It is very difficult to measure the human eye properties directly, such as the accommodation mechanism, intraocular pressure distribution, the dynamics of aqueous humor flow and the bio-heat transfer in human eyes. Modeling and simulation may, therefore, play an increasingly important role in the ophthalmologic investigation. The major computer modeling methods, including geometric modeling, physical modeling and mathematical modeling, are introduced in this paper. Modeling and simulation anatomy properties and physiological properties of eye tissues, such as the cornea, aqueous humor and crystalline lens, vitreous, optic nerve head, sclera, are analyzed in the order from global to local, from front to back, from outside to inside. Finally, the problems of computer modeling in ophthalmologic investigation are discussed, and the development trends of the future are pointed out.
Aqueous Humor ; physiology ; Computer Simulation ; Cornea ; physiology ; Eye ; anatomy & histology ; Humans ; Lens, Crystalline ; physiology ; Ophthalmology ; trends ; Sclera ; physiology

A three-dimensional (3D) model of human anterior chamber is reconstructed to explore the effect of different corneal temperatures on the heat transfer in the chamber. Based on the optical coherence tomography imaging of the volunteers with normal anterior chamber, a 3D anterior chamber model was reconstructed by the method of UG parametric design. Numerical simulation of heat transfer and aqueous humor flow in the whole anterior chamber were analyzed by the finite volume methods at different corneal temperatures. The results showed that different corneal temperatures had obvious influence on the temperature distribution and the aqueous flow in the anterior chamber. The temperature distribution is linear and axial symmetrical around the pupillary axis. As the temperature difference increases, the symmetry becomes poorer. Aqueous floated along the warm side and sank along the cool side which forms a vortexing flow. Its velocity increased with the addition of temperature difference. Heat fluxes of cornea, lens and iris were mainly affected by the aqueous velocity. The higher the velocity, the bigger more absolute value of the above-mentioned heat fluxes became. It is practicable to perform the numerical simulation of anterior chamber by the optical coherence tomography imaging. The results are useful for studying the important effect of corneal temperature on the heat transfer and aqueous humor dynamics in the anterior chamber.
Anterior Chamber ; physiology ; Aqueous Humor ; physiology ; Cornea ; physiology ; Humans ; Iris ; Lens, Crystalline ; Models, Biological ; Temperature ; Tomography, Optical Coherence

No abstract available.
Adult ; Female ; Glaucoma, Angle-Closure/*surgery ; Humans ; Intraocular Pressure/physiology ; *Iridectomy ; Iris/*surgery ; Laser Therapy/*methods ; Lens, Crystalline/*physiology ; Middle Aged ; Suture Techniques ; Tonometry, Ocular ; Viscosupplements/administration & dosage

PURPOSE: In this study, we examined the stability of the lens-angle supporter (LAS) for accommodation restoration by comparing intraocular lens (IOL) location, after-cataract and ciliary body damage after cataract surgery in rabbits. METHODS: Eight rabbits were divided into experimental and control groups of four rabbits each. Phacoemulsification and irrigation and aspiration were performed in all rabbits. This was followed by an LAS and IOL insertion in the four experimental rabbits. In the four control rabbits, only an IOL insertion was performed. Six months after the surgery, the location of the IOL, the conditions of the lens capsule and ciliary body were evaluated using a slitl-amp examination and Miyake-Apple view. RESULTS: For the experimental group, the ultrasound biomicroscope results showed normal LAS and IOL positioning in all four cases. According to the slitlamp examination and Miyake-Apple view, the IOL was positioned at the center, with less after-cataract and damage to the ciliary body. For the control group, ultrasound biomicroscope results indicated a higher IOL position than normal, as well as a single case of IOL decentering. According to the slit-lamp examination and Miyake-Apple view, the IOL was decentered with more severe after-cataract and ciliary body damage. CONCLUSIONS: The LAS has the potential to maintain a stable IOL position while producing less after-cataract when used in lens-angle reconstruction for correction of presbyopia. Moreover, LAS implantation incurs less damage to the ciliary body.
Accommodation, Ocular/physiology ; Animals ; Anterior Eye Segment ; Ciliary Body/injuries ; Disease Models, Animal ; Eye Injuries/*surgery ; Lens Capsule, Crystalline/*surgery ; *Lens Implantation, Intraocular ; Microscopy, Acoustic ; *Phacoemulsification ; Rabbits ; *Reconstructive Surgical Procedures

