Optical coherence tomography is non-invasive diagnostic technique for performing high resolution (~µm) cross sectional imaging. In this article, we demonstrate characterization and oxygen saturation studies of human retinal blood vessels with Principal Component Analysis (PCA) based Spectroscopic Optical Coherence Tomography-based Angiography. A Fourier Domain Mode-Locked laser having an axial imaging resolution of ~7.5 µm, with an A-scan sweep rate of 1.7 MHz and centre wavelength of 1060 nm, was utilized as an OCT source. PCA has been used in conjunction with a scanning Short Time Fourier Transform, procedure to isolate the probable amount of oxygenated and deoxygenated haemoglobin and extract the information from individual OCT frames, without any external fitting model. This technique could provide useful insight into an effective blind source data extraction technique for medical image analysis. The technique proposed in this article, has a significant advantage in requiring no additional filtering or noise reduction technique in order to accurately extract the required information. It can also be used for ophthalmological research to determine the oxygen saturation of human retinal blood circulation, which may be helpful for identification of abnormalities related to human eye.