View clinical trials related to Normal Tension Glaucoma.
Filter by:Clinical features, optical coherence tomography findings and surgical outcome in eyes with macular retinoschisis and detachment with normal tension glaucoma but without optic disc pit or high myopia were evaluated.
Glaucoma is a leading cause of blindness worldwide, whose treatment - intraocular pressure lowering - is only partially effective in preventing disease progression. Accordingly, other variables, such as ocular blood flow-related factors, have been implicated in disease pathogenesis. However, most findings involving vascular variables come from partial, small-scale studies. Furthermore, recent technological advances have identified a number of ocular blood flow variables that have yet to be tested in large scale trials. Therefore, a study that specifically aims at uncovering the role of vascular aspects in glaucoma is needed. For this purpose, a cross-sectional, observational case-control study will be conducted in the University Hospitals Leuven. This will be the largest-yet study on the subject, involving more than 750 patients. This will allow the creation of a specific cohort of patients where the vascular aspects are thought to be particularly important (low-tension glaucoma). It will use the largest combination yet of vascular-related measuring techniques (dynamic contour tonometry, optic coherent tomography, colour Doppler imaging and retinal oximetry)
Ocular blood flow has been consistently demonstrated to be altered in glaucoma patients when compared to otherwise healthy individuals. Numerous Doppler studies have shown a decrease in flow velocities in the retrobulbar arteries in what appears to be related to the degree of the glaucomatous disease. The anatomic pathway of the several arteries into the eye is intricately complicate, with at least one of them (the central retina artery) penetrating the optic nerve before entering the eye and supplying the innermost structures of the globe. As the optic nerve is surrounded by a layer of cerebrospinal fluid (CSF) which is in continuity with the rest of the central nervous system, this central retinal artery has also to cross this CSF containing compartment. Because of the intrinsic pressure this CSF - corresponding to the intracranial pressure at the orbital level - the possibility exists that this pressure around the optic disc could affect the blood flow of the arteries that go through it. The investigators will try to detect if a correlation exists between the optic nerve sheath diameter and the blood flow in the retrobulbar vessels of glaucoma patients.
A spontaneous venous pulsation over the optic disc is an ophthalmological sign that can potentially be found in up to 98% of healthy individuals. In fact, the lack of this spontaneous retinal venous pulse has been consistently implicated as an indicator of a more advanced form of certain ocular diseases, specifically open-angle glaucoma. However, the mechanisms behind these change in the retinal venous system are not clear. Some evidence suggests that extraocular features such as intracranial pressure (ICP) may play a role in regulating the intraocular venous outflow. The reasons for this hypothetical downstream resistance to venous outflow are not fully understood, with advances in this field being limited by our technological-imposed difficulties in assessing the structures behind the globe. However, it has been established that the volume of cerebrospinal fluid surrounding the optic nerve correlates with the ICP at the orbital level. Recent studies have suggested that non-invasive ultrasound-based recordings have correlated this surrogate for orbital ICP with the intraocular pressure (IOP) in glaucoma patients with an otherwise normal IOP range (normal tension glaucoma - NTG). The investigators will therefore conduct a test to determine if this cerebrospinal volume surrounding the optic nerve correlates with the frequency of observation of an otherwise signal of venous dysfunction (i.e. the lack of a visible pulse in the retinal central vein) Additionally, the investigators will assess if this correlation is different between healthy individuals, hypertensive primary-open angle glaucoma or NTG patients.
Retinal ischemia is thought to play an important role in the pathogenesis of glaucoma. Recent findings have confirmed that there is a direct correlation between the levels of venous oxygen saturation and the degree of the glaucomatous disease, presumably due to a decrease in retinal cell metabolism. However, glaucoma patients have been suggested to have a different pattern in retinal venous circulation. For instance, the observation of a visible pulsating central retinal vein is a phenomenon that can be seen in up to 98% of the healthy individuals but is identifiable in less than 50% of glaucoma patients. While the nature of these venous changes are not year clear, the lack of a visible pulsating flow could suggest an increased intraluminal venous pressure due to some obstruction from both ocular or extraocular structures. This undetermined increase in venous pulse pressure could then significantly decrease perfusion pressures and therefore further decrease oxygen supply to the retinal tissues. The investigators will therefore try to determine if there is a significant difference between the oxygen saturation of the retinal vessels in both glaucoma patients with and without a visible pulsating central vein
Interplay between the increasing IOP and decreasing blood pressure (BP) during the 24-hour period, especially in the nocturnal period, may lead to insufficient perfusion pressure of the optic nerve and contribute to the glaucomatous damage in adjunct to the antero-posterior vectorial mechanical impact on the lamina cribrosa, the translaminar pressure. Patients with progressive VF loss showed greater nocturnal BP dips than patients with stable VF. Reduced mean intraocular perfusion pressure (IOPP) was significantly associated with the extent of glaucomatous damage. How the nycthemeral IOP fluctuation influences glaucoma progression has not been studied in a prospective manner and remains to be elucidated. The purpose of this study is to assess the relationship between the 24-hour IOP fluctuation pattern and the 24-hour BP pattern in patients with primary open angle glaucoma (POAG). IOP fluctuations will be monitored with SENSIMED Triggerfish®, a portable investigational device using a contact lens sensor that monitors the IOP fluctuation continuously over 24-hours.
The purpose of the study is to prove if there is any difference in the nerve fiber layer between patients with normal- and high-tension-glaucoma with similar structural optic nerve head parameters.
Purpose To evaluate efficacy and safety of combigan(Brimonidine/Timolol) and 0.5% Timoptic (Timolol) ophthalmic solutions in normal tension glaucoma patients.
The primary purpose of this study is to determine whether topical ophthalmic anesthetics lower the intraocular pressure in the eye.
Evidence has accumulated that systemic and ocular mechanisms, responsible for regulating blood flow in the area of the optic disc, such as reduced ocular perfusion pressure, abnormal autoregulation and vascular dysregulation may be involved in the pathogenesis of normal tension glaucoma (NTG). Defective cardiovascular neuroregulation has been advocated as a possible one of the main systemic contributing factors in the etiology of NTG. Based on the results of previous studies, the hypothesis has been posed that patients with NTG have an impaired diurnal heart rate variability (HRV) or high activity of the sympathetic component of autonomic nervous system (ANS) and endothelial dysfunction. Impaired balance of ANS, resulting in increased demand for oxygen in the tissues and subsequent low threshold of hypoxia in all organs (including the eye) can be an important link in the pathogenetic pathway of NTG, making the optic nerve more sensitive to small and short-term changes in perfusion pressure and prone to damage even under a statistically "normal" intraocular pressure (IOP). The aim of this study is to evaluate the activity and characteristics of the following systems: the central ANS (through a 24-hour analysis of heart rate variability and blood pressure), peripheral vascular system (through the analysis of the post-occlusive hyperemia reaction within the distal part of left upper limb) and the local retrobulbar circulation as measured by color Doppler imaging (CDI) in patients with NTG and healthy volunteers. The correlations between all above systems, as well as between them and the structural and functional parameters of the optic nerve, and the retina in both groups will be also analyzed.