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Journal ArticleDOI

Blood flow rate in the microvasculature of the optic nerve head in primary open angle glaucoma. A new approach.

01 May 1994-Survey of Ophthalmology (Elsevier)-Vol. 38
TL;DR: The results showed that in POAG patients optic nerve blood velocity was reduced and that the aggregability of the RBCs was increased, and the data suggest that deformability ofTheRBCs is impaired in glaucoma.
About: This article is published in Survey of Ophthalmology.The article was published on 1994-05-01. It has received 36 citations till now. The article focuses on the topics: Blood viscosity & Optic nerve.
Citations
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Journal ArticleDOI
TL;DR: Additional research is required, particularly in characterizing the role of the three nitric oxide synthase isoforms in the control of ocular perfusion, to implement this concept into the clinical management ofOcular diseases.

185 citations

Journal ArticleDOI
TL;DR: Although data are lacking for glaucoma, endothelial dysfunction may provide an attractive target for therapeutic intervention in open‐angle glau coma and other vascular disorders of the eye.
Abstract: Glaucoma is a group of ocular diseases characterized by optic neuropathy associated with loss of the retinal nerve fibre layer and re-modelling of the optic nerve head, and a subsequent particular pattern of visual field loss. Increased intraocular pressure is the most important risk factor for the disease, but the pathogenesis of glaucoma is not monofactorial. Among other factors, ischaemia and vascular dysregulation have been implicated in the mechanisms underlying glaucoma. The vascular endothelium plays an important role in the regulation of ocular blood flow and pathological alterations of vascular endothelial cells may induce ischaemia and dysregulation. The present review summarizes our current evidence of endothelial dysfunction in glaucoma. This is of interest because endothelial dysfunction is a good prognostic factor for progression in several diseases. Although such data are lacking for glaucoma, endothelial dysfunction may provide an attractive target for therapeutic intervention in open-angle glaucoma and other vascular disorders of the eye.

182 citations


Cites background from "Blood flow rate in the microvascula..."

  • ...This is supported by evidence of functional abnormalities in both the ocular (reduced blood flow velocity; increased resistance) (Harris et al. 1994; Butt et al. 1997) and systemic (reduced digital blood flow) (Drance et al. 1988; Gasser & Flammer 1991) circulations of patients with NTG....

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Journal ArticleDOI
TL;DR: It is suggested that glaucoma patients tend to have less blood volume, flow, and velocity in the lamina cribrosa and upper temporal peripapillary retina.

152 citations

Journal ArticleDOI
TL;DR: The results in POAG patients and NPG patients showed that their optic nerve blood flow velocity was reduced and that the aggregability of the RBCs was increased, which supports the hypothesis of a vasogenic mechanism that could impair the optic nerve in glaucoma patients.
Abstract: Optic disc blood flow velocity was measured in healthy patients, those with primary open angle glaucoma (POAG), and patients with normal pressure glaucoma (NPG). The velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head (ONH) has been measured with a laser Doppler velocimeter (LDV), and blood viscosity has been evaluated notably by determining the aggregability of the RBCs with an erythroaggregameter. Our results in POAG patients and NPG patients showed that their optic nerve blood flow velocity was reduced and that the aggregability of the RBCs was increased. The hyperaggregability of the erythrocytes is responsible for the increase of the local viscosity in the papillary capillary network. These haemodynamic modifications observed in patients with glaucoma support the hypothesis of a vasogenic mechanism that could impair the optic nerve in glaucoma patients.

