View clinical trials related to Low Tension Glaucoma.
Filter by:The purpose of this study is the investigation of biomechanical properties of the cornea using computer-aided data analysis. Currently, it is known that keratoconus and glaucoma are ocular disease that are associated with biomechanical alterations of the cornea. Corneal ectasia, especially keratoconus, is a corneal disease that leads to an irreversible loss of visual acuity while the cornea becomes steeper, thinner and irregular. For these patients, surgical intervention (e.g. corneal cross-linking) is performed, in case of disease progression. In glaucoma, the information about corneal alterations serves in two ways, first, correct measurement of intra ocular pressure (IOP); second, early diagnosis of suspects before visual field defects are detectable. Especially, the Corvis ST is an air-puff tonometer that measures intraocular pressure, corneal thickness (CCT) as well as dynamic corneal response (DCR) parameters. Most of the DCR parameters are affected by IOP and CCT: Therefore, algorithm are needed to determine parameters without impact of IOP and CCT that are describe the biomechanical properties of the cornea.
In addition to intraocular pressure blood perfusion pressure in the optic nerve is an important factor determing the cause of glaucoma. Increasing evidence suggests that in glaucoma patients retinal blood may be decreased.
Glaucoma is the second leading cause of blindness worldwide. Literature shows increasing evidence that dysfunction of ocular microcirculation in the optic nerve influences the progression of glaucoma. It has been shown that flicker light-induced vasodilatation of retinal veins is diminished in patients with glaucoma. Also previous studies indicate that the blood flow autoregulation is impaired in patients with glaucoma. Therefor the ocular perfusion pressure can not be maintained stable during changes of the systemic arterial blood pressure. Laser speckle flowgraphy (LSFG) represents a non-invasive method to quantify ocular perfusion also at the ONH. LSFG enables noninvasive quantification of microcirculation of the optic disc in Japanese glaucoma patients. Study Objectives: To assess the changes in LSFG parameters in patients with normal tension glaucoma, compared to healthy subjects during flicker light stimulation and isometric exercises.
Glaucoma is characterized by a progressive loss of retinal ganglion cells (RGCs) leading to optic nerve head (ONH) damage and associated visual field defects. The main risk factor for glaucoma is elevated intraocular pressure (IOP). Reducing IOP slows down the progression of the disease as several large multicenter trials have shown. Some patients, however, still progress despite adequately controlled IOP. As such, there is considerable interest in approaches that rescue RGCs independent of IOP, a strategy called neuroprotection. Although this field was actively discovered in the last 20 years in the brain and the eye, no non-IOP related treatment is clinically available to date. Various approaches are currently studied in some detail. One interesting strategy focuses on the neurovascular unit. The blood flow of the human retina is controlled by complex mechanisms that include myogenic, metabolic and hormonal factors. The high consumption of oxygen in the human retina is crucial for normal functioning of the organ. As in the brain, blood flow in the retina is also controlled by neurovascular coupling. This means that the retina increases its blood flow to regions in which neurons are activated. This is done in an effort to provide more oxygen and glucose to the active neurons. In the recent years evidence has accumulated that astrocytes play a key role in mediating this vasodilator signal. In the brain, abnormalities in neurovascular coupling have been observed in diseases like stroke, hypertension, spinal-cord injury and Alzheimer's disease. This break-down of neurovascular coupling is considered to play a key role in neuronal death in these diseases. In the retina, abnormalities in neurovascular coupling have been observed in diseases as diabetes and glaucoma. Most of the data obtained in the human retina stem from a system that measures retinal vasodilatation during stimulation with flickering light. The investigators have previously shown that flicker stimulation of the retina is, however, also associated with a pronounced increase in retinal blood velocities. In this study the investigators employed laser Doppler velocimetry (LDV) for the measurement of retinal blood velocities, but this technique is not clinically applicable because it requires excellent fixation of the