Abstract
BackgroundThe intraocular pressure (IOP) is maintained through a dynamic equilibrium between the production and drainage of aqueous humor. Elevation of intraocular pressure is mainly caused by the blocking of aqueous humor outflow pathway. Therefore, it is particularly important to study the structure of drainage pathway and the effect of ocular hypertension at the process of aqueous humor outflow.MethodsConventional drainage pathway of aqueous humor, including trabecular meshwork (TM), Schlemm’s canal (SC) and aqueous vein, were imaged by using trans-scleral imaging method with lateral resolution of 2 μm. For quantitative assessment, the morphological parameters of the TM were measured with different IOP levels via a combination of measurements and simulations.ResultsImages of the TM and the adjacent tissues were obtained. The porosity of TM with normal intraocular pressure varies from 0.63 to 0.74 as the depth increases, while in high IOP it is changed from 0.44 to 0.59. The diameter of aqueous vein varies from 32 to 43 μm, and is smaller than that of SC, which varies from 48 to 64.67 μm.ConclusionsOur research provides a non-contact method to visualize the microstructure of tissue for clinical examination associated with the blocking of the outflow pathway of aqueous humor in humans. The three-dimensional (3D) microstructures of limbus and the results of finite element modeling analysis of the TM model will serve for the future evaluation of new glaucoma surgical techniques.
Highlights
The intraocular pressure (IOP) is maintained through a dynamic equilibrium between the production and drainage of aqueous humor
Anterior segments consisting of cornea, anterior sclera, and trabecular meshwork with iris were prepared by cutting along the equator of the globe and placed in a culture dish with the TM side up for broken eye imaging
We can see that areas lacking signals are corresponding to the fluid-filled gaps, and the gaps seem to be heterogeneous with the depth increases
Summary
The intraocular pressure (IOP) is maintained through a dynamic equilibrium between the production and drainage of aqueous humor. Elevation of intraocular pressure is mainly caused by the blocking of aqueous humor outflow pathway. It is important to study the structure of drainage pathway and the effect of ocular hypertension at the process of aqueous humor outflow. Elevation of intraocular pressure (IOP) mainly caused by the blocking of aqueous outflow system is a high risk factor for glaucoma [3]. The pressure difference between inside (intraocular pressure, IOP) and outside (episcleral venous pressure, EVP) provides the force to make aqueous humor flow out of the TM [4]. During primary open angle glaucoma, the greatest resistance to aqueous humor flow is provided by the morphological changes in TM [5,6,7]. To clarify the production of outflow resistance, it is necessary to obtain the microstructure of drainage pathway
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