Age distribution and associated factors of cornea biomechanical parameter stress-strain index in Chinese healthy population

Abstract

Background To investigate the new cornea biomechanical parameter stress-strain index (SSI) in Chinese healthy people and the factors associated with SSI. Methods A total of 175 eyes from 175 participants were included in this study. Axial length was measured with the Lenstar LS-900. Pentacam measured curvature of the cornea and anterior chamber volume (ACV). Cornea biomechanical properties assessments were performed by corneal visualization Scheimpflug technology (Corvis ST). Student’s t-test, one-way ANOVA, partial least square linear regression (PLSLR) and linear mixed effects (LME) model were used in the statistical analysis. Results The mean (±SD) SSI was 1.14 ± 0.22 (range, 0.66–1.78) in all subjects and affected by age significantly after age of 35 (P < 0.05). In LME models, SSI was significantly associated with age (β = 0.526, P < 0.001), axial length (AL) (β = − 0.541, P < 0.001), intraocular pressure (IOP) (β = 0.326, P < 0.001) and steepest radius of anterior corneal curvature (RsF) (β = 0.229, P < 0.001) but not with ACV, biomechanical corrected intraocular pressure (bIOP), flattest radius of anterior corneal curvature (RfF) or central corneal thickness (CCT) (P > 0.05 for each). Conclusions SSI increased with age after the age of 35. In addition to age, SSI was positively correlated with RsF and IOP, while negatively correlated with AL.

The Effect of Axial Length Elongation on Corneal Biomechanical Property

“…In concordance with our previous findings, the SSI of the SEE group was significantly lower than that of the MEE group ( Liu et al, 2020 ). In the MEE group, the SSI was significantly negatively correlated with AL.…”

“…Regarding corneal biomechanical measurement technology, the new parameter stress-strain index (SSI) provided by corneal visualization Scheimpflug technology (Corvis ST) can reflect corneal stiffness without being affected by central corneal thickness (CCT) or intraocular pressure (IOP) ( Eliasy et al, 2019 ). One of our previous studies found that the SSI was negatively correlated with AL, but high myopia was not included for that study ( Liu et al, 2020 ). However, the extent of myopia may influence corneal biomechanics ( Yu et al, 2020 ).…”

“…However, the extent of myopia may influence corneal biomechanics ( Yu et al, 2020 ). For example, at the outset, corneal stiffness are weakened as the eye elongates in physiological processes ( Khokhar et al, 2018 ; Han et al, 2020 ; Liu et al, 2020 ). When the elongation enters the pathological stage, corneal stiffness may tend to stabilize ( Larsen, 1971 ; Khokhar et al, 2018 ).…”

Effect of Mydriasis-Caused Intraocular Pressure Changes on Corneal Biomechanical Metrics

“…Previous reports of these relationship were mixed, the DA was correlated with CCT and IOP (Hon and Lam, 2013;Ali et al, 2014;Huseynova et al, 2014), the DARatio2mm had high correlation with CCT and IOP (Vinciguerra et al, 2016), and the IIR correlated with CCT (Vinciguerra et al, 2016) while not with IOP. In other studies, DA, DARatio2mm, IIR, and SP-A1 were all correlated with CCT and IOP (Sedaghat et al, 2020), CBI was correlated with IOP and CCT (Yang et al, 2019), and SSI was correlated with IOP but not with CCT (Liu et al, 2020). The studies noted above were cross-sectional, and the variation range in both subjects and biometric parameters was large, which may have influenced the correlation results.…”

Evaluation of the Relationship Between the Changes in the Corneal Biomechanical Properties and Changes in the Anterior Segment OCT Parameters Following Customized Corneal Cross-Linking

“…SSI is a parameter created for evaluating corneal rigidity that does not depend on bIOP and corneal thickness but depends on age. 26 , 27 The higher the SSI, the higher the corneal rigidity. 28 SSI was calculated using the following formula:…”