Study On Measurement And Device For Intraocular Pressure Non-contact Measuring Based On Aerostatic Technology

With the development of national economy and the modern medicine, the health of eyes has been paid more and more attention. Glaucoma in particular is one disease which can make the eye be blind, often called"lurk killer". For these reason, many developed country had done some research work on IOP measurement. The people initially adopt the contact measurements, but these kinds of measurement make the patient uncomfortable, and the patient need anaesthesia. At the same time, it can bring the infection among the patient. It is very un-convenient. For this reason, many countries had developed some non-contact measurement technologies, in particular the United States, Japan and other developed countries. They already have more sophisticated non-contact measurements of IOP. In our country a number of scholars also have put forward some new technologies. But these new technologies have not been used in the actual measuring IOP.Now these sophisticated technologies have been monopolized by foreign countries and the tonometers which based on these technologies are complex and costly. In the paper, a new non-contact measurement of IOP which using the principle of force balance has been put forward. This measurement is an indirect measurement of the pressure in the cornea. It is different from existing measurements which measuring IOP by algorithm of relationship between gas pulse duration and Initial pressure of gas cavity.A measuring device based on aerostatic technology has been designed in the paper. The measuring device is composed by several parts as follow: the air module for measuring IOP, the module of shell, the fine adjustment module of distance and the module of air supply. In particular, the design of the air module for measuring IOP is discussed. Through the research of air jet technology and air static pressure technology in the paper, Nozzle Shape has been choice and nozzle diameter and distance between the nozzle and Cornea has been calculated .And air cushion has been designed, which made the air module for measuring IOP suspending in the module of shell without solid friction.Measuring system which used AT89S51 MCU as main control part has been designed In this paper. The collectivity structure of hardware has been given. And the paper goes into particulars on each functional circuit of design and realization. The circuits are signal detection circuit of infrared photoelectric, signal detection circuit of pressure sensor, A/D circuit of data acquisition, D/A circuit of data output, circuit of display and circuit of keyboard. And control software was designed for each circuit in detail.At last, through the performance test and results analysis, primary experimental results indicates that the device based on aerostatic technology using the non-contact measurement of IOP should be feasible. And some disadvantages should be improved in the next work.