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Kurokawa K, Nemeth M. Multifunctional adaptive optics optical coherence tomography allows cellular scale reflectometry, polarimetry, and angiography in the living human eye. BIOMEDICAL OPTICS EXPRESS 2024; 15:1331-1354. [PMID: 38404344 PMCID: PMC10890865 DOI: 10.1364/boe.505395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 02/27/2024]
Abstract
Clinicians are unable to detect glaucoma until substantial loss or dysfunction of retinal ganglion cells occurs. To this end, novel measures are needed. We have developed an optical imaging solution based on adaptive optics optical coherence tomography (AO-OCT) to discern key clinical features of glaucoma and other neurodegenerative diseases at the cellular scale in the living eye. Here, we test the feasibility of measuring AO-OCT-based reflectance, retardance, optic axis orientation, and angiogram at specifically targeted locations in the living human retina and optic nerve head. Multifunctional imaging, combined with focus stacking and global image registration algorithms, allows us to visualize cellular details of retinal nerve fiber bundles, ganglion cell layer somas, glial septa, superior vascular complex capillaries, and connective tissues. These are key histologic features of neurodegenerative diseases, including glaucoma, that are now measurable in vivo with excellent repeatability and reproducibility. Incorporating this noninvasive cellular-scale imaging with objective measurements will significantly enhance existing clinical assessments, which is pivotal in facilitating the early detection of eye disease and understanding the mechanisms of neurodegeneration.
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Affiliation(s)
- Kazuhiro Kurokawa
- Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Research Institute, Legacy Health, Portland, OR 97232, USA
| | - Morgan Nemeth
- Discoveries in Sight Research Laboratories, Devers Eye Institute, Legacy Research Institute, Legacy Health, Portland, OR 97232, USA
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [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: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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Gardiner SK, Cull G, Fortune B. Retinal Vessel Pulsatile Characteristics Associated With Vascular Stiffness Can Predict the Rate of Functional Progression in Glaucoma Suspects. Invest Ophthalmol Vis Sci 2023; 64:30. [PMID: 37335567 PMCID: PMC10284309 DOI: 10.1167/iovs.64.7.30] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 05/26/2023] [Indexed: 06/21/2023] Open
Abstract
Purpose Tissue stiffening and alterations in retinal blood flow have both been suggested as causative mechanisms of glaucomatous damage. We tested the hypothesis that retinal blood vessels also stiffen, using laser speckle flowgraphy (LSFG) to characterize vascular resistance. Methods In the longitudinal Portland Progression Project, 231 eyes of 124 subjects received LSFG scans of the optic nerve head (ONH) and automated perimetry every 6 months for six visits. Eyes were classified as either "glaucoma suspect" or "glaucoma" eyes based on the presence of functional loss on the first visit. Vascular resistance was quantified using the mean values of several instrument-defined parameterizations of the pulsatile waveform measured by LSFG, either in major vessels within the ONH (serving the retina) or in capillaries within ONH tissue, and age-adjusted using a separate group of 127 healthy eyes of 63 individuals. Parameters were compared against the severity and rate of change of functional loss using mean deviation (MD) over the six visits, within the two groups. Results Among 118 "glaucoma suspect" eyes (average MD, -0.4 dB; rate, -0.45 dB/y), higher vascular resistance was related to faster functional loss, but not current severity of loss. Parameters measured in major vessels were stronger predictors of rate than parameters measured in tissue. Among 113 "glaucoma" eyes (average MD, -4.3 dB; rate, -0.53 dB/y), higher vascular resistance was related to more severe current loss but not rate of loss. Conclusions Higher retinal vascular resistance and, by likely implication, stiffer retinal vessels were associated with more rapid functional loss in eyes without significant existing loss at baseline.
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Affiliation(s)
| | - Grant Cull
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
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Gardiner SK, Swanson WH, Mansberger SL. Long- and Short-Term Variability of Perimetry in Glaucoma. Transl Vis Sci Technol 2022; 11:3. [PMID: 35917137 PMCID: PMC9358297 DOI: 10.1167/tvst.11.8.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Purpose Test–retest variability in perimetry consists of short-term and long-term components, both of which impede assessment of progression. By minimizing and quantifying the algorithm-dependent short-term variability, we can quantify the algorithm-independent long-term variability that reflects true fluctuations in sensitivity between visits. We do this at locations with sensitivity both < 28 dB (when the stimulus is smaller than Ricco's area and complete spatial summation can be assumed) and > 28 dB (when partial summation occurs). Methods Frequency-of-seeing curves were measured at four locations of 35 participants with glaucoma. The standard deviation of cumulative Gaussian fits to those curves was modeled for a given sensitivity and used to simulate the expected short-term variability of a 30-presentation algorithm. A separate group of 137 participants was tested twice with that algorithm, 6 months apart. Long-term variance at different sensitivities was calculated as the LOESS fit of observed test–retest variance minus the LOESS fit of simulated short-term variance. Results Below 28 dB, short-term variability increased approximately linearly with increasing loss. Long-term variability also increased with damage below this point, attaining a maximum standard deviation of 2.4 dB at sensitivity 21 dB, before decreasing due to the floor effect of the algorithm. Above 30 dB, the observed test–retest variance was slightly smaller than the simulated short-term variance. Conclusions Long-term and short-term variability both increase with damage for perimetric stimuli smaller than Ricco's area. Above 28 dB, long-term variability constitutes a negligible proportion of test–retest variability. Translational Relevance Fluctuations in true sensitivity increase in glaucoma, even after accounting for increased short-term variability. This long-term variability cannot be reduced by altering testing algorithms alone.
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Musial G, Adhikari S, Mirhajianmoghadam H, Queener HM, Schill AW, Patel NB, Porter J. Longitudinal In Vivo Changes in Radial Peripapillary Capillaries and Optic Nerve Head Structure in Non-Human Primates With Early Experimental Glaucoma. Invest Ophthalmol Vis Sci 2022; 63:10. [PMID: 34994770 PMCID: PMC8742514 DOI: 10.1167/iovs.63.1.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Purpose There is conflicting evidence regarding whether a loss of radial peripapillary capillaries (RPCs) precedes neuronal loss in glaucoma. We examined the time course of in vivo changes in RPCs, optic nerve head (ONH) structure, and retinal nerve fiber layer thickness (RNFLT) in experimental glaucoma (EG). Methods Spectral domain optical coherence tomography images were acquired before and approximately every two weeks after inducing unilateral EG in nine rhesus monkeys to quantify mean anterior lamina cribrosa surface depth (ALCSD), minimum rim width (MRW), and RNFLT. Perfused RPC density was measured from adaptive optics scanning laser ophthalmoscope images acquired on the temporal half of the ONH. The time of first significant change was quantified as when values fell and remained outside of the 95% confidence interval established from control eyes. Results Mean ALCSD and/or MRW were the first parameters to change in eight EG eyes. RPC density changed first in the ninth. At their first points of change, mean ALCSD posteriorly deformed by 100.2 ± 101.2 µm, MRW thinned by 82.3 ± 65.9 µm, RNFLT decreased by 25 ± 14 µm, and RPC density decreased by 4.5 ± 2.1%. RPC density decreased before RNFL thinning in 5 EG eyes. RNFLT decreased before RPC density decreased in two EG eyes, whereas two EG eyes had simultaneous changes. Conclusions In most EG eyes, RPC density decreased before (or simultaneous with) a change in RNFLT, suggesting that vascular factors may play a role in axonal loss in some eyes in early glaucoma.
