Hans W. Liepmann Professor of Aeronautics and Medical Engineering California Institute of Technology, United States
Introduction:: Age-related macular degeneration (AMD) is the leading cause of central vision loss in the developed world. Researchers estimate that 288 million people will suffer from AMD by 2040. Wet AMD can usually be managed through serial intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents. However, the treatment's effectiveness is varied. The half-life of anti-VEGF agents is limited, and the drug delivery mechanism in the eye is not well understood.
This study investigates how thermally induced fluid mixing accelerates drug transport in a model eye. This research extends previous work that utilized two-dimensional planar particle image velocimetry (PIV) to three-dimensional PIV on an eye model. The setup captures circulation across the eye model and enables a deeper understanding of heat addition's potential to improve drug delivery and treatment effectiveness.
Materials and Methods:: We have created a 24.5 mm glass eye model. To achieve a physiologically accurate viscosity, we use 54.5% NaI solution by weight. This solution also matches the index of refraction of pyrex glass, thereby reducing the imaging distortion. The heat source is composed of a thermal pad and a Peltier heather (TEC1-12706), which allows for both heating and cooling. Silver-coated nanospheres are used for tracer particles, and a blue laser is used to illuminate the particles throughout the eye model. Three high-speed cameras angled at the model capture 6000 photos each over the course of 10 minutes of heating, allowing for data collection and flow visualization.
Results, Conclusions, and Discussions:: We performed three-dimensional particle image velocimetry calculations using TSI’s V3V software. Particle movements were measured between frames, and the resulting velocity was calculated. Within 10 minutes of ΔT=10° heating, circulation was induced in the eye model.
This study demonstrated that heat can increase fluid mixing in an in-vitro eye model. This finding sheds light on thermally induced convection’s potential to improving drug delivery for age-related macular degeneration. Future works may include using a more complex, physiologically accurate eye model, which will allow for a fuller picture of circulation.
Acknowledgements (Optional): : This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301.
References (Optional): : Huang, J., Gharib, M. Ann Biomed Eng, 2021, Vol 49, pp. 251–261
