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Jabia Mostofa Chowdhury, Madhusudhanan Balasubramanian; Computational Modelling of Aqueous Humor Dynamics and Drug Delivery for Intraocular Pressure Control in Glaucoma. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4703.
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We present a computational model of sustained delivery of ocular pressure lowering drugs such as Timolol Maleate to the anterior segment of the eye using drug infused contact lens while simultaneously modeling the aqueous humor dynamics.
Transport of Timolol Maleate from contact lens to ocular structures (cornea, iris, and lens) in the anterior segment by diffusion and convective transport of the drug in the anterior chamber due to aqueous humor dynamics were modeled as a transport of diluted species in COMSOL 5.3. Ocular structures were modeled as linearly elastic solids and the aqueous humor production, flow dynamics and outflow were modeled as viscous fluid flow. The interaction between the ocular structures and aqueous humor dynamics were modeled using a fluid-structure interaction model with no slip boundary condition at the solid-fluid interface. Spatial distribution of aqueous flow dynamics (velocity) obtained from the FSI model was coupled with a drug diffusion model to account for convective transport and outflow of the drug through the trabecular meshwork. Both FSI and drug transport were assumed to be axisymmetric and corneal limbus, the root of the iris and the surface boundary of the lens and vitreous humor were considered as fixed boundaries in the model. Aqueous humor production in the ciliary body was simulated as an inlet with a mass flow rate of 10e-8 kg/s. We studied the drug diffusion model under normal intraocular pressure level (15 mmHg) and under an elevated level (20 mmHg). We compared the drug delivery to the anterior segment for a period of 1000 seconds. Drug transport in the diffusion-FSI coupled model was compared to the transport characteristics of the diffusion model with a reaction term alone for drug loss in the aqueous humor.
Fig 1 shows aqueous humor dynamics and fig. 2 shows drug transport characteristics with and without explicit aqueous humor modeling. It is apparent that accounting for aqueous humor dynamics provided a more accurate spatial transport and distribution of the drug near the outflow facility.
The coupled FSI-diffusion model accounting for aqueous humor dynamics provided a more accurate spatial transport and distribution of the drug. The presented model may be useful to more accurately model and study various ocular drugs and their delivery to the anterior and posterior segment of the eye.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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