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Affiliation(s)
- Gwen Musial
- University of Houston, Houston, Texas, United States
| | | | | | | | | | | | - Jason Porter
- University of Houston, Houston, Texas, United States
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Jassim AH, Fan Y, Pappenhagen N, Nsiah NY, Inman DM. Oxidative Stress and Hypoxia Modify Mitochondrial Homeostasis During Glaucoma. Antioxid Redox Signal 2021; 35:1341-1357. [PMID: 33736457 PMCID: PMC8817702 DOI: 10.1089/ars.2020.8180] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Aims: Cellular response to hypoxia can include transition from respiration to glycolysis via upregulation of glycolytic enzymes and transporters, as well as mitophagy induction to eliminate surplus mitochondria. Our purpose was to evaluate the impact of hypoxia-inducible factor-1α (HIF-1α) stabilization on mitochondrial homeostasis and oxidative stress in a chronic model of glaucoma. Results: Retina and optic nerve (ON) were evaluated from young and aged DBA/2J (D2) glaucoma model mice and the control strain, the DBA/2-Gpnmb+. Hypoxic retinal ganglion cells (RGCs) were observed in young and aged D2 retina, with a significant increase in HIF-1α protein in the aged D2 retina. Reactive oxygen species observed in young D2 retina and ON were followed by significant decreases in antioxidant capacity in aged D2 retina and ON. HIF-1α targets such as neuron-specific glucose transporter-3 and lactate dehydrogenase were decreased or unchanged, respectively, in aged D2 retina despite an increased hypoxia response in RGCs. Mitochondrial mass was decreased in aged D2 retina concomitant with decreased mitochondrially encoded electron transport chain transcripts despite a stable nuclear-encoded TFAM (mitochondrial transcription factor), suggesting a breakdown in the nuclear-mitochondrial communication. Decreased mitophagy-associated proteins p62 and Rheb were observed in aged D2 retina, although p62 was significantly increased in the aged D2 ON. Innovation and Conclusion: The increased reactive oxygen species concomitant with HIF-1α upregulation despite reduced glucose transporters, mis-match of nuclear- and mitochondrial-encoded transcripts, and signs of reduced mitophagy suggest that retinas from D2 mice with chronic intraocular pressure elevation transition to pseudohypoxia without consistent metabolic reprogramming before significant RGC loss. Antioxid. Redox Signal. 35, 1341-1357.
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Affiliation(s)
- Assraa Hassan Jassim
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Yan Fan
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Nathaniel Pappenhagen
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
- Kent State University School of Biomedical Sciences, Kent, Ohio, USA
| | - Nana Yaa Nsiah
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Denise M. Inman
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
- Address correspondence to: Dr. Denise M. Inman, Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
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Zhao J, Gonsalvez G, Bartoli M, Mysona BA, Smith SB, Bollinger KE. Sigma 1 Receptor Modulates Optic Nerve Head Astrocyte Reactivity. Invest Ophthalmol Vis Sci 2021; 62:5. [PMID: 34086045 PMCID: PMC8185400 DOI: 10.1167/iovs.62.7.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 05/03/2021] [Indexed: 12/04/2022] Open
Abstract
Purpose Stimulation of Sigma 1 Receptor (S1R) is neuroprotective in retina and optic nerve. S1R is expressed in both neurons and glia. The purpose of this work is to evaluate the ability of S1R to modulate reactivity responses of optic nerve head astrocytes (ONHAs) by investigating the extent to which S1R activation alters ONHA reactivity under conditions of ischemic cellular stress. Methods Wild type (WT) and S1R knockout (KO) ONHAs were derived and treated with vehicle or S1R agonist, (+)-pentazocine ((+)-PTZ). Cells were subjected to six hours of oxygen glucose deprivation (OGD) followed by 18 hours of re-oxygenation (OGD/R). Astrocyte reactivity responses were measured. Molecules that regulate ONHA reactivity, signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa B (NF-kB), were evaluated. Results Baseline glial fibrillary acidic protein (GFAP) levels were increased in nonstressed KO ONHAs compared with WT cultures. Baseline cellular migration was also increased in nonstressed KO ONHAs compared with WT. Treatment with (+)-PTZ increased cellular migration in nonstressed WT ONHAs but not in KO ONHAs. Exposure of both WT and KO ONHAs to ischemia (OGD/R), increased GFAP levels and cellular proliferation. However, (+)-PTZ treatment of OGD/R-exposed ONHAs enhanced GFAP levels, cellular proliferation, and cellular migration in WT but not KO cultures. The (+)-PTZ treatment of WT ONHAs also enhanced the OGD/R-induced increase in cellular pSTAT3 levels. However, treatment of WT ONHAs with (+)-PTZ abrogated the OGD/R-induced rise in NF-kB(p65) activation. Conclusions Under ischemic stress conditions, S1R activation enhanced ONHA reactivity characteristics. Future studies should address effects of these responses on RGC survival.