138 citations

Journal ArticleDOI
TL;DR: C Chronic IOP elevation causes significant ONH BF decreases in the EG model and the high correlation between the BF reduction measured by LSFG and the microsphere method provides evidence that the L SFG is capable of assaying BF for a critical deep ONH region.
Abstract: PURPOSE To characterize optic nerve head (ONH) blood flow (BF) changes in nonhuman primate experimental glaucoma (EG) using laser speckle flowgraphy (LSFG) and the microsphere method and to evaluate the correlation between the two methods. METHODS EG was induced in one eye each of 9 rhesus macaques by laser treatment to the trabecular meshwork. Prior to lasering and following onset of intraocular pressure (IOP) elevation, retinal never fiber layer thickness (RNFLT) and ONH BF were measured biweekly by spectral-domain optical coherence tomography and LSFG, respectively, until RNFLT loss was approximately 40% in the EG eye. Final BF was measured by LSFG and by the microsphere method in the anterior ONH (MS-BF(ANT)), posterior ONH (MS-BF(POST)), and peripapillary retina (MS-BF(PP)). RESULTS Baseline RNFLT and LSFG-BF showed no difference between the two eyes (P = 0.69 and P = 0.43, respectively, paired t-test). Mean (± SD) IOP was 30 ± 6 mm Hg in EG eyes and 13 ± 2 mm Hg in control eyes (P < 0.001). EG eye RNFLT and LSFG-BF were reduced by 42 ± 16% (P < 0.0001) and 22 ± 13% (P = 0.003), respectively, at the final time point. EG eye MS-BF(ANT), MS-BF(POST), and MS-BF(PP) were reduced by 41 ± 17% (P < 0.001), 22 ± 34% (P = 0.06), and 30 ± 12% (P = 0.001), respectively, compared with the control eyes. Interocular ONH LSFG-BF differences significantly correlated to that measured by the microsphere method (R(2) = 0.87, P < 0.001). CONCLUSIONS Chronic IOP elevation causes significant ONH BF decreases in the EG model. The high correlation between the BF reduction measured by LSFG and the microsphere method provides evidence that the LSFG is capable of assaying BF for a critical deep ONH region.

132 citations

References
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Journal ArticleDOI
Shu Chien1
22 May 1970-Science
TL;DR: The viscosity of suspensions of human erythrocytes was measured over a wide range of shear rates, and the macrorheological data were correlated with the micror heological behavior of ery throatcytes and rigid particles.
Abstract: The viscosity of suspensions of human erythrocytes (normal cells in plasma, normal cells in Ringer's solution containing albumin, and hardened cells in Ringer's solution containing albumin) was measured over a wide range of shear rates, and the macrorheological data were correlated with the microrheological behavior of erythrocytes and rigid particles. The formation of rouleaux increases the effective volume of erythrocytes as a result of (i) the increase in axial ratio and (ii) the limitation of deformation of individual erythrocytes. The effective cell volume is the fundamental determinant of blood viscosity.

386 citations

Book
01 Apr 1987
TL;DR: The results show clear trends in prognosis for Glaucoma patients with prior history of central giant cell granuloma, and these results are consistent with those of previous studies of this type.
Abstract: Experimental Modulation of the Uveal Vasculature- The Response of the Meshwork Cells to Adrenergic Agents and Their Antagonists- In Vitro Correlates of Glucocorticoid Effects on Intraocular Pressure- In Vitro Electrophysiology of the Ciliary Epithelium- The Ciliary Muscle and Nerves After Ciliary Ganglionectomy- In Vivo Measurement of Aqueous Flare in Human Eyes Diurnal Variation and Drug Effects- Electrophysiology of Cultured Retinal Ganglion Cells to Investigate Basic Mechanisms of Damage- The Anatomical Structure of the Normal and Glaucomatous Optic Nerve- The Biology of the Connective Tissue of the Human Optic Nerve Head- The Role of Panretinal Photocoagulation in Neovascular Glaucoma Associated with Central Retinal Vein Occlusion- Similarities of Total Disc Parameters for Glaucoma-like and Open-Angle Glaucoma Discs Matched by Optic Disc Area Size- Long-Term Observation of Glaucomatous Disk Changes- Vascular Reduction Following Axonal Damage in Glaucoma- Retinal Nerve Fiber Layer Thickness in Relation to Optic Disc Cup Shape in Open-Angle Glaucoma- Image Analysis of the Retinal Nerve Fiber Layer and Optic Nerve in Glaucoma- Direct Measurement of Retinal Nerve Fiber Layer Thickness- The Histopathology of the Optic Nerve in Low-Tension Glaucoma- Disc Hemorrhages in Low-Tension Glaucoma- Clinical Features and Systemic Background of Low-Tension Glaucoma- Some Characteristics of Glaucomatous Visual Field Loss- Motion and Form Perception in Glaucoma: Relationship to Sensitivity in the Visual Field- Short-Wavelength Visual Field Testing in Eyes with Primary Open-Angle Glaucoma- Assessment of Spatial and Temporal Modulation Transfer Functions in Early Glaucoma by Means of the Pattern Visual Evoked Potential- Ocular Pulsatile Blood Flow, Hypotensive Drugs, and Differential Light Sensitivity in Glaucoma- A Comparison of Treated and Untreated Glaucoma Suspects- Intraocular Pressure Control: Does it Protect the Visual Fields?- Prediction of Development of Glaucoma in Ocular Hypertensive Patients- The Case for Quality of Life Assessment in Glaucoma Clinical Trials- Lowering Intraocular Pressure Alters the Clinical Course of Glaucoma: Modifying Surgical Technique Can Change the Results- The Ocular Hypotensive Effect of Topically Applied Prostaglandins in Primates- The Effect of Glaucoma and Treatment of Glaucoma on the Quality of Life- Concepts in Ocular Drug Delivery- Fluorophotometric Studies on New Adrenergic Agents with Potential Use in Glaucoma- Multiple Dose, Dose Response Over 24 Hours Using the Novel, Topical Carbonic Anhydrase Inhibitor MK-927- The Effect of Sodium Hyaluronate on the Outcome of Trabeculectomy- The Blood Aqueous Barrier and Filtering Surgery- Pathophysiology of Molteno Implants- The Outcome of Molteno Implant Surgery- Preliminary Report of a Randomized Clinical Trial of Single Plate Versus Double Plate Molteno Implantation for Glaucomas in Aphakia and Pseudophakia- Immunophenotype of Human Trabecular Cells (Normal and Glaucomatous)

