The phenomenon of vein pulsation The venous retinal pulsation is occurring due to the blood pressure difference in the central retinal vein. The pressure difference occurs due to the condition of the systole and diastole pressure. The following are experimental studies carried out so far on physician experiment set-ups and existing theoretical models considered, wave surface with the Pulsations phenomena of collapsible vessels in the body deal. Few of these models are based on the anatomical and physiological conditions of the CRV, which is why most only the effect must be interpreted. Theoretical models Model according to DN Levine The theoretical model by Levine relates the phenomenon of pulsating Vein on the observed pulsations of the CRV. …show more content…
4.9) and represent the portion of the vein at the optic disc as it exits the eye (I), the intra-neural portion (II), the region through the nerve sheath where it crosses the subarachnoid space (III) and the extra-neural portion where the central retinal vein traverses outside the nerve to join the ophthalmic vein (IV), respectively. In the portion of the vein towards the rear of the eye (compartment I), the elastic wall is externally surrounded by vitreous humour at the IOP, while in the portion of the vein passing through the nerve sheath (compartment III), the elastic wall is externally surrounded by CSF at the ICP. Coupling between the IOP and ICP dictates the onset of the RVP. Other more sophisticated models for the elastic response of the vein are available, including for example its bending stiffness, but this study focuses on the simplest possible model. In compartment II the retinal vein is assumed to pass down the center of the optic nerve and so is unsheathed by nerve and connective tissue; therefore the vein wall can be assumed rigid. The vein wall in compartment IV is also assumed …show more content…
This threshold intraocular pressure depends on the phase shift, varying over a range of approximately 1.5mmHg for mean ICP of 0mmHg. There are two encouraging features emerging from this model: first, the threshold for the onset of large amplitude oscillations appears to be an approximately linear relationship between the IOP and the CSF pressure over a significant range, consistent with measurements in canines; second, predictions show only a modest dependency on the phase shift between the IOP and the ICP oscillations – for the model parameters chosen the maximal difference in the predicted onset IOP was 1.5mmHg across the range of phase shift. The model employs an idealized representation of the elastic vessel wall (neglecting bending stiffness), assumes simple sinusoidal waveforms for the ICP and IOP and neglects pulsatility in the inlet flow into the vein. The model also assumes that the diameter of the vein is constant along its length and ignores bifurcations. When the mean IOP is 18.5mmhg then the ICP is 0mmhg, IOP is increased to 18.5mmHg, the vessel wall in compartment
Mr. O 'Brien 's vial signs are consistent with the definition of orthostatic hypotension. His blood pressure continues to fall upon position changing and his heart rate is increasing in order to try to compensate for the fall in blood pressure. 2. Explain the steps of assessing orthostatic
Kevin Mc Kinney from the American academy of ophthalmology acknowledge that it exists different types of glaucoma and categorize them as follow: “1) Primary open angle glaucoma: this is the most common form of glaucoma. It occurs when the trabecular meshwork of the eye gradually becomes less efficient at draining fluid. 2) Normal tension glaucoma: that type of glaucoma arises even though the pressure in the eye is normal, but the optic nerve is damaged.3) Angle closure glaucoma: also called narrow angle glaucoma. It occurs when someone’s iris is very close to the drainage angle in their eye.
This comprises of attenuation of blood vessels, waxy disc pallor and a mottled appearance of the retinal pigment epithelium which is caused by the formation of bone spicule. Internal limiting membrane wrinkling, buried drusen of the optic nerve head, cystoid macula edema, cataracts (usually PSC) and vitreous pigmentation and syneresis may also be seen. Symptoms of this disease include night blindness, tunnel vision, photopsia, photophobia, difficulty adjusting from light to dark environments and vice versa, blurry vision, poor colour separation, loss of central vision (late stage) and blindness eventually. RP may occur as an isolated disease (non syndromic which is the typical form of disease) or in combination with systemic disease (syndromic). Usher syndrome is the most common form of syndromic RP.
