[Abstract]：Corvis ST is currently the most commonly used clinical device for assessing living corneal biomechanics. The new parameter SSI has been a hot topic of clinical research in recent years, which not only directly can provide corneal biomaterial stiffness, but also closely correlates with the progression of certain diseases. The new parameter SSI was generated based on predictions of corneal behaviour using finite element (FE) numerical modelling to simulate the effects of IOP and Corvis ST jets. The SSI algorithm does not change with changes in CCT, IOP, or BIOP. But IT is clearly associated with altered collagen fibres in the corneosclera. The principles of SSI, the relationship between age and SSI, the relationship between eye axis and SSI, the relationship between myopia level and SSI, and the application of SSI are summarised and concluded.