shear, CO2, and metabolic responses yields the best autoregulation (factor of 1.10). CONCLUSIONS Model results are compared with flow and pressure data from multiple patient studies, and the combined effects of the metabolic and CO2 responses are predicted to be critical for achieving retinal autoregulation. When IOP is elevated, the model predicts a decrease in the autoregulation range toward low perfusion pressure, which is consistent with observations that glaucoma is associated with decreased perfusion pressure.
Collapse
Affiliation(s)
- Julia Arciero
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | | | | | | | | | | | | |
Collapse
|