基于单镜头反光式照相机的视网膜血氧饱和度无创测量系统

he retina is a biological tissue with high oxygen metabolism. When there is an ocular lesion or systemic disease of the human body, typically there are abnormal retinal blood oxygen metabolism and regulating disorders correspondingly. However, conventional fundus imaging technique can only display the direct structural information of the fundus, it cannot measure the functional information such as the blood oxygenation level within retinal vessels. Currently, scientific-grade detectors are generally employed in both commercially developed instruments and laboratory prototypes that allow for the non-invasive detection of retinal oxygen saturation. However, these scientific-grade detectors are very expensive and to some extent it hinders the mass production and sales of the retinal oxygen saturation measurement instruments. Meanwhile, these instruments mentioned above are usually modified on the main body of conventional fundus imaging instruments such as the fundus camera, which brings huge extra work such as redesigning the optical path, hardware interface and the software control of the additionally equipped scientific-grade detectors. Furthermore, as the added scientific-grade detectors are usually large in size, it can cause a huge change in the center of gravity of the instrument as well as its appearance, which brings inconvenience to the device operators. In this study, a non-invasive retinal blood oxygen saturation measurement system is designed based on a conventional fundus camera with the single-lens reflex (SLR) camera as the detector. Specifically, the Nikon D70 SLR camera is used as the detector in the system for its ideal spectral response curves of the green and red channels. By extracting the corresponding retinal imaging information on the green and red channels, the functional blood oxygen saturation can be further calculated through a lab developed software. The method proposed in this study avoids the complicated and expensive modification of the conventional fundus camera, which greatly reduces the cost of the non-invasive retinal oxygen saturation measurement. In addition, it is also convenient for operating the device for doctors and researchers. The experimental results show that the system is able to measure the oxygen saturation with good accuracy and repeatability. The proposed method offers a new idea for the economic version of the retinal oxygen saturation measurement system, and it has the potential for further study and clinic applications associated with ophthalmic and systemic diseases.