PURPOSE: The purpose of this study is to understand the mechanism of apoptosis occurring on a cultured human lens epithelial cell line after exposure to ultraviolet (UV) light. We intended to confirm the presence of cellular toxicity and apoptosis and to reveal the roles of p53, caspase 3 and NOXA in these processes. METHODS: Cells were irradiated with an ultraviolet lamp. Cellular toxicity was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hoechst staining and fluorescent anti-caspase 3 antibodies were used for apoptosis investigation. The quantities of p53, caspase 3, and NOXA were measured by Western blotting for to investigate the apoptosis pathway. RESULTS: Cellular toxicity on the human lens epithelium markedly increased with time after UV exposure. On Hoechst staining, we found that apoptosis also remarkably increased after exposure to ultraviolet light, compared with a control group. In the immunochemical study using anti-caspase 3 antibodies, active caspase 3 significantly increased after exposure to ultraviolet light. On Western blotting, p53 decreased, while caspase 3 and NOXA increased. CONCLUSIONS: Exposure of cultured human lens epithelial cell lines to ultraviolet light induces apoptosis, which promotes the expression of NOXA and caspase 3 increases without increasing p53. This may suggest that UV induced apoptosis is caused by a p53-independent pathway in human lens epithelial cells.
Apoptosis/*physiology ; Caspase 3/metabolism ; Cell Line ; Cell Survival/radiation effects ; Epithelial Cells/radiation effects ; Humans ; Lens, Crystalline/cytology/*physiology/*radiation effects ; Proto-Oncogene Proteins c-bcl-2/metabolism ; Tumor Suppressor Protein p53/metabolism ; *Ultraviolet Rays

BACKGROUNDEquatorial lens epithelial cells proliferate and differentiate into fiber cells throughout life, while central lens epithelial cells proliferate little and do not form fiber cells. This study aimed to investigate the differences in gene expression between the central and the peripheral epithelial cells of the bovine lens.

METHODSLens epithelia were dissected into central (

RESULTSBy microarray analysis, 67 transcripts were at least two-fold lower and 269 at least two-fold higher in pLEC compared with that in cLEC. Thirty-four protein spots, including 20 in cLEC and 14 in pLEC, were identified by two dimensional electrophoresis and mass spectrometry. Of these 34 protein products, 28 were represented by probe sets on the microarray. Nine transcripts changed in the same direction and four transcripts in the opposite direction to their protein products. Immunoanalyses revealed that three (mitogen-activated protein kinase 1 (MAPK1), nidogen (NID), small nuclear ribonucleoprotein N (SNRPN)) out of four transcripts with opposite change between 2-DE and microarray assay showed the same changes as the results of 2-DE gel analyses. The genes differently expressed between cLEC and pLEC mainly include those related to the MAPK, transforming growth factor beta (TGFbeta) signaling and glycolysis pathways.

CONCLUSIONThe results suggested that there were distinctly different genome activities, including a specific group of pathways, between central and peripheral lens epithelial cells.

Animals ; Cattle ; physiology ; Electrophoresis, Gel, Two-Dimensional ; Epithelium ; metabolism ; Gene Expression Profiling ; Gene Expression Regulation ; In Vitro Techniques ; Lens, Crystalline ; metabolism ; Oligonucleotide Array Sequence Analysis ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

OBJECTIVETo investigate the role of caspase-3 and its inhibitor Ac-DEVD-CHO in rat lens epithelial cell apoptosis induced by hydrogen peroxide (H(2)O(2)) in vitro.

