Non-invasively quantifying retinal oxygen saturation by visible-light optical coherence tomography

Project: Research project

Description

Diabetic retinopathy (DR) is a major complication of diabetes that can lead to blindness. The late stage of diabetic retinopathy is characterized by the formation of new retinal capillaries and the leakage of blood vessels in the eye. The leaked blood eventually can block the light and cause blindness. It has been hypothesized that the early signs of the diabetic retinopathy include the elevated metabolic rate of oxygen. There are two central steps in oxygen metabolic rate quantification: oxygen saturation (sO2) and blood flow (mL/min) in retinal vessels. Although optical techniques have been developed to measure blood flow, no existing technique allows non-invasive quantification of sO2 in retina. Hence, we propose here to test the feasibility of using a novel functional imaging technique, called visible-light optical coherence tomography (vis-OCT), to quantify the retinal sO2. In red blood cells, oxygen is carried by hemoglobin (Hb). When oxygen is bonded to Hb, the hemoglobin is oxygenated as oppose the deoxygenated Hb, where oxygen is detached. The percentage of oxygenated hemoglobin out of the total hemoglobin is quantified by sO2. Because the absorption spectra of oxygenated and deoxygenated Hb are different, sO2 can be deduced by analyze the absorption spectrum from blood. The vis-OCT technique we propose to use here is a non-invasive three-dimensional imaging technique analogous to ultrasound. In order to detect the echo light from different depth of tissue, a broad band light source is required. Thus from a particular structure (i.e. bottom wall of retinal blood vessels), a spectral profile can be extracted and analyzed to deduce sO2.
StatusFinished
Effective start/end date7/1/136/30/14

Funding

  • Illinois Society for the Prevention of Blindness (AGMT-12/11/13)

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hemoglobin
tomography
saturation
oxygen
blindness
blood vessels
blood flow
imaging techniques
blood
absorption spectra
retina
erythrocytes
vessels
echoes
light sources
leakage
broadband
causes
profiles