Evaluation of Corneal Biomechanical Properties in High Myopia Using the Corivs ST and Its Correlation Factors

Abstract

Objective: To evaluate the corneal biomechanical properties in high myopia using corneal visualization Scheimpflug technology (Corvis ST) and the correlation between corneal biomechanical parameters and intraocular pressure (IOP), axial length (AL), central corneal thickness (CCT), age, and retinal nerve fiber layer thickness. Methods: This was a cross-sectional study. From June to October 2017, 53 patients with high myopia were recruited from Eye Hospital, Wenzhou Medical University. The right eyes of all patients were tested. There were 17 males and 36 females, with a mean age of 33.0±9.6 years (range 18-53 years). Corvis ST was used to obtain the corneal biomechanical parameters, including velocity at the first applanation (A1V), length at the first applanation (A1L), velocity at the second applanation (A2V), length at the second applanation (A2L), deformation amplitude at the highest concavity (DA), radius at the highest concavity (HCR), and peak distance at the highest concavity (PD). The differences in corneal biomechanical parameters were compared between high myopia (-6 D to -10 D, 23 eyes) and extremely high myopia (≤-10 D, 30 eyes). Data were analyzed using independent t test and Pearson correlation. Results: There was a significant difference in A2L (t=1.95, P=0.043) between the high myopia group and extremely high myopia group. There was a negative correlation between IOP and A1V, PD, DA (r=-0.56, -0.46, -0.63, P<0.001) and a positive correlation between IOP and A2V (r=0.37, P=0.005). There was a positive correlation between PD and AL (r=0.43, P=0.001). A1L, A2L, A2V were positively correlated with CCT (r=0.33, P=0.043; r=0.28, P=0.041; r=0.39, P=0.003). PD was negatively correlated with inferior RNFL thickness (r=-0.45, P=0.001). All parameters had no significant correlation with age. Conclusions: Corneal biomechanical parameters in high myopia are positively correlated with AL and CCT, and negatively correlated with IOP and RNFL thickness, suggesting that cornea of high myopia deformed easily, and the inferior RNFL is easily affected. Key words: axial length; high myopia; corneal biomechanics