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Anhtuan Hoang Nguyen, Jeffrey W Kiel; A mathematical model of aqueous humor dynamics and ocular pulse amplitude.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1065.
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© ARVO (1962-2015); The Authors (2016-present)
To depict steady state aqueous humor dynamics and the pulsatile nature of intraocular pressure (IOP) during physiological and non-physiological conditions utilizing a mathematical model. Studies have suggested that ocular pulse amplitude (OPA), which is defined as the difference between the maximum and minimum IOP, may play a role in glaucoma progression.
A mathematical model was developed in LabVIEW, a visual programming language (National Instruments, Austin, TX). The model establishes the relationships between ciliary and choroidal hemodynamics, passive and active process of aqueous production, aqueous outflow facility and the aqueous outflow via the trabecular and uveoscleral pathways, and the IOP. The pulsatility of the model is a polynomial function of heart rate and systemic blood pressure to simulate the arterial pulse. The model is consistent with current concepts of aqueous dynamics and has been validated by a number of in vivo studies.
The model depicts the pulsatile nature of IOP at different outflow facilities (figure 1). IOP increases nonlinearly as outflow facility decreases. The model shows that as IOP increases the OPA increases linearly (figure 2). At an average IOP of 18 mmHg the OPA is 3.3 mmHg while at an average IOP of 49 mmHg the OPA is 9.2 mmHg.
The model accurately simulates the pulsatile nature of aqueous humor dynamics in accordance with clinical observations. The model is useful to study aqueous dynamics parameters that are difficult to measure in vivo.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1: The effect on intraocular pressure (IOP) at different outflow facilities (C, µL/min/mmHg).
Figure 2: The ocular pulse amplitude increases as the intraocular pressure increases.
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