Numerical simulations of ethacrynic acid transport from precorneal region to trabecular meshwork

Fish Fin-Derived Non-Invasive Flexible Bioinspired Contact Lens for Continuous Ophthalmic Drug Delivery

Efficient drug delivery is crucial for glaucoma patients. Flexible biomedical devices that enable sustained ocular drug delivery and can regulate the drug release rate according to physiological conditions are highly desirable for glaucoma treatments, addressing both low drug bioavailability and poor patient compliance from manual drug administration, and improving treatment outcomes. Inspired by the structure and reciprocating motion of fish dorsal fins, a drug-eluting contact lens based on deformable microstructures for non-invasive ocular surface drug delivery is developed. Liquid drugs are stored within the interstices of the deformable microstructural units, allowing for continuous drug release through diffusion upon contact with the ocular surface. Finite element analysis is utilized to study the intraocular drug transport dynamics of glaucoma and optimize the overall layout of the device. Microstructural units undergo deformation under loading, altering the interstitial spaces and modulating the drug release rate. This device can adaptively adjust its drug release rate based on changes in intraocular pressure (IOP) and can be proactively regulated in response to cyclic eye loads, accommodating elevated IOP caused by varying body postures and activities. As a flexible, non-invasive, highly dynamic, and adaptive drug delivery platform, it holds significant potential for future biomedical applications.

In silico evaluation of corneal patch eluting anti-VEGF agents concept

This study introduces a novel approach utilizing a temporary drug-eluting hydrogel corneal patch to prevent neovascularization, alongside a numerical predictive tool for assessing the release and transport kinetics of bevacizumab (BVZ) after the keratoplasty. A key focus was investigating the impact of tear film clearance on the release kinetics and drug transport from the designed corneal patch. The proposed tear drug clearance model incorporates the physiological mechanism of lacrimal flow (tear turnover), distinguishing itself from previous models. Validation against experimental data confirms the model's robustness, despite limitations such as a 2D axisymmetrical framework and omission of blink frequency and saccadic eye movements potential effects. Analysis highlights the significant influence of lacrimal flow on ocular drug transport, with the corneal patch extending BVZ residence time compared to topical administration. This research sets the stage for exploring multi-layer drug-eluting corneal patches as a promising therapeutic strategy in ocular health.

How can machine learning and multiscale modeling benefit ocular drug development?

The eyes possess sophisticated physiological structures, diverse disease targets, limited drug delivery space, distinctive barriers, and complicated biomechanical processes, requiring a more in-depth understanding of the interactions between drug delivery systems and biological systems for ocular formulation development. However, the tiny size of the eyes makes sampling difficult and invasive studies costly and ethically constrained. Developing ocular formulations following conventional trial-and-error formulation and manufacturing process screening procedures is inefficient. Along with the popularity of computational pharmaceutics, non-invasive in silico modeling & simulation offer new opportunities for the paradigm shift of ocular formulation development. The current work first systematically reviews the theoretical underpinnings, advanced applications, and unique advantages of data-driven machine learning and multiscale simulation approaches represented by molecular simulation, mathematical modeling, and pharmacokinetic (PK)/pharmacodynamic (PD) modeling for ocular drug development. Following this, a new computer-driven framework for rational pharmaceutical formulation design is proposed, inspired by the potential of in silico explorations in understanding drug delivery details and facilitating drug formulation design. Lastly, to promote the paradigm shift, integrated in silico methodologies were highlighted, and discussions on data challenges, model practicality, personalized modeling, regulatory science, interdisciplinary collaboration, and talent training were conducted in detail with a view to achieving more efficient objective-oriented pharmaceutical formulation design.

A GPU accelerated study of aqueous humor dynamics in human eyes using the lattice Boltzmann method

In this paper, we presented a 3D human eyes aqueous humor (AH) dynamics model, and additionally, designed and optimized it using GPU technology. First, the feasibility of the model is demonstrated through validation. Then, the effect of different factors on AH flow was investigated using the validated model. The experimental results showed that AH flow more rapidly when standing than supine; the intraocular temperature has the greatest effect on AH flow compared to other factors; the AH secretion rate and trabecular meshwork (TM) permeability had a greater effect on intraocular pressure (IOP). Corneal indentation and ovoid anterior chamber (AC) can also affect AH flow. Finally, the PartSparse algorithm based GPU can save more than 50% of the memory consumption and achieves a performance of 1491.29 MLUPS and a Speedup of 837.61 times.

