Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

Abstract

Background: To investigate the biomechanical properties of the cornea in myopic eyes using corneal visualization Scheimpflug technology (Corvis ST). The relationships between the biomechanical properties of the cornea and the degree of myopia were also investigated. Methods: 265 eyes of 265 subjects were included. Based on spherical equivalent (SE) in diopters (D), participants were divided into four groups: low myopia/control (SE: − 0.50 to − 3.00D), moderate myopia (SE: − 3.00 to − 6.00D), high myopia (SE: − 6.00 to − 10.00D) and severe myopia (SE greater than − 10.00D). Axial length (AL), anterior segment parameters, and corneal biomechanical properties were obtained with the Lenstar LS900, Pentacam HR and Corvis ST, respectively. Results: Mean (±SD) SE was − 7.29 ± 4.31D (range: − 0.63 to − 25.75D). Mean AL was 26.31 ± 1.82 mm (range: 21.87 to 31.94 mm). Significant differences were detected within the four groups in terms of six corneal biomechanical parameters: deformation amplitude (DA), time from start until second applanation (A2-time), length of flattened cornea at the second applanation (A2-length), corneal velocity during the first and second applanation (A2-velocity), time from start to highest concavity (HC-time), and central curvature at highest concavity (HC radius). AL was positively associated with DA whereas negatively associated with A1-velocity and A2-length. SE was positively associated with A2-time, HC-time and A2-velocity, whereas negatively associated with DA. IOP was positively associated with four corneal biomechanical parameters and negatively associated with three parameters. Conclusions: Eyes with severe myopia showed greater DA, lesser A2 time, HC time, and faster A2-velocity compared to low to high myopia. This suggests the cornea becomes weaker and more deformable with elongation of axial length with corresponding increases in myopia. DA, A2-time and A2-velocity could be useful corneal biomechanical indicators in patients with myopia.

Comparison of corneal biomechanics among primary open-angle glaucoma with normal tension or hypertension and controls

“…Consistent with our results, Matalia et al [22] also showed that corneal deformation parameters were unaffected by myopia. However, some other studies [23,24] found that the cornea became more deformable with elongation of the AL with corresponding increases in myopia. The effect of age and AL with DCRs needs to be further verified.…”

The Effect of Axial Length Elongation on Corneal Biomechanical Property

“…This may cause excessive stretching of the retina, choroid, and sclera, which in turn result in a series of eye complications such as macular degeneration, retinal detachment, and posterior staphyloma ( Ohno-Matsui and Jonas, 2019 ). In recent years, researchers have investigated the relationship between corneal biomechanics and axial elongation, and have arrived at various conclusions ( Hon et al, 2017 ; Matalia et al, 2017 ; Long et al, 2019 ; Tubtimthong et al, 2020 ; Yu et al, 2020 ). Long et al believed that spherical equivalent refraction was significantly positively correlated with the stiffness parameter at the first applanation (SP-A1) ( Long et al, 2019 ).…”

“…Previous studies found that high myopia can cause corneal biomechanical changes ( Moshirfar et al, 2019 ). Some studies found a negative correlation between corneal biomechanics and AL ( Long et al, 2019 ; Tubtimthong et al, 2020 ; Yu et al, 2020 ) and suggested that measuring corneal biomechanics can predict axial elongation ( Haseltine et al, 2012 ; Zadnik et al, 2015 ; Long et al, 2019 ; Wu et al, 2019 ). In contrast, other studies suggested that corneal biomechanics is independent of the severity of refractive error ( Lim et al, 2008 ; Inceoglu et al, 2018 ).…”

“…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 ). 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 ).…”

Association of Iris Structural Measurements with Corneal Biomechanics in Myopic Eyes

“…The development of myopia is believed to be induced by various patterns of ocular expansions, including equatorial expansion [5], axial expansion [6], and posterior pole expansion [7]. Accompanied by these expansions, the pathogene-sis of myopia includes the biomechanical alternations of the eyeball outer wall, including the cornea, scleral, lamina cribrosa, and peripapillary ring [8,9]. The corneal stiffness was reported to be reduced with the increase in the myopic degree from Corneal Visualization Scheimpflug Technology (Corvis ST, Oculus, Wetzlar, Germany) studies [10][11][12].…”