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An adequate oxygenation and retinal perfusion is essential for the function of the inner retina. There is a wide range of autoregulation mechanisms to ensure a sufficient ocular blood and oxygen supply during changes in systemic blood pressure or intraocular pressure (IOP). Nonetheless, various retinopathies such as diabetic retinopathy, which is the leading cause of blindness in people aged 20-65 in the western world, are highly associated with hypoxia (Pemp and Schmetterer 2008). Hence, measurements of oxygen levels in retinal vessels are needed to further our understanding of these ischemic diseases. It is a well known fact and a commonly employed method to measure oxygen saturation of blood through light transmission (Kramer 1934). However, this approach is not feasible in the human eye. Therefore, reflection must be used, meaning the amount of incident light must be estimated based on the amount of light reflected (for a review see Harris 2003). This is a difficult task and investigators in this field have encountered several problems, including optical complexities, nonlinear sensors and eye movement (Beach et al 1999; Delori 1988). Nonetheless considerable progress has been made over the past decades and the development of an reliable oximeter reported (Hardarson et al 2006).
In the present study this technique will be applied in healthy subjects as well as in patients with COPD during room-air conditions. The procedure takes approximately 15 minutes in each subject and will be performed in only one eye.
Observational Model: Cohort, Time Perspective: Prospective
Department of Clinical Pharmacology, Medical University of Vienna
Not yet recruiting
Medical University of Vienna
Published on BioPortfolio: 2014-08-27T03:18:33-0400
Central retinal artery occlusions (CRAO) are the equivalent of an ischemic stroke (IS) at the retinal level. They share the same risk factors and common pathology. Their incidence is lower...
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Sudden ISCHEMIA in the RETINA due to blocked blood flow through the CENTRAL RETINAL ARTERY or its branches leading to sudden complete or partial loss of vision, respectively, in the eye.
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