Mathematical Models of Aqueous Production, Flow and Drainage

Dvoriashyna, Mariia; Pralits, Jan O.; Tweedy, Jennifer H; Repetto, Rodolfo

doi:10.1007/978-3-030-25886-3_9

Cited by 5 publications

(4 citation statements)

References 59 publications

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“…The production of the AH mainly involves the collective effects of three driving pressures, including mechanical pressure, oncotic pressure and osmotic pressure. 115 First, the mechanical pressure (of approximately 15 mmHg) refers to the intrinsic pressure drop between the stroma and the AH, which originates from the capillary blood pressure and tends to drive fluid into the posterior chamber. Second, the oncotic pressure is mainly established by the differences in protein concentrations.…”

Section: Microfluidic Modelling Of Glaucomamentioning

confidence: 99%

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Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Fang,

Bi,

Brown

et al. 2023

Lab Chip

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Section: Microfluidic Modelling Of Glaucomamentioning

confidence: 99%

“…Combing the above three mechanisms, the ciliary epithelium's volumetric flow rate Q AH can be expressed as follows. 115 Q AH = A p L p (Δ p − σ p RT Δ c p + σ s RT Δ c s )…”

Section: Microfluidic Modelling Of Glaucomamentioning

confidence: 99%

Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Fang,

Bi,

Brown

et al. 2023

Lab Chip

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show abstract

“…Fluid-dynamical studies have the goal of predicting distributions of pressures and velocities characterizing the flow of a fluid in the tissue. In the eye, such studies have focused on the flow of blood, aqueous humor and tear film, with few contributions considering the dynamics of vitreous humor and cerebrospinal fluid, as reviewed in recent works (Arciero et al, 2019 ; Braun et al, 2019 ; Dvoriashyna et al, 2019 ; Repetto and Dvoriashyna, 2019 ; Sala et al, 2019b ).…”

Section: Overview Of Mechanism-driven Models Of the Eye And Their mentioning

confidence: 99%

Neurodegenerative Disorders of the Eye and of the Brain: A Perspective on Their Fluid-Dynamical Connections and the Potential of Mechanism-Driven Modeling

et al. 2020

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Neurodegenerative disorders (NDD) such as Alzheimer's and Parkinson's diseases are significant causes of morbidity and mortality worldwide. The pathophysiology of NDD is still debated, and there is an urgent need to understand the mechanisms behind the onset and progression of these heterogenous diseases. The eye represents a unique window to the brain that can be easily assessed via non-invasive ocular imaging. As such, ocular measurements have been recently considered as potential sources of biomarkers for the early detection and management of NDD. However, the current use of ocular biomarkers in the clinical management of NDD patients is particularly challenging. Specifically, many ocular biomarkers are influenced by local and systemic factors that exhibit significant variation among individuals. In addition, there is a lack of methodology available for interpreting the outcomes of ocular examinations in NDD. Recently, mathematical modeling has emerged as an important tool capable of shedding light on the pathophysiology of multifactorial diseases and enhancing analysis and interpretation of clinical results. In this article, we review and discuss the clinical evidence of the relationship between NDD in the brain and in the eye and explore the potential use of mathematical modeling to facilitate NDD diagnosis and management based upon ocular biomarkers.

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“…It is primarily caused by the abnormal accumulation of aqueous humor within the eye, leading to elevated intraocular pressure (IOP) and consequent overstress and damage to the optic nerve. Aqueous humor is produced in the posterior chamber of the eye; it flows into the anterior chamber through the gap between the iris and the lens, and is subsequently drained out through two typical pathways, namely, the trabecular meshwork and the uveoscleral pathway 3,4 (Figure 1a). Currently, IOP remains the most critical and modifiable risk factor in glaucoma.…”

Section: Introductionmentioning

confidence: 99%

Droplet Laplace valve‐enabled glaucoma implant for intraocular pressure management

Wang,

Fang,

et al. 2024

Droplet

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Glaucoma, the leading cause of irreversible blindness worldwide, is closely linked to aqueous overaccumulation and elevated intraocular pressure (IOP). For refractory glaucoma, aqueous shunts with valves are commonly implanted for effective aqueous drainage control and IOP stabilization. However, existing valved glaucoma implants have the disadvantages of inconsistent valve opening/closing pressures, poor long‐term repeatability due to their reliance on moving parts, and complex architectures and fabrication processes. Here, we propose a novel valving concept, the droplet Laplace valve (DLV), a three‐dimensional printable moving‐parts‐free microvalve with customizable and consistent threshold valving pressures. The DLV uses a flow discretization unit governed by capillarity, comprising a droplet‐forming nozzle, and a separated reservoir to digitize continuous flow into quantifiable droplets. Unlike the classic one‐time‐use Laplace valves, the DLV's unique design allows for its reusability. The opening pressure is adjustable by varying the nozzle size, like the classic Laplace valves (following the Young–Laplace equation), while the closing pressure can be modified by tuning the separation distance and the reservoir size. Various DLVs with customizable opening pressures from 5 to 11 mmHg have been demonstrated, with opening/closing pressure differences suppressed down to <0.5 mmHg (<0.15 mmHg under the best conditions). Thanks to its moving‐parts‐free nature and digitized flow properties, the DLV shows a highly repeatable valving performance (<1.7%, 1000 cycles) and a predictable linear flow rate–pressure correlation (R2 > 0.99). Preliminary ex vivo validation in an enucleated porcine eye confirms the DLV's efficiency in aqueous shunting and prompt IOP stabilization. The DLV technology holds great promise in glaucoma implants for IOP management and various microsystems for flow control.

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Mathematical Models of Aqueous Production, Flow and Drainage

Cited by 5 publications

References 59 publications

Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Neurodegenerative Disorders of the Eye and of the Brain: A Perspective on Their Fluid-Dynamical Connections and the Potential of Mechanism-Driven Modeling

Droplet Laplace valve‐enabled glaucoma implant for intraocular pressure management

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