View clinical trials related to Retina.
Filter by:Alzheimer disease is hard, long and expensive to diagnose. In order to help the clinician, a new biomarker in Alzheimer disease seems to be very useful. The retina, as a window of the brain, could offer a new way to diagnose this common disease. Indeed, a retinal atrophy could especially appear in Alzheimer disease. Besides, many aspects about retinal alteration, visual function and their link with the disease deserve to be more explored. So as to fill these gaps, a new study about retinal specificity in Alzheimer disease appears to be relevant.
Improvement of retinal medical imaging opens new perspectives for exploring the retinal structures. Optical coherence spectral domain (SD-OCT), which has been widely used in the last ten years, is certainly the most advanced device. In the analysis of patients without retinal disease using SD-OCT, granulations in the interdigitation area were observed. These granulations have never been described with this device. They could correspond either to the degradation products of the external segments of the photoreceptors or to melanosomes. A descriptive study of these granulations at different examination times and in different lighting situations would allow us to obtain essential information for a better understanding of this area. Based on the results, larger studies could explore this area more finely in retinal pathologies involving dysfunctions of photoreceptors or of the pigmentary epithelium.
This protocol is an extension of protocol 0002, Proof of Concept and Dose Ranging Study of carbidopa-levodopa in Neovascular AMD. that is a 3 month study of escalating doses of carbidopa-levodopa in neovascular AMD. This trial is a 9 month extension for patients who successfully complete protocol 0002 and wish to continue carbidopa-levodopa therapy. It will use the two higher dose regimens of protocol 0002. these will be assigned according to how well the higher dose was tolerated in protocol 0002.
Retinal emboli is a common phenomenon in cardiac catheterization. In this study the investigators evaluate the incidence of retinal emboli post diagnostic and therapeutic cardiac catheterization over 300 patients. The incidence was 6.3% and had no clinical sequel on visual acuity and visual field.
Impaired retinal blood flow has been implicated in the pathogenesis of diabetic retinopathy. Patel et al. (1992) showed that retinal blood flow increases with the level of diabetic retinopathy. Grunwald et al. (1996) reported that patients with insulin dependent diabetes mellitus (IDDM) of relatively short duration have increased retinal blood flow, even before the onset of diabetic retinopathy. On the other hand the data of Bursell et al. (1996) indicate that IDDM patients have reduced retinal blood flow, when they have normal blood glucose levels, but this study may have considerable methodological limitations. Acute elevations of blood glucose levels, however, result in an increase in retinal blood flow (Grunwald et al. 1987, Bursell et al. 1996). Based on previous experimental data the investigators hypothesize that ocular blood flow is increased in early diabetes and reduced at later stages of the disease. Previous studies have demonstrated that metabolic conditions such as hyperglycemia influence outcome parameters and thereby might have confounded results regarding ocular blood flow in diabetic retinopathy. The investigators will therefore study patients with IDDM during euglycemic conditions.
A number of common eye diseases such as retinal artery and vein occlusion, diabetic retinopathy, age-related macular degeneration, glaucoma and anterior ischemic optic neuropathy are associated with ocular perfusion abnormalities. Although this is well recognized there is not much possibility to improve blood flow to the posterior pole of the eye in these diseases. Since many years, moxaverine is used in the therapy of perfusion abnormalities in the brain, the heart and the extremities. This is based on a direct vasodilator effect of the drug, but also on the rheological properties of red blood cells. Whether moxaverine affects blood flow in the eye is unknown. The present study aims to investigate whether moxaverine may improves blood flow in the eye after systemic administration.
Glaucoma is one of the most common causes of blindness in the industrialized nations. For a long time glaucoma has been defined as a disease in which high intraocular pressure (IOP) leads to irreversible optic disc damage and subsequent visual field loss. However, recent investigations show that IOP is not the only factor that is involved in the glaucomatous process leading to retinal ganglion cell death. The role of vascular factors in the pathogenesis of glaucoma has recently received much attention based on animal experiments and epidemiological studies. The main focus of glaucoma is still directed towards a decrease in IOP. There is, however, also considerable interest whether antiglaucoma drugs influence ocular perfusion. Although measurement of ocular blood flow is still difficult, a number of innovative techniques have been realized which cover different aspects of ocular perfusion. In the present study Xalacom® (latanoprost/timolol) and the fixed combination of Combigan® (brimonidine/timolol) will be compared with respect to their IOP lowering efficacy as well as their ocular hemodynamic effects.
Idiopathic Macular Telangiectasia is characterized by incompetent and dilated retinal capillaries in the foveolar region of unknown cause for retinal telangiectasia. In Idiopathic Macular Telangiectasia, proliferative changes occur in the deep retinal capillary network, leading to intraretinal neovascularization that, unlike in age-related macular degeneration, seems to be retinal rather than choroidal in origin. Before the hemorrhagic and fibrotic state, these vessels may lead to exudation and decrease in the visual acuity. Long-term visual prognosis in patients with this complication may be poor and treatment with laser photocoagulation is unproven. Although newly reported treatment, by photodynamic therapy for neovascular membrane associated with Idiopathic Macular Telangiectasia, may show vision and angiographic stability in a few cases, the improvement may be transient. VEGF has been implicated as the major angiogenic stimulus responsible for neovascularization in AMD, ensuing specific anti-VEGF treatment in these cases. The purpose of the study is to evaluate intravitreal injection of bevacizumab (1.25mg/0.05ml) in the treatment of Idiopathic Macular Telangiectasia.
Habitual smoking is associated with an increased risk of coronary artery disease, cerebral and peripheral vascular disease, including ocular diseases like age-related macular degeneration or diabetic retinopathy. Data of a recent study performed in the investigators lab revealed abnormal choroidal blood flow regulation in chronic smokers as compared to age-matched non-smoking subjects during isometric exercise. However, no information is yet available about the regulation of retinal vascular tone in habitual smokers. Thus, in the current study, the investigators set out to investigate whether the regulation of retinal vessels diameters is affected in habitual smokers. It has been shown in several reports that stimulation with diffuse luminance flicker, increases retinal arterial and venous diameters, indicating for the ability of the retina to adapt to changing metabolic demands. In the current study we use this effect as a tool to investigate whether the flicker induced vasodilatation is affected in habitual smokers. This would indicate for an impaired vascular regulation process in smokers.
Oxidative stress, which refers to cellular damage caused by reactive oxygen intermediates, has been implicated in many disease processes, especially age-related disorders. Many trials investigating use of antioxidants in protecting different tissues against oxidative stress have been conducted, but the results are ambiguous. Inflammation is generally associated with enhanced oxidative stress and widespread endothelial dysfunction. In the present study, the infusion of LPS, which is a cell wall component of Gram-negative bacteria and a major mediator in the pathogenesis of septic shock, will be used as a standardized experimental model of systemic inflammatory response in humans. The assessment of outcome parameters will include measurements of ocular blood flow, forearm blood flow and plasma concentration of cytokines. Measurements of ocular hemodynamics provide an unique chance to investigate local blood flow in humans non-invasively. Moreover, the retina is especially susceptible to oxidative stress because of its high consumption of oxygen, its high polyunsaturated fatty acid content, and its exposure to visible light. Evidence from literature clearly supports a role for oxidative stress in pathophysiology of several ocular diseases including diabetic retinopathy and age-related macular degeneration. To investigate the retinal vascular reactivity we will use systemic hyperoxia as a stimulus. The measurement of forearm blood flow will be use to assess endothelial function. The main study objective is to investigate the effect of oral vitamins and minerals supplementation on impaired retinal vascular reactivity after LPS administration.