Project Page - Intraocular Pressure Control
Maintaining introaocular pressure stability is critical to surgical effectiveness and safety in intraocular surgery. In cataract lens removal procedure, the continuous fluid irrigation and aspiration creates disturbances in the intraocular pressure, which subsequently causes deformation and damage to intraocular tissues. Incidental surge phenomena, when materials blocking the aspiration pathway are suddenly released, creating sudden pressure drop and cornea collapse. To improve the pressure stability under such severe pressure disturbances, this project presents an add-on irrigation and pressure control system to existing fluid control machine. The effect of the enhanced dynamic response for the closed loop pressure control is demonstrated by reduced corneal deformation in pig eye experiment.
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The illustration of surge phenomenon due to occlusion at the aspiration port.
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Developed add-on fluid system (a) CAD model with the irrigation pump, microcontroller, and power supply. (b) Physical pump system. Note: Labeled number 1 is connected to the fluid control machine and number 2 is connected to the surgical instrument.
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Faster surge recovery with our IOP control. To simulate occlusion at the aspiration port, the aspiration tube was manually squeezed to limit the flow rate until full blockage was created, followed by releasing the tube to suddenly increase aspiration flow rate. This will suddenly decrease the IOP and shallows the anterior chamber, thereby providing a good example for surge experiments. To focus on the effectiveness of surge avoidance and eliminate the transient response, a strong vacuum of 600 mmHg was used and IOP control was turned on before applying the blockage.
In the left figure, there is an transient increase in IOP when the aspiration tube is blocked. The blockage was released at t = 2 s, which can be observed by the spike in pasp and the aspiration was suddenly engaged. The response of our system shows a reduced surge peak and recovery time compared to the one with only intravenous (IV) pole control in existing surgical systems.
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Tissue positions were evaluated with the optical coherence tomograph (OCT) cross-sectional visualization when the lowest IOP occurs, which further showcases that the system can avoid tissue damage and deformation. (a) With only IV pole control. (b) Our system.
Publications
- Dynamic Flow Modulation and Pressure Stabilization, Y.T. Lai, A. Barzelay, and T.C. Tsao, IEEE/ASME Transactions on Mechatronics, 2025 (Accepted).
- Add-On Fluidic Control System for Enhancing Intraocular Pressure Stabilization and Reducing Tissue Deformation, Y.T. Lai, A. Barzelay, and T.C. Tsao, 2024 IEEE International Conference on Advanced Intelligent Mechatronics (AIM), 2024. DOI | PDF