View clinical trials related to Low 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.
Color Doppler Imaging (CDI) has been providing information about ocular blood flow over the past decades. This non-invasive procedure based on ultrasound technique has identified increased resistance and decreased systolic blood velocities to exist in the ophthalmic arteries of glaucoma patients. However, existing data has provided very little information regarding the analysis of the Doppler waveform in itself and to whether variables such as early systolic acceleration or systolic/diastolic velocity ratios are of any significance in glaucoma disease. In other medical specialties using CDI technology, such as nephrology or cardiology for instance, this analysis has been part of the normal routine. This information has been used in screening patients for disturbed circulation such as arterial stenosis or providing information regarding prognosis of renal and hepatic transplants have been used for decades now. What is the normal characteristics of the waveform Doppler analysis? To answer this, the investigators will create a normative database using healthy controls. Are there signs of altered stiffness or compliance in the ophthalmic arteries of glaucoma patients? To answer this, the analysis of early acceleration acceleration and detection of an early peak systolic will be done on the Doppler curves of glaucoma patients and compared to the healthy normative database. Are there any difference between the two types of glaucoma [primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG)]? The investigators will compare the variables of the ophthalmic artery waveform in these two groups. Do any of these Doppler waveform variables have any clinical significance? To answer this, the investigators will search for the existence of any correlation between the waveform data and both functional (visual field testing) and structural (Confocal scanning laser ophthalmoscopy - CSLO) variables of the glaucoma groups.
Purpose To evaluate efficacy and safety of combigan(Brimonidine/Timolol) and 0.5% Timoptic (Timolol) ophthalmic solutions in normal tension glaucoma patients.
Retinal ischemia is thought to play an important role in the pathogenesis of glaucoma. Up until today, very little is known about the metabolic alterations in the retina of glaucoma patients, since only techniques for surrogate measurements of metabolism (like blood flow velocities and vessel diameter) were available. Oximetry has provided us with an important tool to study metabolism in glaucoma, and to correlate these findings with the available blood flow evaluation techniques. Preliminary results by the group of Prof Stefánsson (2011) with the dual wavelength oximeter pointed out that deeper glaucomatous visual field defects are associated with decreased arteriovenous differences in retinal oxygen saturation. These data suggest that a change in oxygen metabolism occurs in glaucomatous retina. This reduced oxygen metabolism may be related to tissue atrophy. However, this explanation is still hypothetical, since the relation between these oximetry results and structural changes in the optic nerve have not been studied yet. 1. What are the oximetry values in a normal population of within the same age group as the glaucoma population? To answer this question, a normative database of the investigators retinal oximetry device needs to be constructed for healthy controls. 2. Do glaucoma patients have different retinal oximetry values than these normal patients? Are there any differences in retinal oxygenation between these glaucoma groups? To answer these questions, oximetry measurements will be performed in patients with normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). 3. Is there an association between structural optic disc and retinal nerve fibre layer changes, using Heidelberg Retinal Tomography (HRT), with alterations in retinal vascular oxygen saturation in NTG and POAG patients? 4. Are blood flow measurements, using colour Doppler imaging (CDI), correlated with alteration in retinal vascular oxygen in NTG and POAG patients?