Research Of Aqueous Humor Dynamics In The Human Eye Based On The AS-OCT Images And Lattice Boltzmann Method

The flow of aqueous humor in the human eye plays a key role in maintaining the normal physiological function of human eyes.Once the outflow of aqueous humor is blocked,the intraocular pressure will increase,which will lead to glaucoma and other ophthalmic diseases.Therefore,it is of great significance to study the mechanism of human eye's aqueous humor dynamics to explore the physiological structure of human eyes,the pathogenesis of ophthalmic diseases and their treatment methods.At present,many scholars have carried out extensive research on human aqueous humor dynamics and made a lot of achievements,which laid a solid foundation for the in-depth study of human aqueous humor dynamics.In previous studies,most of the geometric models of the anterior segment of the human eye were ideal simplified models based on the parameters of the anatomical structure of the human eye,so the simulated results may be deviated from the actual situation.Moreover,studies on the aqueous humor dynamics of the human eye based on the real structure of the anterior segment of the human eye were rare.On the other hand,the traditional computational fluid mechanics methods,such as finite element method and finite volume method,are generally used in the numerical study of human eye's aqueous humor dynamics.These methods are difficult to deal with complex geometric boundaries and have low computational efficiency.Therefore,based on the real structure of the anterior segment,a better result may be obtained by using the appropriate numerical simulation method to study the human aqueous humor dynamics.Optical coherence tomography(OCT)is a new type of imaging technology.Compared with other ophthalmic imaging technologies,the OCT images of the anterior segment of the eye can accurately represent the tissue structure of the anterior segment,have laid the foundation to establish a real geometric model of the anterior segment and to conduct personalized research on the aqueous humor dynamics of the human eye.As a mesoscopic numerical simulation method,the lattice Boltzmann(LB)method combines the characteristics of micro and macro methods,and has been successfully applied in the fields of biological flow,particle flow and multiphase flow.The scale of most eye tissues is on the order of millimeters,which is just right for the mesoscopic LB method.For the complex anatomical structure of the human eye,diverse flow patterns,and coexistence of multiple physical processes,the advantages of the LB method such as clear physical background and easy handling of complex boundaries provide good premises for solving the problem.In addition,the natural parallel nature of the LB method ensures that the study of the hydrodynamics of the human eye can achieve efficient numerical simulation.Therefore,the LB method is very suitable for the study of the aqueous humor dynamics of the human eye.In this paper,the image processing technology is first used to process the OCT image of the anterior segment,The image denoising method based on the LB anisotropic diffusion model is used to complete the image denoising,the edge detection method based on the LB isotropic diffusion model is used to extracte the geometric contour of anterior segment,and the posterior segment and other structures are reconstructed according to the anatomical parameters of the human eye,and a geometric model that can be used for LB numerical simulation is established.Then,the aqueous humor dynamic model of the human eye based on the LB method is proposed,including the use of the incompressible Navier-Stokes equation to describe the flow of aqueous humor in the anterior and posterior chambers,and the use of the convective diffusion equation to describe the heat transfer process of aqueous humor,and Darcy's law is used to describe the process of aqueous humor penetrating trabecular network,and the Boussinesq approximation is used to complete the coupling among the three.Next,the accuracy and stability of the current model were verified by two experiments of two-dimensional square cavity natural convection and ideal model of human eye chamber hydrodynamics.Finally,based on the geometric model created by the OCT image of the anterior segment of the normal human eye,the verified model was used to simulate the aqueous humor dynamics in the human eye,and eddy currents in the iris crypt were observed.At the same time,the effects of intraocular temperature difference,anterior chamber cavity shape,cornea deformation,pupil size,iris shape and anterior chamber angle size on the aqueous humor dynamics of the human eye were analyzed,it was concluded that the intraocular temperature difference is linearly related to the maximum flow rate of aqueous humor,the shape of the iris will significantly change the shear stress distribution at the iris,and people with narrow anterior chamber angles have a higher risk of disease.In conclusion,the human eye aqueous humor dynamics based on the OCT image of the anterior segment and LB method can more accurately reflect the aqueous humor flow in the real human eye,and obtain some physiological and pathological parameters that are difficult to be directly measured,which can provide a numerical theoretical reference for ophthalmology.The human eye's aqueous humor dynamics is a cross-cutting field that combines computer science,fluid mechanics and ophthalmology.Using advantage of the LB method in dealing with complex fluid motion problems,further research on it is expected to achieve more meaningful results.