Corneal Biomechanical Properties in High Myopia Measured by Dynamic Scheimpflug Imaging Technology.

Abstract

The cornea is a viscoelastic tissue with viscous and elastic properties. The information of corneal biomechanical changes in high myopia has implications for understanding the pathogenesis of high myopia and primary open angle glaucoma. However, the knowledge of corneal biomechanics in high myopia is limited. To compare the corneal biomechanical properties in high-myopia subjects and emmetropia subjects. Dynamic Scheimpflug imaging technology was used to measure intraocular pressure, central corneal thickness, and corneal biomechanical parameters, including time at the first applanation, velocity at the first applanation, length at the first applanation, deformation amplitude at the first applanation, time at the second applanation, A2V (velocity at the second applanation), length at the second applanation (A2L), deformation amplitude at the second applanation, time at the highest concavity, radius curvature at the highest concavity (HCR), maximal deformation amplitude (MDA), and peak distance. This study included 40 subjects with high myopia and 61 emmetropia subjects. The high-myopia demonstrated greater MDA compared with the emmetropia (1.07 ± 0.01 vs. 1.02 ± 0.01 mm; P < .001) after adjusting for age and intraocular pressure. Pooling analysis found that the high myopia exhibited a smaller HCR, greater MDA, faster A2V and shorter A2L, with a pooled mean difference of -0.21 mm (95% confidential interval [95% CI], -0.30 to -0.13; P < .001) for HCR, 0.05 mm (95% CI, 0.04 to 0.06; P < .001) for MDA, -0.03 m/s (95% CI, -0.06 to -0.002; P = .034) for A2V, and -0.05 mm (95% CI, -0.08 to -0.02; P = .001) for A2L. Eyes with high myopia showed a significantly smaller HCR, greater MDA, faster A2V, and shorter A2L than did those with emmetropia, which indicated that the cornea in an eye with high myopia becomes weaker and more deformable.