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背景:目前的眼屈光度测量方法均采用红外LED发光二极管作光源,红外光通过人眼角膜、房水、晶状体、玻璃体以及视网膜,造成反射的眼底图像不均匀,边缘判别难免出现误差,影响测量结果。目的:为了解决人眼屈光度测量方法和精度问题,设计了一套基于图像处理的眼睛屈光度测量系统。方法:将六点红外光射入眼底,经光学系统接收成像在CCD上,首先利用自适应多阈值方法对图像进行二值化分割,然后用重心法求每个点的中心坐标,最后再用最小二乘拟合的方法计算眼睛屈光度。实验用标准模拟眼进行了测试,并同日本TPCON验光仪进行了比较。结果与结论:设计的眼睛屈光度测量系统测量精度能达到国家计量规定的±0.25m-1。避免了由于人眼系统结构造成CCD接受图像不均匀而导致的计算精度误差;系统结构简单,光源能量能满足需要,实验表明可以提高眼睛屈光度参数测量精度,利用该技术已经做出了样机。在医院临床快速检查、普查视力具有重要应用。不足之处在于结构简化,大屈光度测量容易造成误差,对光源同光学系统的同轴性要求高,这是以后设计和工艺需要改进的地方。
BACKGROUND: Current methods for measuring refractive power of the eyes all adopt infrared LED light-emitting diodes as the light source. Infrared light passes through the cornea, aqueous humor, lens, vitreous body and retina of the human eye, resulting in uneven reflection of fundus images. . OBJECTIVE: To solve the problem of the measurement method and accuracy of the human eye’s diopter, a set of eye-diopter measurement system based on image processing is designed. Methods: The six-point infrared light was injected into the fundus and received by the optical system on the CCD. Firstly, the image was binarized by adaptive multi-thresholding method, and then the center coordinates of each point were calculated by gravity method. Finally, The method of least square fitting calculates the eye refractive power. The experiment was conducted with a standard simulated eye and compared with a Japanese TPCON refractometer. RESULTS AND CONCLUSION: The designed eye refractive power measurement system can achieve the measurement accuracy of ± 0.25m-1 according to the national measurement. Which avoids the calculation accuracy error caused by the uneven image of the CCD which is accepted by the human eye system. The system has a simple structure and the energy of the light source can meet the need. Experiments show that the accuracy of the eye refractive parameter measurement can be improved, and the prototype has been made by using the technology. Rapid clinical examination in the hospital, census vision has important applications. Shortcomings in the structure is simplified, large diopter measurements easily lead to errors, the same optical system with high light source requirements, which is the future design and process needs to be improved.