Active clinical trials for "Low Tension Glaucoma"

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 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.

The objective of this study is to determine whether systemic blood pressure in the body is related to the development and progression of normal tension glaucoma in the eye. The study aims to clarify whether subjects with episodes of hypotension (low blood pressure) at night are at increased risk for sight loss and the development of normal tension glaucoma.

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.

To obtain demographic and baseline ophthalmic parameters (such as Intraocular Pressure profiles, disc morphological characteristics, central corneal thickness, peripapillary retinal nerve fibre layer thickness and its serial changes, visual field changes, severity of any medical associations-e.g. hypertension, migraine, strokes, silent cerebral infarcts) with non-invasive measurements, in Chinese Patients with Normal Tension Glaucoma

It is suggested the pathogenesis of normal-tension glaucoma (NTG) involves vascular dysregulation. In the past studies, it is well documented that many physical problems related to vascular dysregulation, such as angina pectoris (Friedman M et al 1974; Russek HI et al 1976), migraine (Diener HC et al 1994), primary Raynaud's disease (Wagner HH et al 1993) and stroke (Gainotti G, et al, 2001; Hayee Ma et al 2001), are associated with a high risk of depressive illness. So, NTG, being a disease involving vascular dysregulation, is postulated to be associated with psychopathology. Glaucoma increases after 40 year-old and the number of people over this age in Hong Kong is rapidly growing. However, we have no knowledge about the link between psychopathology and NTG in Hong Kong. The present study is sought to overcome the limitation in previous research and the goals of present study are: To identify the prevalence of psychopathology of normal-tension glaucoma Hong Kong Chinese Out-patients attending a university-affiliated glaucoma clinic. To determine whether there are any differences among NTG patients, patients with glaucoma other than NTG and control in terms of psychopathology and quality of life. Designs: Case-control study to compare among patients with normal-tension glaucoma (NTG), patients with glaucoma other than normal-tension glaucoma (OTNTG) and control in terms of psychopathology and quality of life

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.

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

since glaucoma is considered an optic neuropathy, new treatments for glaucoma are being continuously investigated, including neuroprotection. Previous studies implied that phenytoin, a potent anti-convulsive drug, has a neuroprotective role, and Na+ channels blockage was suggested as a possible mechanism. This study predicts that glaucoma patients taking Phenytoin will have a less advanced glaucoma as compared to patients not taking the drug. Glaucoma severity will be determined by visual acuity, visual fields, optic disc cupping and nerve fiber layer thickness

Metabolomics consists in the study of metabolites in body fluids or tissues. It investigates the consequences of the activity of genes and proteins. One of its advantages is that it is able to do a simultaneous measurement of metabolic changes in living organisms as a response to a disturbance (disease, diet, environment, others) and because a metabolic profile is summative of all the biochemical processes occurring in the body at a given time, it makes no presumption about the relative importance of these processes. Ultimately it is a fingerprint of the organism's health status, at a given time. Metabolomic analysis of serum, plasma and urine has revealed panels of metabolites that distinguish patients with cardiovascular disease, breast cancer, Parkinson disease, Alzheimer's disease and diabetes from control patients. Regarding ocular diseases only few studies have been published, related to diabetic retinopathy, retinal detachment, age-related macular degeneration, uveitis and glaucoma. Glaucoma is one of the leading causes of blindness in the world, according to the World Health Organization, and there are still no biomarkers that can provide an early diagnosis. Nowadays, glaucoma classification relies substantially in the measurement of intraocular pressure (IOP), which can be rather artificial and also unreliable since IOP values can fluctuate during the day. Moreover, patients with normal IOP values can also develop glaucomatous neuropathy (normal-tension glaucoma, NTG) and progress even when IOP is decreased. Several studies have shown that NTG patients suffer from a systemic vascular dysregulation, with higher rates of systemic hypotension, Raynaud phenomenon and migraine. Hence, other mechanisms than an increased IOP are of importance in the development and progression of glaucoma. Only one metabolome-wide study has been made in glaucoma (Burgess, I.; 2015). In a sample of 72 american patients with primary open angle glaucoma (POAG), the authors found significant differences in comparison to controls. The hypothesis for this study is that glaucoma patients will differ from controls, and POAG patients will differ from NTG patients. The investigators will look into metabolomics as a way to create a method to diagnose and stratify patients, as an add-on or alternative to the currently available diagnostic tools like IOP, functional and structural measurement.