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Affiliation(s)
- Jing Zhao
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Graydon Gonsalvez
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
| | - Manuela Bartoli
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Barbara A. Mysona
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Sylvia B. Smith
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
| | - Kathryn E. Bollinger
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- Culver Vision Discovery Institute, Augusta, Georgia, United States
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Jasien JV, Fazio MA, Samuels BC, Johnston JM, Downs JC. Quantification of Translaminar Pressure Gradient (TLPG) With Continuous Wireless Telemetry in Nonhuman Primates (NHPs). Transl Vis Sci Technol 2020; 9:18. [PMID: 33240571 PMCID: PMC7671865 DOI: 10.1167/tvst.9.12.18] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/10/2020] [Indexed: 12/21/2022] Open
Abstract
Purpose Recent retrospective clinical and animal studies suggest that cerebrospinal fluid pressure (CSFP) is important in glaucoma pathogenesis. Intraocular pressure (IOP) and CSFP are the driving components of translaminar pressure (TLP = IOP - CSFP), which acts across the lamina cribrosa (LC) thickness to create the translaminar pressure gradient (TLPG = TLP/LC thickness). Methods We developed an implantable wireless telemetry system based on a small piezoelectric sensor with low temporal drift. IOP, measured in the anterior chamber, and intracranial pressure (ICP), measured in the brain parenchyma (as a surrogate for CSFP) were measured at 200 Hz in three male rhesus macaques (nonhuman primates, NHPs) on a 10% duty cycle (15 seconds of every 150-second period). Three-dimensional LC thickness was autosegmented as the mean thickness of the visible hyperreflective band in 48 radial spectral-domain optical coherence tomography b-scans centered on the optic nerve head. Results Results indicated the rank order of IOP, ICP, TLP, and TLPG for waking, sleeping, and 24-hour periods averaged across all days. NHP 150110 had the highest IOP and ICP in all periods; however, it had the lowest TLPG in all periods due to its relatively thick LC. The other two NHPs showed similar shifts in the rank order of possible glaucoma risk factors. Conclusions IOP is the only modifiable and readily measurable pressure-based risk factor for glaucoma. However, other potential risk factors such as ICP, TLP, and TLPG, as well as their rank-order patterns, differed compared to IOP across subjects, demonstrating that a comprehensive view of relevant risk factors is warranted. Translational Relevance Future studies should consider including CSFP, TLP, and TLPG in addition to IOP as potential risk factors when assessing eye-specific glaucoma susceptibility.
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Affiliation(s)
- Jessica V Jasien
- Vision Science Graduate Program, School of Optometry, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Massimo A Fazio
- Department of Ophthalmology and Visual Sciences, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brian C Samuels
- Department of Ophthalmology and Visual Sciences, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - James M Johnston
- Department of Neurosurgery, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, School of Medicine, The University of Alabama at Birmingham, Birmingham, AL, USA
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Pappelis K, Choritz L, Jansonius NM. Microcirculatory model predicts blood flow and autoregulation range in the human retina: in vivo investigation with laser speckle flowgraphy. Am J Physiol Heart Circ Physiol 2020; 319:H1253-H1273. [PMID: 32986964 DOI: 10.1152/ajpheart.00404.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this study, we mathematically predict retinal vascular resistance (RVR) and retinal blood flow (RBF), we test predictions using laser speckle flowgraphy (LSFG), we estimate the range of vascular autoregulation, and we examine the relationship of RBF with the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). Fundus, optical coherence tomography (OCT), and OCT-angiography images, systolic/diastolic blood pressure (SBP/DBP), and intraocular pressure (IOP) measurements were obtained from 36 human subjects. We modeled two circulation markers (RVR and RBF) and estimated individualized lower/higher autoregulation limits (LARL/HARL), using retinal vessel calibers, fractal dimension, perfusion pressure, and population-based hematocrit values. Quantitative LSFG waveforms were extracted from vessels of the same eyes, before and during IOP elevation. LSFG metrics explained most variance in RVR (R2 = 0.77/P = 6.9·10-9) and RBF (R2 = 0.65/P = 1.0·10-6), suggesting that the markers strongly reflect blood flow physiology. Higher RBF was associated with thicker RNFL (P = 4.0·10-4) and GCC (P = 0.003), thus also verifying agreement with structural measurements. LARL was at SBP/DBP of 105/65 mmHg for the average subject without arterial hypertension and at 115/75 mmHg for the average hypertensive subject. Moreover, during IOP elevation, changes in RBF were more pronounced than changes in RVR. These observations physiologically imply that healthy subjects are already close to LARL, thus prone to hypoperfusion. In conclusion, we modeled two clinical markers and described a novel method to predict individualized autoregulation limits. These findings could improve understanding of retinal perfusion and pave the way for personalized intervention decisions, when treating patients with coexisting ophthalmic and cardiovascular pathologies.NEW & NOTEWORTHY We describe and test a new approach to quantify retinal blood flow, based on standard clinical examinations and imaging techniques, linked together with a physiological model. We use these findings to generate individualized estimates of the autoregulation range. We provide evidence that healthy subjects are closer to the lower autoregulation limit than thought before. This suggests that some retinas are less prepared to withstand hypoperfusion, even after small intraocular pressure rises or blood pressure drops.
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Affiliation(s)
- Konstantinos Pappelis
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
| | - Lars Choritz
- University Eye Clinic, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Nomdo M Jansonius
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands
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10
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Chuangsuwanich T, Hung PT, Wang X, Liang LH, Schmetterer L, Boote C, Girard MJA. Morphometric, Hemodynamic, and Biomechanical Factors Influencing Blood Flow and Oxygen Concentration in the Human Lamina Cribrosa. Invest Ophthalmol Vis Sci 2020; 61:3. [PMID: 32271886 PMCID: PMC7401712 DOI: 10.1167/iovs.61.4.3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose We developed a combined biomechanical and hemodynamic model of the human eye to estimate blood flow and oxygen concentration within the lamina cribrosa (LC) and rank the factors that influence LC oxygen concentration. Methods We generated 5000 finite-element eye models with detailed microcapillary networks of the LC and computed the oxygen concentration of the lamina retinal ganglion cell axons. For each model, we varied the intraocular pressure (IOP) from 10 mm Hg to 55 mm Hg in 5-mm Hg increments, the cerebrospinal fluid pressure (13 ± 2 mm Hg), cup depth (0.2 ± 0.1 mm), scleral stiffness (±20% of the mean values), LC stiffness (0.41 ± 0.2 MPa), LC radius (1.2 ± 0.12 mm), average LC pore size (5400 ± 2400 µm2), the microcapillary arrangement (radial, isotropic, or circumferential), and perfusion pressure (50 ± 9 mm Hg). Blood flow was assumed to originate from the LC periphery and drain via the central retinal vein. Finally, we performed linear regressions to rank the influence of each factor on the LC tissue oxygen concentration. Results LC radius and perfusion pressure were the most important factors in influencing the oxygen concentration of the LC. IOP was another important parameter, and eyes with higher IOP had higher compressive strain and slightly lower oxygen concentration. In general, superior–inferior regions of the LC had significantly lower oxygen concentration than the nasal–temporal regions, resulting in an hourglass pattern of oxygen deficiency. Conclusions To the best of our knowledge, this study is the first to implement a comprehensive hemodynamical model of the eye that accounts for the biomechanical forces and morphological parameters of the LC. The results provide further insight into the possible relationship of biomechanical and vascular pathways leading to ischemia-induced optic neuropathy.
