A front-tracking study of retinal detachment treatment by magnetic drop targeting

TL;DR

This study models and analyzes a novel magnetic ferrofluid drop targeting method for retinal detachment treatment, considering realistic eye geometry and rheology, to optimize device parameters and improve treatment efficacy.

Contribution

It introduces a comprehensive 3D front-tracking simulation approach for ferrofluid drop targeting in retinal detachment, incorporating realistic eye geometry and rheological effects.

Findings

Magnetic permeability ratio significantly affects drop shape and coverage.

Increasing magnetic Bond number enhances coverage and force but raises stress.

Reducing surface tension mitigates retinal stress concentration.

Abstract

We investigate the Ferrofluid Drop Targeting (FDT) for the treatment of the Retinal Detachment (RD), considering, for the first time, the real 3D geometry of an eye and magnets configurations as well as the viscoelastic rheology of the medium, i.e., the Vitreous Humor (VH). A Front-Tracking Method (FTM) is extended to handle a general 3D unstructured Eulerian grid and strong wall effects. The challenges include the accuracy and robustness of the solver when the drop spreads on the retina under the effect of a magnetic field, which necessitates the design of a multi-region Eulerian grid and defining a threshold distance between the front and wall, along with the choice of an effective front smoothing and volume correction FTM sub-algorithms near the walls. After model validations, the effect of different design parameters on important objectives, such as the travel time, settling time, retinal coverage area, and impact compressive stress, are studied. The results reveal that, in addition to the magnetic Bond number, the ratio of the drop-to-VH magnetic permeabilities plays a key role in the terminal shape parameters, like the retinal coverage. Additionally, simultaneously increasing these two parameters, significantly increase the total FDT force, coverage area, and stress concentration, while decreasing the drop-VH surface tension can mitigate the stress concentration on the retina.