Research On Key Technique Of Wide-area Digital Fundus Imaging Technology

With the development of ophthalmic medical equipment,retinal imaging has been more and more widely used,especially in the diagnosis and treatment of ophthalmic diseases.Traditional fundus examination method,is complex,it requires a high degree of cooperation between doctors and patients.The fundus camera to make up for these deficiencies,but still unable to achieve the peripheral retinal image acquisition.Wide-area retinal imaging system is based on the traditional fundus camera by improving lighting and imaging optical path,increasing the field of view.This article focuses on the wide-area fundus imaging system and it provids theoretical basis and practical guidance for the development of wide-area retinal acquisition system.The main contents of the thesis include:(1)A wide-area retinal imaging system was proposed based on the phenomenon of eye diseases such as ROP and complications such as diabetes mellitus in the peripheral region of the retina for the examination of lesions in the periphery of the fundus.Wide-area fundus takes image with ultra-wide-angle corneal contact lens imaging and ring light illumination.(2)To study the principle of wide-area retinal imaging,introduce a contact lens to increase the imaging field of view,analyze the optical characteristics of human eyes,and establish the Escudero-Sanz large field model eye for optical simulation.Based on the traditional structure of the fundus camera,a wide area imaging optical path is designed.The imaging optical path is analyzed by ZEMAX software at different field of view.By analyzing the simulation results,the imaging parameters of the lens and spatial position are adjusted to increase the angle of view field of imaging.(3)The LED of cold driving light source is selected by the imaging process according to the human eye safety standard,which forms the annular illumination light on the front surface of the corneal lens through the optical fiber conduction and whose larger refractive index forms the uniform refractive index on the fundus.The lighting process is simulated using The LightTools optics software to obtain the illuminance profile.Fundus camera case design based on lens parameters and spatial distribution of the lighting system and imaging system,including the mechanical structure of the focusing system.(4)A wide area retinal imaging operating system is designed based on the camera control system and electronic medical record library management system provided by the CMOS camera software development kit to realize the functions of image acquisition,analysis,archiving and querying.A set of experimental platform is built by combining the PC terminal with wide area imaging system,which is used to correct the optical parameters and validate the imaging results under actual conditions.A set of experimental platform was set up by combining the PC terminal with the wide area imaging system via Wi-Fi.The retina images with the simulated field of view angles greater than 103 ° were obtained and the experimental results were analyzed.