A Computational Fluid Dynamic Study on the Relief of Intraocular Pressure in the Human Eye in Glaucoma Surgery

Abstract

This study investigates the immediate post-operative outcomes of glaucoma filtration surgeries using computational fluid dynamics (CFD). Three surgical procedures, namely trabeculectomy, non penetrating deep sclerectomy (NPDS), and modified NPDS (mNPDS) were simulated across 3D eye models to evaluate intraocular pressure (IOP) reduction and flow dynamics. Results were analysed for both unsutured conditions, where surgical incisions were open to atmosphere, and sutured conditions, where flow resistance was introduced. Key parameters such as velocity patterns, recirculation zones, and wall shear stress (WSS) were compared to clinical and experimental studies. Initial simulations were performed on an idealised eye geometry, demonstrating that CFD effectively replicated clinical trends in IOP reduction and surgical outcomes. Trabeculectomy and mNPDS were shown to achieve appropriate post-operative IOP levels, with mNPDS more closely aligning with physiologically balanced aqueous humour flow. NPDS was less effective, highlighting its sensitivity to surgical techniques. While the use of an idealised model provided valuable insights, it limited the study's ability to capture anatomical variability. To address this limitation, ethnic-representative models were developed for European and African eyes based on biometric data. These models revealed differences in flow dynamics, influenced by variations in anterior chamber parameters. The African eye models exhibited lower velocities near the corneal wall, indicating potential nutrient deficiencies. These findings emphasize the importance of ethnicity specific anatomy in surgical planning, particularly as glaucoma tends to present earlier in African populations, when anterior chamber depths (ACDs) are typically larger. Conversely, the European eye models demonstrated more balanced flow patterns, aligning more closely with normal flow conditions. Despite its promising results, the study acknowledges the limitations in the accuracy of biometry data, particularly due to variability in measurement techniques and the influence of factors like age and surgical timing. These variables may cause discrepancies between simulated and clinical outcomes, particularly as anterior chamber parameters change significantly over a patient’s lifetime. Additionally, while the models relied on ethnic averages, real-world geometries exhibit greater variability, underscoring the need for patient-specific approaches to glaucoma surgery. This study is the first to compare glaucoma surgical treatments using CFD and the first to incorporate ethnic-representative anterior chamber models. The findings highlight CFD's potential as a virtual tool for evaluating surgical techniques, offering a cost-effective and time-efficient method for assessing outcomes prior to clinical trials. Future work should focus on refining patient-specific geometries, integrating finite element models for tissue biomechanics, and validating CFD results with clinical data. By improving our understanding of how surgical interventions influence aqueous humour dynamics, this study lays the groundwork for optimizing glaucoma treatments and improving long-term patient outcomes.