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Y. Yamamoto, T. Uno, A. Shiraishi, Y. Ohashi; Analysis of Aqueous Dynamics in the Shallow Anterior Chamber Eyes With Laser Iridotomy Using Computational Fluid Dynamics. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2806. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
In the laser iridotomy (LI) model of rabbit eyes, we demonstrated that the aqueous streaming through the LI window was generated during miosis, colliding against the corneal endothelium(1) . In this study, using computational fluid dynamics (CFD) software, we simulated the aqueous streaming of the LI eyes with the shallow anterior chamber models and calculated shear stress to the corneal endothelium.
Using CFD software FLUENT TM, three-dimensional anterior chamber models with various anterior chamber depth (ACD; 2.8, 1.8, 1.5, and 1.0mm) were constructed, and the flow speed of thermal current was calculated with the temperature of 36°C at the posterior corneal surface and 37°C at the iris surface. Then, a virtual LI window was created on the peripheral iris and the shear stress to the corneal endothelium was calculated using FLUENT TM. The maximum velocity of the forward aqueous streaming was set at 9.39 mm/s which is extrapolated from our previous animal experiments.
The descending speed near the corneal endothelium was 0.23, 0.11, 0.076, 0.037 mm/s, and the ascending speed near the anterior surface of the lens was 0.28, 0.12, 0.080, 0.034 mm/s in the eye model with 2.8, 1.8, 1.5, 1.0 mm ACD respectively, indicating that the thermal current speed was slower in the eye with shallower ACD. In the models with LI, the maximum shear stress to the corneal endothelium was 0.12, 0.28, 0.44, 0.68 dyne/cm2 in the eyes with 2.8, 1.8, 1.5, 1.0 mm ACD respectively, indicating that the shear stress was greater in the eyes with shallower ACD.
The current of aqueous humor tends to stagnate, the more shear stress to the corneal endothelium is created by aqueous streaming in the eyes with shallow anterior chamber. Such abnormal aqueous dynamics may augment the corneal endothelial decompensation.Ref.(1) Yamamoto Y et al. Arch Ophthalmol. 124:387-393. (2006)
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