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V.H. Barocas, E.C. Huang; Computer Simulation of Iris Contour During Dilation . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3662.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the dynamic mechanical interaction between aqueous humor and iris during dilation, with specific relevance to dark room provocative testing. Methods: Our previous steady–state model, which incorrectly predicted an increase in angle with increased pupil size, has been modified to account for dynamics of the dilation process. The new model accounts for the dynamic behavior by introducing a time–dependent extra stress in the sphincter and dilator. The model accounts for mechanics of the iris and fluid dynamics of the aqueous. The resulting partial differential equation system is solved by the finite element method. Results: The transient case showed a significant difference from the steady–state case. Also of interest, the response of the model varied considerably depending on whether the sphincter or dilator was used to generate motion. That is, decreasing the stress in the sphincter and increasing the stress in the dilator did not produce the same results when combined with the aqueous flow, even though the equilibrium pupil diameter would have been the same in both cases. Conclusions: Dynamic behavior should be considered when evaluating dark room testing, and more information about the precise muscular contributions to pupil size is needed for future models.
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