Influence of design parameters and capsulorhexis on intraocular lens stabilities: A 3D finite element analysis

Background Current treatment of cataract widely used in clinics is by removal of the opacified content from the lens capsule which is followed by insertion of an artificial intraocular lens (IOL). The IOL needs to remain stabilized in the capsular bag for the eye to achieve desired optical quality. The present study aims to investigate how different design parameters of the IOL can influence the axial and rotational stabilities of IOLs using Finite Element Analysis. Methods Eight designs of IOL with variations in types of optics surface, types of haptics and haptic angulation were constructed using parameters obtained from an online IOL databank (IOLs.eu). Each IOL was subjected to compressional simulations both by two clamps and by a collapsed natural lens capsule with an anterior rhexis. Comparisons were made between the two scenarios on axial displacement, rotation, and distribution of stresses. Results The clamps compression method set out by ISO does not always produce the same outcome as the in-the-bag analysis. The open-loop IOLs show better axial stability while the closed-loop IOLs show better rotational stability when compressed by two clamps. Simulations of IOL in the capsular bag only demonstrate better rotational stability for closed-loop designs. Conclusions The rotational stability of an IOL is largely dependent on its haptic design whilst the axial stability is affected by the appearance of the rhexis to the anterior capsule which has a major influence on designs with a haptic angulation.