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11
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Gardiner SK, Cull G, Fortune B, Wang L. Increased Optic Nerve Head Capillary Blood Flow in Early Primary Open-Angle Glaucoma. Invest Ophthalmol Vis Sci 2019; 60:3110-3118. [PMID: 31323681 PMCID: PMC6645706 DOI: 10.1167/iovs.19-27389] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Blood flow in the optic nerve head (ONH) is known to be reduced in eyes with advanced glaucoma. However, experimental results from non-human primates suggest an initial increase in ONH blood flow at the earliest stages of damage. This study assesses flow and pulsatile hemodynamics across a range of severities to test the hypothesis that this also occurs in human glaucoma. Methods Laser speckle flowgraphy was used to measure average mean blur rate (MBRave) within ONH tissue (a correlate of capillary blood flow) and the pulsatile waveform in 93 eyes with functional loss and 74 glaucoma suspect/fellow eyes without functional loss. These were compared against results from 92 healthy control eyes. Parameters produced by the instrument's software were age-corrected, then compared between groups using generalized estimating equation models. Results The mean MBRave in the control eyes was 12.5 units. In glaucoma suspect/fellow eyes, the mean was 16.4 units, higher with P < 0.0001. In eyes with functional loss, the mean was 13.8 units, lower than eyes without functional loss with P < 0.0001, although still higher than control eyes with P = 0.0096. Analysis of the pulsatile waveform suggested that the deceleration in flow as it approaches its maximum across the cardiac cycle was delayed in glaucoma. Conclusions Blood flow within ONH capillaries was higher in glaucoma suspect eyes than in healthy controls. It was less elevated in eyes that had developed functional loss. The mechanisms causing these changes and their relation to concurrent changes in pulsatile hemodynamics remain under investigation.
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Affiliation(s)
- Stuart K Gardiner
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
| | - Grant Cull
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
| | - Lin Wang
- Devers Eye Institute, Legacy Health, Portland, Oregon, United States
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12
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Wang X, Chen J, Kong X, Sun X. Immediate Changes in Peripapillary Retinal Vasculature after Intraocular Pressure Elevation -an Optical Coherence Tomography Angiography Study. Curr Eye Res 2019; 45:749-756. [PMID: 31751156 DOI: 10.1080/02713683.2019.1695843] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: To investigate changes in peripapillary retinal vessel density after acute intraocular pressure (IOP) elevation caused by laser peripheral iridotomy (LPI) in primary angle-closure suspects (PACS) by optical coherence tomography angiography (OCTA).Materials and Methods: Ninety-seven participants with PACS were included in this cross-sectional observational study. OCTA and IOP measurement were performed at baseline and 1 h after LPI. PACS eyes were further divided into three groups according to IOP increase 1 h after LPI (group 1 = IOP elevation <5 mmHg, 42eyes; group 2 = IOP elevation ≥5 mmHg and <10 mmHg, 34 eyes; group 3 = IOP elevation ≥10 mmHg, 21eyes). The changes of vessel density in radial peripapillary capillary (RPC) and entire retina were compared among groups.Results: When all eyes were included, the vessel density of RPC and entire retina 1 h after LPI were significantly decreased compared to the baseline (RPC: 64.5 ± 7.9 vs.67.8 ± 6.8, P < .001; retina: 86.3 ± 4.6 vs.88.3 ± 3.8, P < .001). There were significant differences among the three groups in the RPC and retinal vessel density at 1 h after LPI (RPC: 67.4 ± 7.3 vs. 63.2 ± 7.6 vs. 60.9 ± 7.5, P = .003; retinal: 87.7 ± 4.0 vs. 85.8 ± 4.5 vs. 84.3 ± 5.2, P = .015). In group 2 with an increased IOP from 5 mmHg to 10 mmHg, the reduction of vessel density in the RPC was more significant than that of the entire retina (RPC vs. retina: 7.1 ± 10.0% vs. 3.0 ± 4.4%, P = .006).Conclusions: LPI-induced IOP spikes resulted in a decrease in retina vessel density with PACS eyes by OCTA. The reduction of RPC vessel density was more significant than that of the entire retina in the subgroup of IOP increase from 5 to 10 mmHg. This suggests that vessel density in RPC was more sensitive to IOP increase than that of the entire retina in the peripapillary area.
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Affiliation(s)
- Xiaolei Wang
- Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Ministry of Health (Fudan University), and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Junyi Chen
- Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Ministry of Health (Fudan University), and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Xiangmei Kong
- Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Ministry of Health (Fudan University), and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Ministry of Health (Fudan University), and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
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13
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Kiyota N, Shiga Y, Ichinohasama K, Yasuda M, Aizawa N, Omodaka K, Honda N, Kunikata H, Nakazawa T. The Impact of Intraocular Pressure Elevation on Optic Nerve Head and Choroidal Blood Flow. Invest Ophthalmol Vis Sci 2019; 59:3488-3496. [PMID: 30025080 DOI: 10.1167/iovs.18-23872] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To use laser speckle flowgraphy (LSFG) to assess blood flow (BF) in the optic nerve head (ONH) tissue and choroid during elevated intraocular pressure (IOP). Methods This prospective study included 20 eyes of 20 healthy volunteers. The testing protocol had a baseline phase, two elevated IOP phases (+10 and +20 mm Hg), and a recovery phase. IOP was elevated by pushing against the eyelid with a novel tubular device attached to the LSFG apparatus. Measurement parameters in each phase included: LSFG-derived mean blur rate (MBR) and flow acceleration index (FAI); systemic parameters, and IOP. The % change against baseline was calculated for each phase. The protocol was repeated five times to calculate the coefficient of variation (CV) for % change MBR and to determine the effect of mydriasis on % change MBR. We compared % change MBR and FAI and evaluated the relationship between % change ocular perfusion pressure (OPP) and MBR in the choroid and ONH tissue. Results The % change MBR was highly reproducible (CV: 6.1-8.7%) and not affected by mydriasis (P = 0.57-0.96). The % change MBR and FAI were higher in the ONH tissue than choroid during IOP elevation (P = 0.04). The % change OPP and MBR showed positive linear correlations and two-segmental linear correlations in the choroid and ONH tissue, respectively (P < 0.01). Conclusion Hemodynamics during IOP elevation differ in the choroid and ONH tissue. LSFG enables highly reproducible assessment of the dynamic autoregulation of ocular BF in the ONH tissue.