subject under study. In the present study, the investigators propose to use an alternative system for neurovascular coupling that they have developed recently. In this approach, the investigators use bi-directional Fourier-domain optical coherence tomography for the assessment of retinal blood flow. Optical coherence tomography (OCT) is a non-invasive optical imaging modality enabling cross-sectional tomographic in vivo visualization of internal microstructure in biological systems. In ophthalmology, OCT has become a standard tool in visualizing the retina and nowadays is considered also as a standard tool in the diagnosis of retinal disease. In the recent years, conventional time domain OCT was replaced by Fourier domain OCT providing significantly improved signal quality. This bidirectional system overcomes the limitations of previously realized techniques, which include doubtful validity and limited reproducibility. In addition, pattern ERG, multifocal ERG and oscillatory potentials will be measured to allow for concomitant assessment of neural function. The investigators seek to measure neurovascular coupling in the human retina in patients with early primary open angle glaucoma (POAG), normal tension glaucoma, ocular hypertension and a healthy control group. In order to obtain information on neurovascular coupling, both neuronal function as well as retinal blood flow need to be measured. In the present study, the investigators will employ pattern ERG, multifocal ERG as well as oscillatory potentials to assess the function of the inner retina. Retinal blood flow through major retinal arterial and venous branch vessels will be measured before, during and after flicker stimulation with the dual-beam bidirectional Fourier Domain Doppler OCT coupled to the commercially available Dynamic Vessel Analyzer (DVA) produced by IMEDOS, Jena, Germany, which provides adequate resolution to study the retinal circulation.
The purpose of this study is to evaluate the effect of Ginkgo biloba extract (GBE) on the number of blood vessels in the back of the eye as well as the amount of blood flow at the nailfold(where the fingernail meets the skin) of the 4th finger in the hand.This finger, along with the 5th finger, has the most transparent skin, which makes imaging a little easier. GBE is an over-the-counter pill, made from a natural powder taken from the Gingko (Maidenhair) tree, that is widely used. A technique called Optical Coherence Tomography Angiography (OCTA),will be used to measure the small blood vessels at the back of the eye, the macula (the area of sharpest vision), and the optic disc (the point at which the nerve fibers from the retina enter to form the optic nerve, which transmits visual impulses to the brain).
The study includes Caucasian patients with diagnosis of normal tension glaucoma and age- and sex-matched healthy individuals. Measurements of optic nerve head blood flow will be performed with laser speckle flowgraphy (LSFG). Also, the intraocular pressure (IOP), systolic and diastolic blood pressure, heart rate (HR), mean arterial pressure (MAP) as well as ocular perfusion pressure (OPP) will be evaluated. After baseline measurements individuals will be asked to ingest 800 ml of water in less than five minutes. Measurements will be repeated after 15, 30 and 45 minutes.
Purpose: To analyze the relationship between normal-tension glaucoma (NTG) and serum bilirubin levels. Materials and Methods: This research included 38 patients with NTG and 38 healthy controls with similar age and sex distribution, for a total of 76 subjects. Serum samples were taken from all of the subjects, direct serum bilirubin, indirect serum bilirubin and the total serum bilirubin were measured.
This study evaluates the possible acute changes in peripapillary blood flow after instillation of antiglaucoma medications in patients with primary open angle glaucoma (POAG), normal tension glaucoma (NTG), or ocular hypertension (OHTN) using Optical Coherence Tomography (OCT) angiography.
Glaucoma is the second leading cause of blindness worldwide. Literature shows increasing evidence that dysfunction of ocular microcirculation in the optic nerve influences the progression of glaucoma. Laser speckle flowgraphy (LSFG) represents a non-invasive method to quantify ocular perfusion also at the ONH. LSFG enables noninvasive quantification of microcirculation of the optic disc in Japanese glaucoma patients
The purpose of this study was to determine the incremental intraocular pressure (IOP) lowering that is achieved when Simbrinza is used adjunctively to Travatan in patients with normal tension glaucoma that may benefit from further IOP lowering.