The aqueous humour dynamics in primary angle closure disease: a computational study.

Purpose: To create a computational fluid dynamics (CFD) model of ocular anterior segment for primary angle closure diseases (PACD) and assess the aqueous humour (AH) dynamics in different angle closure ranges (ACRs).

Methods: The ocular anterior segment geometry was obtained from an optical coherence tomography image by SOLIDWORKS. Three different angle opening distance at 750 µm from the scleral spur (AOD750) values were established to mimic three widths of anterior chamber angle. The AH dynamics were modelled using the Navier-Stokes equation. The 3D CFD model of the ocular anterior segment was created in COMSOL Multiphysics. The major outcome was the maximum flow velocity (MFV) and pressure in the ocular anterior segment. An in vitro simulation model was used to validate the computational results of the pressure and ACRs.

Results: The MFV and pressure both showed a non-linear association with ACR in the CFD models of PACD. The MFV and pressure started to elevate when ACR was larger than 180°, and increased dramatically when the ACR was larger than 270°. The in vitro experiment of the pressure changes was consistent with the CFD model. No significant differences of the MFV and pressure among the three AOD750 models.

Conclusions: The association among the ACR, MFV and pressure is an ascending curve in PACD, and ACR of 180° and 270° are two critical turning points. Our results are consistent with clinical phenomenon and may be used to provide better guidances for the clinical management of PACD in different stages.