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Affiliation(s)
- Naoki Kiyota
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yukihiro Shiga
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Kohei Ichinohasama
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Masayuki Yasuda
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Naoko Aizawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Kazuko Omodaka
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Naoto Honda
- Development Sec. 9, Medical Development Department, Eye Care Division, NIDEK Co., Ltd, Aichi, Japan
| | - Hiroshi Kunikata
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Development Sec. 9, Medical Development Department, Eye Care Division, NIDEK Co., Ltd, Aichi, Japan.,Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Miyagi, Japan.,Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Miyagi, Japan
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14
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Bata AM, Fondi K, Witkowska KJ, Werkmeister RM, Hommer A, Vass C, Resch H, Schmidl D, Popa‐Cherecheanu A, Chua J, Garhöfer G, Schmetterer L. Optic nerve head blood flow regulation during changes in arterial blood pressure in patients with primary open-angle glaucoma. Acta Ophthalmol 2019; 97:e36-e41. [PMID: 30218499 PMCID: PMC6492118 DOI: 10.1111/aos.13850] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/20/2018] [Indexed: 01/07/2023]
Abstract
PURPOSE Abnormal autoregulation of optic nerve head blood flow (ONHBF) has been postulated to play an important role in primary open-angle glaucoma (POAG). We used laser Doppler flowmetry (LDF) to estimate quantitatively the ONHBF and compared ONHBF autoregulation between glaucoma patients and healthy controls during isometric exercise. METHODS Forty patients with POAG and 40 healthy age- and sex-matched subjects underwent three periods of isometric exercise, each consisting of 2 min of handgripping. Optic nerve head blood flow (ONHBF) was measured continuously using LDF. Systemic blood pressure, intraocular pressure and ocular perfusion pressure were assessed in all participants. RESULTS Isometric exercise was associated with an increase in ocular perfusion pressure during all handgripping periods in both groups (p < 0.001). However, there was no change in ONHBF in either group. Three of the glaucoma patients and two of the healthy subjects showed a consistent 10% decrease in blood flow during isometric exercise, in spite of an increase in their blood pressure. This difference between groups was not significant (p = 0.61). Four other glaucoma subjects showed a consistent increase in blood flow of more than 10% during isometric exercise, whereas this was not seen in healthy subjects (p = 0.035). CONCLUSION This study suggests that abnormal ONHBF autoregulation is more often seen in patients with POAG than healthy control subjects. The relationship to the glaucoma disease process is currently unknown and requires further investigation.
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Affiliation(s)
- Ahmed M. Bata
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Klemens Fondi
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | | | - René M. Werkmeister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Anton Hommer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria,Department of OphthalmologySanatorium HeraViennaAustria
| | - Clemens Vass
- Department of OphthalmologyMedical University of ViennaViennaAustria
| | - Hemma Resch
- Department of OphthalmologyMedical University of ViennaViennaAustria
| | - Doreen Schmidl
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria,Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Alina Popa‐Cherecheanu
- Department of OphthalmologyEmergency University HospitalBucharestRomania,Carol Davila University of Medicine and PharmacyBucharestRomania
| | | | - Gerhard Garhöfer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Leopold Schmetterer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria,Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria,Singapore Eye Research InstituteSingaporeSingapore,Lee Kong School of MedicineNanyang Technological UniversitySingaporeSingapore,Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingaporeSingapore
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15
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Increase in the OCT angiographic peripapillary vessel density by ROCK inhibitor ripasudil instillation: a comparison with brimonidine. Graefes Arch Clin Exp Ophthalmol 2018. [PMID: 29520478 PMCID: PMC6006239 DOI: 10.1007/s00417-018-3945-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Purpose To assess the responses of the superficial peripapillary retinal vessel density (VD) and prelaminar flow index (PLFI) to topical Rho-assisted coiled-coil forming protein kinase (ROCK) inhibitor ripasudil and alpha-2 agonist brimonidine using optical coherence tomography angiography. Methods This is a prospective, non-randomized, comparative cohort study. We studied the response of optical coherence tomography angiography (OCTA) parameters to drugs in 24 eyes treated with ripasudil and 23 eyes treated with brimonidine at the Sensho-kai Eye Institute. After division by the signal strength (SS), we compared the responses of peripapillary VD/SS and PLFI/unit area (UA)/SS to topical eye drops in eyes with primary open-angle glaucoma (POAG) and ocular hypertension (OH). Results In the superficial peripapillary retina, VD/SS increased significantly in the ripasudil-treated eyes (12.5 ± 21.7%, P = 0.018), but not in the brimonidine-treated eyes (− 2.0 ± 13.8%, P = 0.484). In the deeper area of the optic disc, the changes in the PLFI/UA/SS in the brimonidine-treated eyes (+ 0.9 ± 8.9%, P = 1.00) and ripasudil-treated eyes (− 1.3 ± 8.5%, P = 0.241) were not significant. Multivariate discriminant analysis showed that the change in the peripapillary VD/SS was the most important parameter (P = 0.0186) for differentiating ripasudil- and brimonidine-treated eyes. Conclusions The topical ROCK inhibitor ripasudil enhanced the peripapillary VD in POAG and OH, whereas the alpha-2 agonist brimonidine did not. The PLFI did not respond to either drug. Electronic supplementary material The online version of this article (10.1007/s00417-018-3945-5) contains supplementary material, which is available to authorized users.
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16
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Tan B, MacLellan B, Mason E, Bizheva K. Structural, functional and blood perfusion changes in the rat retina associated with elevated intraocular pressure, measured simultaneously with a combined OCT+ERG system. PLoS One 2018; 13:e0193592. [PMID: 29509807 PMCID: PMC5839563 DOI: 10.1371/journal.pone.0193592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/14/2018] [Indexed: 02/07/2023] Open
Abstract
Acute elevation of intraocular pressure (IOP) to ischemic and non-ischemic levels can cause temporary or permanent changes in the retinal morphology, function and blood flow/blood perfusion. Previously, such changes in the retina were assessed separately with different methods in clinical studies and animal models. In this study, we used a combined OCT+ ERG system in combination with Doppler OCT and OCT angiography (OCTA) imaging protocols, in order to evaluate simultaneously and correlate changes in the retinal morphology, the retinal functional response to visual stimulation, and the retinal blood flow/blood perfusion, associated with IOP elevation to ischemic and non-ischemic levels in rats. Results from this study suggest that the inner retina responds faster to IOP elevation to levels greater than 30 mmHg with significant reduction of the total retinal blood flow (TRBF), decrease of the capillaries’ perfusion and reduction of the ON bipolar cells contribution to the ERG traces. Furthermore, this study showed that ischemic levels of IOP elevation cause an additional significant decrease in the ERG photoreceptor response in the posterior retina. Thirty minutes after IOP normalization, retinal morphology, blood flow and blood perfusion recovered to baseline values, while retinal function did not recover completely.
