| Aqueous humor(AH)is a constantly flowing transparent liquid in anterior human eye,which can influence drug delivery by convection.Meanwhile,AH flow makes corneal endothelium cells subjected to flow shear stress.Anomalous AH flow can lead to the change of flow shear stress on corneal endothelium cells,which results in changes of corneal cellular morphology and biological characteristics,and then cause keratopathy.Hence,a deeper understanding of AH dynamics and drug delivery in human eye would help to explore best application method of ophthalmic drugs and surgery,which can improve the treatment effectiveness and reduce the side effects on human tissues.Aiming at solving the problems mentioned above,the main contents in this thesis are listed as follows:(1)A numerical model of AH dynamics is established with heat transfer and AH flow in human eye.Temperature and velocity distribution are obtained.Numerical results show that natural convection plays a dominant role in AH flow.Furthermore,effects of eye position and ambient temperature on AH flow are discussed.Eye position can change the profile of AH flow,and the magnitude of AH velocity is greater in a horizontally-facing eye than in an up-facing eye.When the ambient temperature is close to body temperature,AH flows the most slowly.(2)Anterior eye diseases are commonly treated by topically applied drugs in the form of eye drops or ointment.A numerical model of topical drug transport in the anterior human eye is developed,which is coupled with heat transfer and AH flow in the anterior eye.Spatio-temporal evolution of drug concentration is then investigated numerically.Effects of eye orientation,means of drug administration and ambient temperature are also analyzed.We find it is not conducive to drug delivery when ambient temperature is close to human body temperature,and it can increase the amount of medication into the eye by increasing the residence time of drugs on ocular surface.Eye orientation is also found to influence the maximum drug concentration at different targets,as well as the time consumption for reaching the maximum level.(3)A computational model is developed,which includes heat transfer,aqueous humor flow,as well as diffusive and convective transport of the drug concentration,to study the temporal-spatial evolution of drug concentration in the anterior segment of a human eye after subconjunctival and episcleral drug implantation.Numerical results indicate that subconjunctival implantation is more effective than episcleral implantation for drug delivery to drug targets.Circumferential location of the implant also influences delivery efficacy.Drug implantation at 12 o’clock position is the most conducive for drug delivery to iris and lens,and 3 o’clock position implantation is the most effective way for drug transport to TM.Furthermore,drug delivery is more effective in a horizontally-facing eye compared with an up-facing eye.(4)To study the influence of Laser Peripheral Iridectomy(LPI)on aqueous humor flow in the eyes of patients and fluid shear stress exerted on corneal endothelial cells,a complete three-dimensional geometric eye model is established.Numerical simulations on the flow conditions of aqueous humor and the shear stress exerted on corneal endothelial cells after LPI surgery are performed using finite element software.The simulation results at different positions of the laser hole in the iris before and after LPI surgery are compared.When the laser hole in the iris is punched closer to the pupil axis,the shear stress exerted on corneal inner surface become smaller.(5)A fluid stress loading device for cells on the surface deformation is designed.The elastic transparent film can achieve deformation by the pressure from by pressure chamber,and thus the device can change its bottom shape of the flow chamber,and hence regulate the stress exerted on biological cells.Thus,observation and detection of changes of cell morphology and biological properties under different loading conditions can be achieved. |
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