眼压测量与眼底图像动态采集系统设计

 眼疾的诊断与治疗中发现,青光眼是高眼压及昼夜变化引起的视神经头变质,是导致失明的第二大主因。只有发现眼压异常升高并伴有视野缺损和眼底视盘改变时,才可诊断为青光眼。因此,眼压和眼底血管网络是诊断青光眼的两个重要参数。本文基于Goldmann压平眼压计原理,实现通过单次测量同时获取眼压值与眼底图像。以FPGA为核心,通过光学探头触压角膜完成眼压测量与眼底图像的动态采集。眼压测量通过Nios II嵌入式软核控制驱动光学探头触压角膜的压力,利用角膜压平至一定面积时对应的压力获取眼压值。眼底图像的动态采集系统包括照明系统和观察系统两部分。照明系统选择柯拉照明,而观察系统通过图像传感器采集角膜压平图像和眼底图像,并上传至主机进行显示和保存等。该系统可以便捷有效地实现眼压值的计算与图像的实时动态采集、USB上传、显示与存储,提供青光眼诊断的两个重要指标。

The Design of Dynamic Acquisition System for Intraocular Pressure and Fundus Image

Glaucoma is the degeneration of the optic nerve head caused by elevated Intraocular Pressure (IOP) and diurnal variations. It is the second leading cause of blindness. The pathogen of glaucoma is very complex. Although abnormal elevation of IOP is the main reason, visual field defects and optic disc changes in eyes are also the symptoms. Therefore, IOP and fundus are two important and indispensable parameters for the diagnosis of glaucoma. Based on the principle of Goldmann applanation tonometer, the IOP measurement and fundus image are obtained by a single measurement. FPGA is the core unit of this design, the value of IOP and the acquisition of dynamic fundus images are measured by the optical probe which is pushed to contact the eye. IOP is measured by the software of Nios II which controls the probe pressure by using embedded soft-core. The value is indirectly calculated through selected appropriate algorithm of image segmentation for corneal flattening area. Design of dynamic fundus image acquisition system includes lighting system and observation system. The lighting system is made up of Cora lighting. The observation system acquires flattening corneal images and the fundus images in the process by means of imaging sensor. In order to verify the function of this system, the experiments, such as simulated eyeball and live animals, are carried out. The system is able to calculate IOP, acquire real-time dynamic images, and display and store images quickly and easily. It provides two important and indispensable parameters for the diagnosis of glaucoma.