Numerical Simulation Of Non-contact Tonometer Nozzle And Corneal Alignment System Research

In recent years, with the development of society and people living standard rise,more and more people begin to pay attention to their health problems. Among them, thehealth of the eye should not be ignored. Intraocular pressure is one of the importantprojects ophthalmologic examination and one of the important marks for the doctordiagnosis the health of the eye. Moreover, the monitoring and measurement ofintraocular pressure can effectively diagnosis and prevention major eye diseases such asglaucoma,which caused by pathologic ocular hypertension and it also has importantsignificance for other clinical diagnosis and treatment. For this reason, the experts andscholars in many countries of intraocular pressure measurement technology carried outresearch work.Tonometer as an important instrument to detect intraocular pressure, and it hasbrought great convenience for the doctor’s diagnosis.The nozzle of non-contacttonometer is such an important part of the testing instrument, and it is directly related tothe accuracy of the instrument measurement. But so far, the nozzle design research aremostly used in industry, agriculture, has the characteristics of large aperture, highpressure, high speed etal, and we have not see for research and application of themedical instrument especially for non-contact tonometer,which has the small nozzleaperture,low pressure jet nozzle design, and until now there is no research report. Basedon this, this paper uses COMSOL Multiphysics simulation the nozzle of the non-contacttonometer,which combine force balance principle and air static pressure technology,andit provides the basis of the numerical analysis for the nozzle structure size design ofnon-contact tonometer.The simulation results show that the optimum of the non-contacttonometer nozzle is located at radius of1mm, and20mm in length, the rated distancefrom the nozzle is10.5mm. The experimental results show that at this condition thenozzle of the Non-contact tonometer can provides an appropriate jet pressure range forthe intraocular pressure measurement when the spraying air flow deform the cornea to acertain diameter plane. It provided the foundation of numerical analysis for the structureand size of the nozzle of non-contact tonometer, the numerical simulation research ofNon-contact tonometer provides a valuable conclusion for the small diameter of lowpressure jet nozzle design, and it expanded the COMSOL Multiphysics simulationapplication research in medical instrument. This pape based on the measuring equipment of non-contact tonometer, whichcombine force balance principle and air static pressure technology, study and design thenon-contact tonometer measurement system.For the eye center image processing,we usefitting circle to calculate the center of the cornea, Then through the stepper motortwo-dimensional motion control, let the corneal center coordinates and the center of thenozzle coordinates in a straight line,so that the center of the cornea image can locationthe center position, which we can achieve the effect of accurate measuring intraocularpressure.