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Affiliation(s)
- Bingyao Tan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin MacLellan
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik Mason
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
| | - Kostadinka Bizheva
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
- Department of System Design Engineering, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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17
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Patel N, McAllister F, Pardon L, Harwerth R. The effects of graded intraocular pressure challenge on the optic nerve head. Exp Eye Res 2018; 169:79-90. [PMID: 29409880 DOI: 10.1016/j.exer.2018.01.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 01/27/2018] [Accepted: 01/30/2018] [Indexed: 12/21/2022]
Abstract
Intraocular pressure (IOP) is an important risk factor for glaucoma, and the response of the ONH and surrounding tissues to elevated IOP are often investigated to better understand pathophysiology. In vivo structure including that of the optic nerve head (ONH) and surrounding tissue of the eye are often assessed using optical coherence tomography (OCT). With advances in OCT technology, both large vessels and capillaries can be imaged non-invasively (OCT Angiography). Because a significant portion of retinal thickness is comprised of vasculature, the purpose of the current study was to investigate OCT structural and vascular changes in healthy non-human primate eyes with systematic graded increases and decreases in IOP. Six healthy animals with no previous experimental intervention were used. The pressure in the anterior chamber was adjusted from 10 mmHg to 60 mmHg and back to 10 mmHg in 10 mmHg steps every 10 min. Using optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, minimum rim width (MRW), Bruch's membrane opening (BMO) size and relative height, anterior lamina cribrosa surface (ALCS) depth, choroidal thickness, and angiography (OCTA) were quantified. With IOP challenge there were significant changes in all morphological measures quantified (p < 0.01) other than BMO size (p = 0.30) and RNFL thickness (p = 0.29). Specifically, the position of the BMO was sensitive to both an increase and decease in IOP. The inner retinal capillary density gradually decreased with increasing IOP, reaching statistical significance when pressure exceeded 50 mmHg, but returned when IOP was reduced. The average choroidal thickness around the ONH decreased for elliptical annuli 500-1000 μm and 1000-1500 μm, from the BMO, with increasing IOP (p < 0.01). For the 1000-1500 μm annulus, choroid thickness did not return to baseline with IOP reduction. Similarly, the MRW decreased with increase in IOP, but with pressure reduction did not return, and at the final 10 mmHg time point was thinner than at baseline (p < 0.01). The results from this experiment illustrate differences in ONH neural rim tissue, RNFL and vessel density changes with acute IOP challenge. Overall, vessel collapse could not completely account for changes in RNFL or ONH MRW thickness. The study supports the hypothesis neural rim compression may be an important part of IOP-induced damage.
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Affiliation(s)
- Nimesh Patel
- University of Houston, College of Optometry, 4901 Calhoun Road, Houston, TX 77204, USA.
| | - Faith McAllister
- University of Houston, College of Optometry, 4901 Calhoun Road, Houston, TX 77204, USA
| | - Laura Pardon
- University of Houston, College of Optometry, 4901 Calhoun Road, Houston, TX 77204, USA
| | - Ronald Harwerth
- University of Houston, College of Optometry, 4901 Calhoun Road, Houston, TX 77204, USA
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18
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Kosekahya P, Caglayan M, Unal O, Yuzbasioglu S, Koc M, Ucgul Atilgan C, Yulek F. Optic Nerve Head Elastometry in Both Eyes of Patients with Unilateral Non-arteritic Anterior Ischaemic Optic Neuropathy - May It Be a Novel Aspect of the Pathogenesis? Neuroophthalmology 2017; 42:222-228. [PMID: 30042792 DOI: 10.1080/01658107.2017.1397702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 12/21/2022] Open
Abstract
In this prospective study, the biomechanical properties of optic nerve head (ONH) and cornea in both eyes of patients with non-arteritic anterior ischaemic optic neuropathy and healthy control eyes were investigated. ONH elastometry was measured with real-time elastography, and corneal elastometry was measured with ocular response analyser. Elastometry of cornea and ONH was lower in both eyes of patients with unilateral non-arteritic ischaemic optic neuropathy than in healthy control eyes. The role of these biomechanical differences in the pathogenesis of non-arteritic ischaemic optic neuropathy should be investigated further.
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Affiliation(s)
- Pinar Kosekahya
- Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - Mehtap Caglayan
- Department of Ophthalmology, Mardin State Hospital, Mardin, Turkey
| | - Ozlem Unal
- Department of Radiology, Ataturk Training and Research Hospital, Ankara, Turkey
| | - Sema Yuzbasioglu
- Department of Ophthalmology, Ataturk Training and Research Hospital, Ankara, Turkey
| | - Mustafa Koc
- Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | | | - Fatma Yulek
- Department of Ophthalmology, Yildirim Beyazit University Ataturk Research and Training Hospital, Ankara, Turkey
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19
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Witkowska KJ, Bata AM, Calzetti G, Luft N, Fondi K, Wozniak PA, Schmidl D, Bolz M, Popa-Cherecheanu A, Werkmeister RM, Garhöfer G, Schmetterer L. Optic nerve head and retinal blood flow regulation during isometric exercise as assessed with laser speckle flowgraphy. PLoS One 2017; 12:e0184772. [PMID: 28898284 PMCID: PMC5595424 DOI: 10.1371/journal.pone.0184772] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/30/2017] [Indexed: 12/20/2022] Open
Abstract
The aim of the present study was to investigate regulation of blood flow (BF) in the optic nerve head (ONH) and a peripapillary region (PPR) during an isometric exercise-induced increase in ocular perfusion pressure (OPP) using laser speckle flowgraphy (LSFG) in healthy subjects. For this purpose, a total of 27 subjects was included in this study. Mean blur rate in tissue (MT) was measured in the ONH and in a PPR as well as relative flow volume (RFV) in retinal arteries (ART) and veins (VEIN) using LSFG. All participants performed isometric exercise for 6 minutes during which MT and mean arterial pressure were measured every minute. From these data OPP and pressure/flow curves were calculated. Isometric exercise increased OPP, MTONH and MTPRR. The relative increase in OPP (78.5 ± 19.8%) was more pronounced than the increase in BF parameters (MTONH: 18.1 ± 7.7%, MTPRR: 21.1 ± 8.3%, RFVART: 16.5 ±12.0%, RFVVEIN: 17.7 ± 12.4%) indicating for an autoregulatory response of the vasculature. The pressure/flow curves show that MTONH, MTPRR, RFVART, RFVVEIN started to increase at OPP levels of 51.2 ± 2.0%, 58.1 ± 2.4%, 45.6 ± 1.9% and 45.6 ± 1.9% above baseline. These data indicate that ONHBF starts to increase at levels of approx. 50% increase in OPP: This is slightly lower than the values we previously reported from LDF data. Signals from the PPR may have input from both, the retina and the choroid, but the relative contribution is unknown. In addition, retinal BF appears to increase at slightly lower OPP values of approximately 45%. LSFG may be used to study ONH autoregulation in diseases such as glaucoma. Trial Registration: ClinicalTrials.gov NCT02102880
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Affiliation(s)
| | - Ahmed M. Bata
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Nikolaus Luft
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Ophthalmology, Kepler University Hospital, Linz, Austria
