TO STUDY THE EFFECTS OF INTRASTROMAL CORNEAL RING GEOMETRY AND SURGICAL CONDITIONS ON THE POSTSURGICAL OUTCOMES THROUGH FINITE ELEMENT ANALYSIS

Intrastromal corneal ring (ICR) is a transparent circular implant inserted in the cornea to provide structural support in an attempt to alleviate preexisting refractive errors. This is a surgical procedure whose success depends on control parameters such as, ICR geometry which includes ICR thickness and diameter, and surgical conditions which includes ICR implantation depth and diameter of corneal pocket. This research utilizes finite element (FE) analysis techniques to develop a high fidelity and computationally efficient three-dimensional axisymmetric cornea model to study the relative effects of ICR implant geometry and surgical conditions on the postsurgical shape of the cornea utilizing corneal apical displacement results. The FE analysis results indicate that ICR implantation reduces myopia, and the amount of myopic rectification is dependent on the control parameters which include ICR geometry and surgical conditions. The results show that an increase in ICR thickness leads to an increase in myopic rectification, whereas an increase in ICR radius leads to a decrease in myopic rectification. ICR implantation depth analysis results suggest that corneal depth of 40-75% provides steady myopic rectification. Corneal pocket diameter analysis revealed that smaller corneal pockets lead to increase in myopic rectification. Overall, the FE model results are in qualitative agreement with published clinical studies. Finally, the combined impact of the control parameters on myopic rectification was studied by conducting a sensitivity analysis and an equation relating myopic rectification with control parameters was developed utilizing simple linear regression analysis.