Active clinical trials for "Glaucoma, Open-Angle"

This study is designed to investigate whether the pupil response to slowly flashing colored lights is significantly altered in patients with glaucoma, as compared to a control group of subjects without glaucoma.

This study aims at validating in real-life clinical practice and using the self-reported Glaucoma Symptom Scale (GSS) questionnaire, the impact of a switch to preservative-free dorzolamide/timolol fixed combination (DTFC) in patients using preserved topical therapy for glaucoma.

The purpose of this study is to determine which medical, demographic, and health belief factors are associated with glaucoma therapy compliance.

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. 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. 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). 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? Are blood flow measurements, using colour Doppler imaging (CDI), correlated with alteration in retinal vascular oxygen in NTG and POAG patients?

To evaluate whether add-on to prostaglandin therapy with twice a day (bid) dorzolamide is statistically superior to twice a day (bid) timolol with regard to increasing ocular blood flow

This descriptive, non-interventional study will collect information on the presence of risk factors in newly diagnosed ocular hypertension and open-angle glaucoma patients in Canada.

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.

Perimetry is a well-established method that is used to measure the visual field functions of humans. Commercially available products, such as the OCTOPUS 900 (Haag-Streit AG, Koeniz, Switzerland), are commonly used for assessing the visual field. Such devices are of critical value for patients suffering of glaucoma and neuro-ophthalmic conditions. The operating principle is to sequentially present light stimuli of different intensity at different locations within the visual field in an automatic way. Algorithms that select what locations and intensities to present over time are called strategies. These have the goal to provide both a fast and accurate estimation of the visual field function. Recently, new strategies were developed that are faster and equally accurate as the strategies used today. The technological advancement of these new methods lies primarily in the ability to estimate location sensitivities without observing them directly but by leveraging previously queried locations. For this the investigators plan to implement the next generation of perimetry strategies into an OCTOPUS 900 and to test it in healthy subjects and glaucoma patients.

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.

Open angle glaucoma (OAG) is considered a common cause of irreversible vision loss worldwide. It is an optic neuropathy associated with progressive loss and degeneration of the retinal ganglion cell layer (RGC) and its axons (retinal nerve fiber layer; RNFL), which lead to neuroretinal rim excavation and corresponding visual field defects.