Effect of suction angle on zonular fibers during residual cortex removal in phacoemulsification using finite element...

To evaluate the effect of suction direction on zonular fibers' mechanical behavior using finite element modeling.

Laboratory study.

3D finite element model experimental study.

A 3D finite element model was developed, including nucleus covered by cortex and capsule. Similar to cataract surgery, a circular rapture was considered at the top of the capsule to apply suction pressure. Finally, zonular fibers were modeled as a continuum body using 3D solid elements (C3D8R). A custom FORTRAN subroutine was implemented to enforce tension-only behavior, mimicking the physiological characteristics of the zonular fibers, which are resistant to tensile but not compressive loads. This method allows for a realistic simulation of zonular mechanics during cortical aspiration.

The suction processes in tangential and normal angles were simulated. The resulting relative displacements between the cortex and capsule, as a criterion of cortex separation, vs the resulting maximum zonule displacements, were recorded in each model. The cortex-capsule relative displacement vs maximum zonule displacement indicated a diagram slope of 0.09 for tangential applying pressure and 0.02 in the case of applying normal pressure.

The results illustrated that zonular fibers were less tensile in a specific magnitude of cortex-capsule relative displacement under tangential applying pressure, which means that eye zonular fibers have a lower risk of failure until the separation of the lens cortex.