Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter.The human retina is a thin and multiple layer tissue,and the layer of capillaries less than10 μm in diameter only exists in the inner nuclear layer.The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rodcone cell surface is tens of micrometers,which varies from person to person.Therefore,determining reasonable capillary layer(CL) position in different human eyes is very difficult.In this paper,we propose a method to determine the position of retinal CL based on the rodcone cell layer.The public positions of CL are recognized with 15 subjects from 40 to 59 years old,and the imaging planes of CL are calculated by the effective focal length of the human eye.High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system(LCAOS) validate our method.All of the subjects' CLs have public positions from 127 μm to 147 μm from the rodcone cell layer,which is influenced by the depth of focus.     

抑制眼内杂散光提高视网膜成像质量方法研究

利用液晶空间光调制器和夏克-哈特曼探测器为核心器件搭建了一套液晶自适应光学(AO)视网膜成像系统。通过计算哈特曼光斑图和视网膜图像的调制传递函数(MTF)定量分析了眼内杂散光对视网膜成像质量的影响,结果表明哈特曼光斑图的MTF优于视网膜图像的MTF,说明眼内杂散光降低了视网膜的成像质量。根据眼内散射光偏振状态改变的特点,系统采用偏振光照明,抑制眼内散射光;利用补偿镜和位于眼前1m位置处的视标,使照明光准确聚焦在视网膜血管层上,抑制视网膜多层组织反射杂光。通过对比实验,证明以上方法在一定程度上抑制了眼内杂散光对视网膜成像质量的影响。最后对4名志愿者进行了视网膜血管自适应成像实验,均获得了清晰的眼底视网膜血管图像。