Evaluation of flow field in the anterior segment during irrigation and aspiration in cataract surgery with three-dimensional computational simulation.

INTRODUCTION:To quantitatively analyze the flow field and fluid pressure contour in the anterior segment during the irrigation and aspiration (I/A) procedure by means of computational fluid dynamics (CFD) simulation. METHODS:Four different models were established combining the irrigation sleeve, aspiration cannula, anterior chamber, and capsule to simulate various scenarios during the coaxial I/A procedure. Commercial CFX software was applied to perform the steady-state simulation with the k-ε turbulence model. The inlet boundary condition was a balanced salt solution with a 100 cm height of pressure, and the mass flow rate boundary condition set at 40 cc/min was applied at the outlet. RESULTS:The four models included the I/A tip located in the middle of the pupillary plane, the capsule equator, and the middle of the posterior capsule. The inlet/outlet pressure at the tip of the I/A cannula was almost the same in the four models. Following ejection into the anterior chamber and capsule bag, the streamline speed rapidly decreased. The pressure in the anterior chamber and capsule bag was approximately 60-70 mmHg. The area on the cornea and capsule closer to the initial streamline of the inlet irrigation possessed larger pressure. The differential pressure on the cornea and capsule was greater when the irrigation orifice directly facing the wall. CONCLUSION:The pressure varies at different positions in the anterior segment during the I/A procedure. The study suggests that specific precautions are required when the tip moves closer to the wall and the irrigation orifice is directed toward the opposite wall.