scholarly journals Intraocular Pressure, Blood Pressure, and Retinal Blood Flow Autoregulation: A Mathematical Model to Clarify Their Relationship and Clinical Relevance

2014 ◽  
Vol 55 (7) ◽  
pp. 4105 ◽  
Author(s):  
Giovanna Guidoboni ◽  
Alon Harris ◽  
Simone Cassani ◽  
Julia Arciero ◽  
Brent Siesky ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Blood Flow ◽  
Intraocular Pressure ◽  
Clinical Relevance ◽  
Retinal Blood Flow

Intraocular pressure and retinal blood flow in the normal and glaucomatous eye

1992 ◽  
Vol 55 ◽  
pp. 171
Author(s):  
Juan E. Grunwald
Keyword(s):  
Blood Flow ◽  
Intraocular Pressure ◽  
Retinal Blood Flow

Retinal Vascular Implications of Ocular Hypertension

2021 ◽  
Author(s):  
Fidan Jmor ◽  
John C. Chen
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Intraocular Pressure ◽  
Vascular Anatomy ◽  
Flow Regulation ◽  
Retinal Blood Flow ◽  
Vein Occlusion ◽  
Ocular Perfusion ◽  
The Relationship ◽  
Central Retinal Vein

In this chapter, we review the basics of retinal vascular anatomy and discuss the physiologic process of retinal blood flow regulation. We then aim to explore the relationship between intraocular pressure and retinal circulation, taking into account factors that affect retinal hemodynamics. Specifically, we discuss the concepts of ocular perfusion pressure, baro-damage to the endothelium and transmural pressure in relation to the intraocular pressure. Finally, we demonstrate the inter-relationships of these factors and concepts in the pathogenesis of some retinal vascular conditions; more particularly, through examples of two common clinical pathologies of diabetic retinopathy and central retinal vein occlusion.

scholarly journals Modelling of hydrogen diffusion in the retina

2020 ◽  
Vol 61 ◽  
pp. C119-C136
Author(s):  
Wafaa Mansoor ◽  
Graeme Hocking ◽  
Duncan Farrow
Keyword(s):  
Mathematical Model ◽  
Blood Flow ◽  
Oxygen Transport ◽  
Hydrogen Diffusion ◽  
Theoretical Models ◽  
Retinal Blood Flow ◽  
Inert Gas ◽  
Mathematical Methods ◽  
Physiol Heart Circ ◽  
Hydrogen Clearance

A simple mathematical model for diffusion of hydrogen within the retina has been developed. The model consists of three, well-mixed, one dimensional layers that exchange hydrogen via a diffusion process. A Fourier series method is applied to compute the hydrogen concentration. The effect of important parameters is examined and discussed. The results may contribute to an understanding of the hydrogen clearance technique to estimate blood flow. A two dimensional numerical method for the hydrogen diffusion is also presented. It is shown that the predominant features of the process are captured quite well by the simpler model. References V. A. Alder, D. Y. Yu, S. J. Cringle and E. N. Su. Experimental approaches to diabetic retinopathy. Asia-Pac. J. Ophthalmol. 4:20–25, 1992. J. C. Arciero, P. Causin and F. Malgoroli. Mathematical methods for modeling the microcirculation. AIMS Biophys. 4:362–399, 2017. doi:10.3934/biophy.2017.3.362 D. E. Farrow, G. C. Hocking, S. J. Cringle and D.-Y. Yu. Modeling Hydrogen clearance from the retina. ANZIAM J. 59:281–292, 2018. doi:10.1017/S1446181117000426 A. B. Friedland. A mathematical model of transmural transport of oxygen to the retina. Bull. Math. Biol. 40:823–837, 2018; doi:10.1007/BF02460609 D. Goldman. Theoretical models of microvascular oxygen transport to tissue. Microcirculation 15:795–811, 2008. doi:10.1080/10739680801938289 A. C. Hindmarsh. ODEPACK, A Systematized Collection of ODE Solvers. In Scientific Computing, R. S. Stepleman, et al., Eds., pp. 55-64. North-Holland, Amsterdam, 1983. S. S. Kety. The theory and applications of the exchange of inert gas at the lungs and tissues. Pharmacol. Rev. 3:1–41, 1951. http://pharmrev.aspetjournals.org/content/3/1/1 B. P. Leonard. A stable and accurate convective modelling procedure based on quadratic upstream interpolation. Comput. Methods Appl. Mech. Eng. 19:59–98, 1979. doi:10.1016/0045-7825(79) 90034-3 S. L. Mitchell. Coupling transport and chemistry: numerics, analysis and applications. PhD thesis, University of Bath, UK, 2003. https://researchportal.bath.ac.uk/en/studentTheses/coupling-transport-and-chemistry-numerics-analysis-and-applicatio G. A. Winchell. Mathematical model of inert gas washout from the retina: evaluation of hydrogen washout as a means of determining retinal blood flow in the cat. Master\textquoteright s Thesis, Northwestern University, Evanston, USA, 1983. https://search.library.northwestern.edu/permalink/f/5c25nc/01NWU_ALMA21563278530002441 D. Y. Yu, V. A. Alder and S. J. Cringle. Measurement of blood flow in rat eyes by hydrogen clearance. Am. J. Physiol. (Heart Circ. Physiol.) 261:H960–H968, 1991. doi:10.1152/ajpheart.1991.261.3.H960 D. Y. Yu, S. J. Cringle, V. A. Alder, E. N. Su, and P. K. Yu, Intraretinal oxygen distribution and choroidal regulation in the avascular retina of guinea pigs. Am. J. Physiol. (Heart Circ. Physiol.) 270:H965-H973, 1996. doi:10.1152/ajpheart.1996.270.3.H965 S. Cringle, D.-Y. Yu, V. Alder, E.-N. Su, and P. Yu. Choroidal regulation of oxygen supply to the guinea pig retina. In A. G. Hudetz, and D. F. Bruley (Eds.), Oxygen Transport to Tissue XX, pp. 385–389. Springer, 1998. doi:10.1007/978-1-4615-4863-8