Deep Venous Thrombosis There are both superficial and deep veins in the limbs or extremities (arms and legs). A blood clot in the deep veins is a concern because it can cause life-threatening complications. A deep vein thrombus is a blood clot or thrombus that develops in deep vein usually in leg; here they pass through the center of leg, surrounded by muscles, less commonly Deep Venous Thrombosis occurs in deep veins of arm or pelvis. A blood clot is a clump of blood that is in a gelatinous, solid state.
The fluid material used in this case is water. The cell zone conditions must now be converted from air to the liquid water. A boundary condition is created at the inlet surface as a velocity magnitude of 0.2m/s. The velocity is set to 0.2m/s, which represents the blood flow along the cylinder. Finally, the simulation can be performed using the run calculation tool.
The increased venous return results in end-diastolic volume increase, which generates stretching of ventricular muscle fibres causing an increase in stroke
Trabeculectomy Bleb Function after uneventful phacoemulsification Abstract Background: The aim of this study was to compare superior and temporal clear corneal incisions of uneventful phacoemulsification and in-the-bag intraocular lens implantation on intraocular pressure control and the bleb morphology in eyes that have undergone previous successful trabeculectomy. Methods: In this Prospective case-control study, a total of 100 eyes of 100 patients previously undergone trabeculectomy without antimetabolites, divided into two groups.
2) Arterial Doppler: Arterial Doppler on both lower limbs was done to all subjects in the study. How was it prepared: We asked participants to rest and stop using products that contain nicotine (cigarettes, chewing tobacco) for 30 minutes to 2 hours before the test. Nicotine causes blood vessels to constrict and may give false results.
Introduction This essay will reflect on my personal experience, skills, and knowledge gained from my studies and practice of undertaking blood pressure (Bp) whilst completing my professional placement. Bp may be defined as a force of blood against vessel walls in the body, consisting of systolic and diastolic pressure measured in millimeters of mercury. (Waugh and Grant, 2016) Systolic pressure occurs when the hearts left ventricle contracts and forces blood into the aorta causing a heightened atrial pressure, while diastolic pressure refers to complete cardiac diastole, this is when the aortic valve closes and pressure is at its lowest between beats, blood moves into smaller corresponding vessels and the heart rests.
Additionally, we observed a focal serous retinal detachment associated with hyperreflective dots in the interdigitation zone of the foveal region. The OCT-A choriocapillaris segmentation showed a high flow structure composed of filamentous linear vessels, forming anastomoses and loops, associated with a peripheral arcade surrounded by a dark halo. (Fig. 8) Case
Courtesy of Degertekin, Hesler, & Karaman (2011:[n.p.]). The mechanical type IVUS transducer is demonstrated in figure 2. This type of transducer makes use of rotating ultrasound sources. The ultrasound signal fills the entire vessel lumen while no signal interference presents.
The term pericardium is derived from the Greek prefix peri- (“around”) and kardia (“heart”), implying a structure that envelops or encloses the heart. Morphologically, the pericardium is a fluid-filled sac-like structure that surrounds the heart. Anatomic Structure The pericardium is a double-walled structure, made up of an outer fibrous layer and an inner serous layer. The fibrous layer is a single, connective tissue layer, made up of collagen (type I and type III mainly) and elastin fibers; it is elastic and yet non-distensible.
Balloon catheter based circulatory measurement system Introduction In hospitals, doctors use many devices to help them cure their patients from various health problems. These are called Medical Devices. Medical devices help doctors do many things, ranging from diagnostics, therapy, to life support. Medical devices that are used to diagnose a patient are very important as they can help the doctor to understand and thus cure the patient’s problem.
[29] in this case characterized the linear viscoelastic material properties of peripapillary sclera in both the rabbit and monkey eyes using a coupled spectral reduced relaxation function. The
Hypertension commonly known as high blood pressure is the phenomena when the blood with all its power and strength pushes through the walls of arteries as it pass through them. Arteries are responsible for carrying oxygenated blood to the body tissues from the heart. Blood pressure is linked with the speed of blood hitting through the artery walls. Blood vessels with smaller capacity also gets affected by the pressure of the blood. The swiftness blood pressure is lower when the walls of the arteries are more relaxed or opened than narrow or tight (1).