| | - Klemens Fondi
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Piotr A. Wozniak
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Matthias Bolz
- Department of Ophthalmology, Kepler University Hospital, Linz, Austria
| | - Alina Popa-Cherecheanu
- Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
- Department of Ophthalmology, Emergency University Hospital, Bucharest, Romania
| | - René M. Werkmeister
- 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
| | - 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
- Singapore Eye Research Institute, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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20
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Abstract
PURPOSE To examine the association between retinal arteriolar caliber and lumen, retinal sensitivity (RS), and retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes with single-hemifield loss. METHODS We conducted a prospective, nonrandomized, case-control study of 20 eyes of 20 patients with glaucoma with visual field damage confined to a single hemifield. The control group was composed of 20 eyes of 20 normal subjects. For all the eyes, we performed optical coherence tomography to assess the RNFL and standard automated perimetry to evaluate RS. External and internal arteriolar diameters were assessed in vivo using scanning laser Doppler flowmetry. RESULTS The RNFL was significantly thinner in glaucomatous eyes than in normal eyes (p < 0.001). In glaucomatous eyes, a positive correlation between sectorial RNFL thickness and the corresponding external and internal arteriolar diameters was found (r = 0.43, p = 0.05; r = 0.63, p = 0.003, respectively). The internal arteriolar diameter significantly correlated with RS in the corresponding abnormal hemifield (r = 0.44, p = 0.04). Compared with the normal hemifield, the internal arteriolar diameter, RNFL thickness, and RS were significantly reduced, whereas the external arteriolar diameter was unchanged in the abnormal hemifield. CONCLUSIONS In glaucomatous eyes with single-hemifield damage, attenuation of retinal vessels was associated with a thinner RNFL and reduced RS. Moreover, a narrower lumen with increased wall-to-lumen ratio was found in the abnormal hemifield, supporting the hypothesis that vessel narrowing is likely secondary to a lower demand for blood flow in the glaucomatous areas of the retina.
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21
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Yang H, Reynaud J, Lockwood H, Williams G, Hardin C, Reyes L, Stowell C, Gardiner SK, Burgoyne CF. The connective tissue phenotype of glaucomatous cupping in the monkey eye - Clinical and research implications. Prog Retin Eye Res 2017; 59:1-52. [PMID: 28300644 PMCID: PMC5603293 DOI: 10.1016/j.preteyeres.2017.03.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 02/14/2017] [Accepted: 03/06/2017] [Indexed: 10/20/2022]
Abstract
In a series of previous publications we have proposed a framework for conceptualizing the optic nerve head (ONH) as a biomechanical structure. That framework proposes important roles for intraocular pressure (IOP), IOP-related stress and strain, cerebrospinal fluid pressure (CSFp), systemic and ocular determinants of blood flow, inflammation, auto-immunity, genetics, and other non-IOP related risk factors in the physiology of ONH aging and the pathophysiology of glaucomatous damage to the ONH. The present report summarizes 20 years of technique development and study results pertinent to the characterization of ONH connective tissue deformation and remodeling in the unilateral monkey experimental glaucoma (EG) model. In it we propose that the defining pathophysiology of a glaucomatous optic neuropathy involves deformation, remodeling, and mechanical failure of the ONH connective tissues. We view this as an active process, driven by astrocyte, microglial, fibroblast and oligodendrocyte mechanobiology. These cells, and the connective tissue phenomena they propagate, have primary and secondary effects on retinal ganglion cell (RGC) axon, laminar beam and retrolaminar capillary homeostasis that may initially be "protective" but eventually lead to RGC axonal injury, repair and/or cell death. The primary goal of this report is to summarize our 3D histomorphometric and optical coherence tomography (OCT)-based evidence for the early onset and progression of ONH connective tissue deformation and remodeling in monkey EG. A second goal is to explain the importance of including ONH connective tissue processes in characterizing the phenotype of a glaucomatous optic neuropathy in all species. A third goal is to summarize our current efforts to move from ONH morphology to the cell biology of connective tissue remodeling and axonal insult early in the disease. A final goal is to facilitate the translation of our findings and ideas into neuroprotective interventions that target these ONH phenomena for therapeutic effect.
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Affiliation(s)
- Hongli Yang
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Juan Reynaud
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Howard Lockwood
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Galen Williams
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Christy Hardin
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Luke Reyes
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Cheri Stowell
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Stuart K Gardiner
- Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States
| | - Claude F Burgoyne
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, United States; Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, United States.
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Liu J, Sun J, Diao Y, Deng A. Association of Electroencephalography (EEG) Power Spectra with Corneal Nerve Fiber Injury in Retinoblastoma Patients. Med Sci Monit 2016; 22:3135-9. [PMID: 27592207 PMCID: PMC5021016 DOI: 10.12659/msm.897050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Background In our clinical experience we discovered that EEG band power may be correlated with corneal nerve injury in retinoblastoma patients. This study aimed to investigate biomarkers obtained from electroencephalography (EEG) recordings to reflect corneal nerve injury in retinoblastoma patients. Material/Methods Our study included 20 retinoblastoma patients treated at the Department of Ophthalmology, Affiliated Hospital of Weifang Medical University between 2010 and 2014. Twenty normal individuals were included in the control group. EEG activity was recorded continuously with 32 electrodes using standard EEG electrode placement for detecting EEG power. A cornea confocal microscope was used to examine corneal nerve injury in retinoblastoma patients and normal individuals. Spearman rank correlation analysis was used to analyze the correlation between corneal nerve injury and EEG power changes. The sensitivity and specificity of changed EEG power in diagnosis of corneal nerve injury were also analyzed. Results The predominantly slow EEG oscillations changed gradually into faster waves in retinoblastoma patients. The EEG pattern in retinoblastoma patients was characterized by a distinct increase of delta (P<0.01) and significant decrease of theta power P<0.05). Corneal nerves were damaged in corneas of retinoblastoma patients. Corneal nerve injury was positively correlated with delta EEG spectra power and negatively correlated with theta EEG spectra power. The diagnostic sensitivity and specificity by compounding in the series were 60% and 67%, respectively. Conclusions Changes in delta and theta of EEG appear to be associated with occurrence of corneal nerve injury. Useful information can be provided for evaluating corneal nerve damage in retinoblastoma patients through analyzing EEG power bands.