Ocular Fluid Mechanics and Drug Delivery: A Review of Mathematical and Computational Models

The human eye is a complex biomechanical structure with a range of biomechanical processes involved in various physiological as well as pathological conditions. Fluid flow inside different domains of the eye is one of the most significant biomechanical processes that tend to perform a wide variety of functions and when combined with other biophysical processes play a crucial role in ocular drug delivery. However, it is quite difficult to comprehend the effect of these processes on drug transport and associated treatment experimentally because of ethical constraints and economic feasibility. Computational modeling on the other hand is an excellent means to understand the associated complexity between these aforementioned processes and drug delivery. A wide range of computational models specific to different types of fluids present in different domains of the eye as well as varying drug delivery modes has been established to understand the fluid flow behavior and drug transport phenomenon in an insilico manner. These computational models have been used as a non-invasive tool to aid ophthalmologists in identifying the challenges associated with a particular drug delivery mode while treating particular eye diseases and to advance the understanding of the biomechanical behavior of the eye. In this regard, the author attempts to summarize the existing computational and mathematical approaches proposed in the last two decades for understanding the fluid mechanics and drug transport associated with different domains of the eye, together with their application to modify the existing treatment processes.

Effect of aging on heat transfer, fluid flow and drug transport in anterior human eye: A computational study

There are a lot of geometrical and morphological changes that happen in the human eye with age. Primary open-angle glaucoma, which is caused by the increase in intraocular pressure inside the anterior chamber of the eye is also associated with the physiological aging of the eye. Therefore, it is crucial to understand the effects of aging on drug delivery in the human eye when applied topically. Consequently, a numerical model of topical drug delivery for an aging human eye has been developed using commercial software COMSOL Multiphysics in the current study. Three different age groups (young, middle and old) have been considered and the changes in geometrical and tissue properties of different domains of the eye with age have been included in the numerical model. The effect of aging on heat transfer, aqueous humor flow, intraocular pressure and drug concentration in different domains and orientations of the eye have been investigated. Additionally, an attempt has been made to predict the best class of anti-glaucomatic treatment in silico that should be preferred to treat primary open-angle glaucoma effectively. Results illustrate that there is a decrease in the average corneal temperature and an increase in the temperature deviation across the cornea with age. Further, there is a decrease in the aqueous humor flow magnitude in the anterior chamber of the eye and an increase in intraocular pressure in the anterior chamber of older age groups, which leads to primary open-angle glaucoma. The reduced aqueous humor flow leads to increased drug concentration in the anterior chamber as well as iris and reduced drug concentration in the trabecular mesh of the older age groups, thereby affecting the treatment efficacy. Additionally, our simulated results demonstrate that anti-glaucomatic treatments should be more focused on treating the trabecular mesh rather than the ciliary body of the eye.

Numerical modeling of therapeutic lens drug delivery in the anterior human eye for the treatment of primary open-angle glaucoma

A numerical model of drug delivery from a therapeutic lens in the anterior portion of the human eye has been developed for a more effective treatment plan of primary open-angle glaucoma. The numerical model takes into account the drug diffusion through the therapeutic lens along with heat transfer and aqueous humor flow in different orientations of the human eye (supine (two-dimensional) as well as standing (three-dimensional)). Results illustrate that the drug diffuses through the therapeutic lens to the cornea and is convected into the anterior chamber of the eye due to the temperature gradient across the eye. In addition, eye orientation significantly affects drug delivery with supine orientation providing better and uniform drug exposure in different target regions of the eye as compared to standing in the case of the therapeutic lens. Furthermore, a comparison of the therapeutic efficacy of the therapeutic lens has been done with topical administration and the drug uptake results from both the drug delivery modes have been validated with the experimental data reported in the literature. The developed model may help ophthalmologists to comprehend the transport and retention of different drugs in different domains and orientations of the human eye when administered through a therapeutic lens.

Computer modeling of drug delivery in the anterior human eye after subconjunctival and episcleral implantation

Recently, subconjunctival and episcleral implants have been proposed in the treatment of anterior eye diseases. In order to improve the delivery efficacy, it is important to understand the transport process of the implanted drugs. A 3D computational model, which includes heat transfer, aqueous humor (AH) flow, as well as diffusive and convective transport of the drug concentration, is developed to study the temporal and spatial evolution of the drug in the anterior segment of a human eye after subconjunctival and episcleral implantation, with a focus on drug delivery to three targets: iris, lens, and trabecular meshwork (TM). The release rate of the implanted drug is based on experimental data and effects of implantation location, eye orientation, and AH flow are investigated. Our numerical results indicate that subconjunctival implantation is more effective than episcleral implantation for drug delivery to all the three targets, and the accumulative amount of drug delivered to the three targets is larger in the horizontally-facing eye than in the up-facing eye. Implantation at the 12 o'clock circumferential position is the most effective for drug delivery to iris and lens, and the 3 o'clock position is the most effective for drug delivery to TM. This study may help to better understand the delivery process of implanted drugs in the anterior human eye, and improve delivery efficacy for clinical treatment of anterior eye diseases.