201 citations

Journal ArticleDOI
TL;DR: There is a marked inter-individual variation in the blood supply of the optic nerve head, and the various factors which produce this include variations in anatomical pattern of blood supply, the pattern of posterior ciliary artery (PCA) circulation (the main source of blood flow to the optic head), and the blood flow as discussed by the authors.
Abstract: There is no one standard pattern of the blood supply of the optic nerve head in all human eyes. There is a marked inter-individual variation in the blood supply of the optic nerve head, and the various factors which produce this include variations in (I) the anatomical pattern of blood supply, (II) the pattern of posterior ciliary artery (PCA) circulation (the main source of blood supply to the optic nerve head), and (III) the blood flow. The variations in the pattern of PCA circulation include the variations in (a) number of PCAs supplying an eye, (b) area of supply to the optic nerve head by each PCA, (c) location of the watershed zones between the various PCAs in relation to the optic nerve head, and (d) blood pressure in various PCAs as well as short PCAs. The variations in the blood flow in the optic nerve head can be produced by changes in (i) the intraocular pressure, (ii) mean blood pressure in the capillaries of the optic nerve head and (iii) peripheral vascular resistance. These variations are discussed in detail. A lack of appreciation of these complexities of the blood supply of the optic nerve head in health and disease is responsible for many of the current problems in the understanding of the role of vascular disturbances in anterior ischemic optic neuropathy, glaucoma, low-tension glaucoma and various ischemic disorders of the optic nerve head.

163 citations

Journal Article
TL;DR: Unless complicated by a defect in the macrocirculation, the biological significance of blood rheology seen under the aspects of entire organs is not primarily related to hemodynamics, but to diffusive transcapillary exchange.
Abstract: The normal rheological behavior of the red blood cells is prerequisite for the survival of the red cells and also for the functioning of microcirculation. Severe alterations of red cell deformability are incompatible with life. When compensated by anemia, even relatively severe rheological incompetence of individual red cells is tolerable. Functional loss of red cell deformability is widely known to occur under conditions of sustained hypoperfusion, and disseminated stagnation of blood in the paracapillary bed occurs. The resulting capillary occlusion does not necessarily reveal itself in grossly reduced flow rates or increased "total peripheral resistance," since it is compensated by shunting through microscopic anastomoses. The biological significance of the phenomenon of red cell aggregation (collateral loss of blood fluidity, "collateral blood viscidation") is related to hemodynamics only on the level of individual capillaries. Since the compensatory potentials of vasomotor factors at this level are also very high, the collateral viscidation is not only facilitated but by the same token partially compensated. Therefore, unless complicated by a defect in the macrocirculation, the biological significance of blood rheology seen under the aspects of entire organs is not primarily related to hemodynamics, but to diffusive transcapillary exchange. As a consequence of collateral blood viscidation, diffusion takes place under sub-optimal conditions. The available surface area for exchange is reduced, the diffusion distances are increased. In themselves, these changes are no acute threat to the survival of the entire individual. In combination with other defects, they are capable of sustaining prolonged states of flow arrest. Since the rheological properties of blood can be easily manipulated, sustained circulatory deficiencies can be avoided or treated by improving blood fluidity.

152 citations

Journal ArticleDOI
TL;DR: It is indicated that a pronounced circulatory deficit exists within the retinal vasculature of glaucomatous eyes, which may coexist with, but cannot be fully attributed to, an increase in plasma viscosity.

137 citations