METHODSRat lenses were incubated in modified Eagle's medium containing 2 mmol/L H(2)O(2) to induce apoptosis in vitro. Apoptosis in lens epithelial cells was assessed by transmission electron microscopy and annexin V-propidium iodide (PI) double staining flow cytometry after 12, 24 and 48 h of incubation. The activity of caspase-3 was analyzed by western blotting.

RESULTSObservations under transmission electron microscopy revealed that 2 mmol/L H(2)O(2) could effectively induce lens epithelial cell apoptosis in vitro. Caspase-3 activity increased during cell apoptosis and the peak measurement occurred at 24 h after treatment with H(2)O(2). Cell apoptosis was blocked by caspase-3 inhibitor Ac-DEVD-CHO.

CONCLUSIONSThe activation of caspase-3 plays an important role in executing apoptosis in H(2)O(2)-treated lens epithelial cells and in the formation of cataract. The caspase-3 inhibitor Ac-DEVD-CHO may effectively prevent lens epithelial cell apoptosis caused by oxidative injury.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; Caspase Inhibitors ; Caspases ; metabolism ; physiology ; Cysteine Proteinase Inhibitors ; pharmacology ; Enzyme Activation ; Epithelial Cells ; cytology ; Female ; Hydrogen Peroxide ; pharmacology ; Lens, Crystalline ; cytology ; Oligopeptides ; pharmacology ; Organ Culture Techniques ; Rats ; Rats, Sprague-Dawley

An after-cataract is caused by the proliferation of residual cells over the equator of the lens. These cells subsequently migrate to the posterior lens capsule, where they undergo aberrant differentiation into fiber-like cells or transdifferentiation into fibroblast-like cells. To study the precise molecular mechanisms of transdifferentiation, an attempt was made to establish an in vitro system, in which the lens epithelial cells (LECs) of the pre-equatorial zone could be transdifferentiated into fibroblast-like cells. The required conditions for culturing the LECs were identified as consisting of four phases; intact bovine explants, explant-cultured, serum-modulated and additionally modulated LECs. The LECs of each phase were compared by examining changes in the expression of the epithelial-mesenchymal transition (EMT) -related genes and changes in cellular morphology and adhesion. The explants that were cultured in a medium containing 10% fetal bovine serum (FBS) for 2 weeks, showed changes in the expression of the EMT-related genes, although the other explant-cultured cells maintained an epithelial morphology. To introduce a transition into mesenchymal cells, the explant cultures were subcultured in a medium containing 20% FBS for six passages. These cells displayed an elongated morphology and were able to grow and migrate in a similar way to fibroblast cells. The expression of the EMT-related genes, such as, extracellular matrix proteins and integrins, was altered. This was similar to the alteration of the 3-dimensional collagen gels model previously reported. During a further process of EMT by additional serum modulation, the inhibitory effect of disintegrin on cell adhesion was gradually decreased, integrin expression was differentially regulated and alpha-smooth muscle actin was post-translationally modified from the point of passage number six. Overall, it can be concluded that terminal transdifferentiation accompanies changes in the cytoskeletal proteins and cell surface molecules. These are modulated in systematic patterns of post-transcriptional and post-translational regulation and patterns of gene regulation, by the synergic effects of several transforming factors contained in serum. Therefore, posterior capsular opacification may also be accompanied by this molecular mechanism.
Animals ; Blood Proteins/*pharmacology ; Cattle ; Cell Adhesion/drug effects ; Cell Differentiation/drug effects/physiology ; Cells, Cultured ; Epithelial Cells/*cytology/physiology ; Fibroblasts/*cytology/physiology ; Gene Expression/drug effects ; Lens, Crystalline/*cytology ; Support, Non-U.S. Gov't ; alpha-Crystallin A Chain/genetics ; alpha-Crystallin B Chain/genetics