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Affiliation(s)
- Jianliang Liu
- Department of Ophthalmology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China (mainland)
| | - Juanjuan Sun
- Department of Ophthalmology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China (mainland)
| | - Yumei Diao
- Department of Ophthalmology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China (mainland)
| | - Aijun Deng
- Department of Ophthalmology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China (mainland)
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Cull G, Told R, Burgoyne CF, Thompson S, Fortune B, Wang L. Compromised Optic Nerve Blood Flow and Autoregulation Secondary to Neural Degeneration. Invest Ophthalmol Vis Sci 2016; 56:7286-92. [PMID: 26551332 DOI: 10.1167/iovs.15-17879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To test the hypothesis that optic nerve head (ONH) blood flow (BF) and autoregulation compromise are consequences of optic nerve degeneration induced by surgical optic nerve transection (ONT). METHODS In both eyes of five nonhuman primates, peripapillary retinal nerve fiber layer thickness (RNFLT) was measured by spectral-domain optical coherence tomography. Optic nerve head BF and dynamic autoregulation responses to a rapid manometric IOP increase (from 10-40 mm Hg) were measured by Laser Speckle Flowgraphy. The measurements were conducted every 10 to 15 days before and after unilateral ONT. Post-ONT measurements were repeated until RNFLT in the ONT eye was reduced by more than 40% of baseline value. RESULTS After ONT, RNFLT, and ONH BF progressively declined over time (P < 0.0001 and P = 0.02, respectively). Longitudinal changes between the two were highly correlated (P < 0.0001). When data was grouped by test session, the first significant decreases for RNFLT and BF were found 13 ± 0.8 and 24 ± 3.2 days post ONT, respectively (P < 0.05, both). At the final time point (55 ± 0.5 days post ONT), RNFLT, and BF were reduced by 44% ± 2.0% and 38 ± 5.0% from baseline, respectively. Dynamic autoregulation analysis showed marginal increased response time in post-ONT eyes (P = 0.05). Control eyes showed no longitudinal changes for any parameter. CONCLUSIONS The close association between RNFLT loss and ONH BF decrease following optic nerve degeneration demonstrated a clear cause and effect relationship. Increased BF response time appears to be a sign of dynamic autoregulation dysfunction in this ONT model.
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Affiliation(s)
- Grant Cull
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
| | - Reinhard Told
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Claude F Burgoyne
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
| | - Simon Thompson
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
| | - Lin Wang
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
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24
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Quill B, Henry E, Simon E, O'Brien CJ. Evaluation of the Effect of Hypercapnia on Vascular Function in Normal Tension Glaucoma. BIOMED RESEARCH INTERNATIONAL 2015; 2015:418159. [PMID: 26557667 PMCID: PMC4628756 DOI: 10.1155/2015/418159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/26/2015] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Altered ocular perfusion and vascular dysregulation have been reported in glaucoma. The aim of this paper was to evaluate the vascular response to a hypercapnic stimulus. METHODS Twenty normal tension glaucoma (NTG) patients and eighteen age- and gender-matched controls had pulsatile ocular blood flow (POBF) measurements, systemic cardiovascular assessment, and laser Doppler digital blood flow (DBF) assessed. Measurements were taken at baseline, after 10-minutes rest, in the stable sitting and supine positions and following induction and stabilization of hypercapnia, which induced a 15% increase in end-tidal pCO2. The POBF response to hypercapnia was divided into high (>20%) and low responders (<20%). RESULTS 65% of NTG patients had a greater than 41% increase in POBF following CO2 rebreathing (high responders). These high responders had a lower baseline POBF, lower baseline DBF, and a greater DBF response to thermal stimulus. CONCLUSION NTG patients that have a greater than 20% increase in POBF after a hypercapnic stimulus have lower baseline POBF and DBF values. This suggests that there is impaired regulation of blood flow in a significant subgroup of NTG patients. This observation may reflect a generalised dysfunction of the vascular endothelium.
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Affiliation(s)
- B. Quill
- UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - E. Henry
- Princess Alexandra Eye Pavilion, Edinburgh, UK
| | - E. Simon
- Princess Alexandra Eye Pavilion, Edinburgh, UK
| | - C. J. O'Brien
- UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
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25
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The non-human primate experimental glaucoma model. Exp Eye Res 2015; 141:57-73. [PMID: 26070984 DOI: 10.1016/j.exer.2015.06.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/03/2015] [Accepted: 06/06/2015] [Indexed: 01/05/2023]
Abstract
The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.
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Fortune B. In vivo imaging methods to assess glaucomatous optic neuropathy. Exp Eye Res 2015; 141:139-53. [PMID: 26048475 DOI: 10.1016/j.exer.2015.06.001] [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: 03/08/2015] [Revised: 05/13/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
Abstract
The goal of this review is to summarize the most common imaging methods currently applied for in vivo assessment of ocular structure in animal models of experimental glaucoma with an emphasis on translational relevance to clinical studies of the human disease. The most common techniques in current use include optical coherence tomography and scanning laser ophthalmoscopy. In reviewing the application of these and other imaging modalities to study glaucomatous optic neuropathy, this article is organized into three major sections: 1) imaging the optic nerve head, 2) imaging the retinal nerve fiber layer and 3) imaging retinal ganglion cell soma and dendrites. The article concludes with a brief section on possible future directions.
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Affiliation(s)
- Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, 1225 NE Second Avenue, Portland, OR 97232, USA.
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Downs JC. Optic nerve head biomechanics in aging and disease. Exp Eye Res 2015; 133:19-29. [PMID: 25819451 DOI: 10.1016/j.exer.2015.02.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 12/31/2014] [Accepted: 02/12/2015] [Indexed: 11/28/2022]
Abstract
This nontechnical review is focused upon educating the reader on optic nerve head biomechanics in both aging and disease along two main themes: what is known about how mechanical forces and the resulting deformations are distributed in the posterior pole and ONH (biomechanics) and what is known about how the living system responds to those deformations (mechanobiology). We focus on how ONH responds to IOP elevations as a structural system, insofar as the acute mechanical response of the lamina cribrosa is confounded with the responses of the peripapillary sclera, prelaminar neural tissues, and retrolaminar optic nerve. We discuss the biomechanical basis for IOP-driven changes in connective tissues, blood flow, and cellular responses. We use glaucoma as the primary framework to present the important aspects of ONH biomechanics in aging and disease, as ONH biomechanics, aging, and the posterior pole extracellular matrix (ECM) are thought to be centrally involved in glaucoma susceptibility, onset and progression.
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Affiliation(s)
- J Crawford Downs
- Department of Ophthalmology, University of Alabama at Birmingham School of Medicine, 1670 University Blvd., VH 390A, Birmingham, AL 35294, USA.
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28
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Jones A, Kaplowitz K, Saeedi O. Autoregulation of optic nerve head blood flow and its role in open-angle glaucoma. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/17469899.2014.975796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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