scholarly journals Comparison of Intraocular Pressure, Blood Pressure, Ocular Perfusion Pressure and Blood Flow Fluctuations During Dorzolamide Versus Timolol Add-On Therapy in Prostaglandin Analogue Treated Glaucoma Subjects

2012 ◽  
Vol 5 (3) ◽  
pp. 325-338 ◽  
Author(s):  
Ingrida Januleviciene ◽  
Lina Siaudvytyte ◽  
Vaida Diliene ◽  
Ruta Barsauskaite ◽  
Daiva Paulaviciute-Baikstiene ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Intraocular Pressure ◽  
Perfusion Pressure ◽  
Prostaglandin Analogue ◽  
Ocular Perfusion Pressure ◽  
Ocular Perfusion ◽  
Flow Fluctuations

scholarly journals Blood pressure and blood flow variation during postural change from sitting to standing: model development and validation

2005 ◽  
Vol 99 (4) ◽  
pp. 1523-1537 ◽  
Author(s):  
Mette S. Olufsen ◽  
Johnny T. Ottesen ◽  
Hien T. Tran ◽  
Laura M. Ellwein ◽  
Lewis A. Lipsitz ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Blood Flow ◽  
Young Subject ◽  
Venous Blood ◽  
Cardiovascular Responses ◽  
Physiological Data ◽  
Postural Change ◽  
Metabolic Demand ◽  
Arterial Blood

Short-term cardiovascular responses to postural change from sitting to standing involve complex interactions between the autonomic nervous system, which regulates blood pressure, and cerebral autoregulation, which maintains cerebral perfusion. We present a mathematical model that can predict dynamic changes in beat-to-beat arterial blood pressure and middle cerebral artery blood flow velocity during postural change from sitting to standing. Our cardiovascular model utilizes 11 compartments to describe blood pressure, blood flow, compliance, and resistance in the heart and systemic circulation. To include dynamics due to the pulsatile nature of blood pressure and blood flow, resistances in the large systemic arteries are modeled using nonlinear functions of pressure. A physiologically based submodel is used to describe effects of gravity on venous blood pooling during postural change. Two types of control mechanisms are included: 1) autonomic regulation mediated by sympathetic and parasympathetic responses, which affect heart rate, cardiac contractility, resistance, and compliance, and 2) autoregulation mediated by responses to local changes in myogenic tone, metabolic demand, and CO2 concentration, which affect cerebrovascular resistance. Finally, we formulate an inverse least-squares problem to estimate parameters and demonstrate that our mathematical model is in agreement with physiological data from a young subject during postural change from sitting to standing.

Comparison of Visual Function and Ocular Hemodynamics between Pre- and Post-Menopausal Women

2008 ◽  
Vol 18 (2) ◽  
pp. 320-323 ◽  
Author(s):  
B.A. Siesky ◽  
A. Harris ◽  
C. Patel ◽  
C.L. Klaas ◽  
M. Harris ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Intraocular Pressure ◽  
Contrast Sensitivity ◽  
Premenopausal Women ◽  
Menopausal Women ◽  
Post Menopausal ◽  
The Right ◽  
Ocular Hemodynamics

Purpose The incidence of eye disease increases with age and can often be linked to worsening cardiovascular function and increasing intraocular pressure. Estrogen is known to have vasodilatory effects in the systemic circulation. Decreased estrogen levels during menopause may therefore complicate or contribute to ocular pathologies as estrogen receptors are found in both retinal and choroidal tissue. The purpose of this investigation was to determine the effects of menopause on visual function and cardiovascular and ocular hemodynamics. Methods Twelve premenopausal and 24 postmenopausal women were evaluated at the Indiana University School of Medicine during a single study visit. Vision screening and ocular blood flow evaluations were performed, including blood pressure, heart rate, visual acuity, contrast sensitivity, intraocular pressure, and retinal capillary and retrobulbar blood flow imaging. Vision and ocular hemodynamics were compared using unpaired Student t-tests with pp<0.05 regarded as statistically significant. Results The premenopausal group had significantly lower heart rate (-16.1 b/m, p=0.0001) and systolic blood pressure (-17.7 mmHg, p=0.003) than postmenopausal subjects. Contrast sensitivity was significantly higher (measured in log units) in premenopausal women in both the right (0.25, p=0.039; 0.16, p=0.039) and left (0.45, p=0.001; 0.27, p=0.032) eyes at 9 and 18 cycles per degree, respectively. Premenopausal women also had significantly lower intraocular pressure in both the right (-2.19 mmHg, p=0.024) and left (-1.74 mmHg, p=0.035) eyes. Total ocular perfusion was not significantly different between groups. Conclusions This pilot work suggests that postmenopausal women have lower contrast sensitivity detection and elevated intraocular pressures compared to premenopausal women. Premenopausal women have lower cardiovascular risk factors, while total ocular circulation was similar to post-menopausal women.

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