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Purpose: This study aimed to investigate the correlation of axial length/corneal radius of curvature ratio with stress–strain index (SSI).Methods: Retrospective analysis was conducted to compare the right eyes of those with high myopia (HM, n = 132; age and 10–48 years) with those without high myopia (NHM, n = 135; age and 7–48 years), where the baseline axial length, corneal radius of curvature ratio, and central corneal thickness were analyzed; the differences in two groups were compared; and the relationship of axial length and axial length/corneal radius of curvature ratio with SSI were explored.Results: Compared with AL < 26mm, SSI significantly decreased when AL ≥ 26 mm (p = 0.001), while there was no correlation with AL in the NHM group (r = -0.14, p = 0.12) or HM group (r = -0.09, p = 0.32). AL/CR was significantly associated with SSI in both the NHM (r = -0.4, p < 0.001) and HM (r = -0.18, p = 0.04) groups. In the NHM group, AL/CR was significantly associated with SSI (unstandardized beta = -0.514, se = 0.109, p < 0.001) with the adjustment of age and gender. Additionally, a significant association of SSI with AL/CR was also found after adjusting for age and gender (unstandardized beta = -0.258, se = 0.096, and p = 0.0082) in the HM group.Conclusion: SSI showed a significant negative correlation with AL/CR in patients without high myopia and in patients with high myopia. However, SSI exhibited no decrease with the worsening of myopia, but it gradually remained stable at a low level. The findings of this study validate, to some extent, the possibility of analyzing the dynamic changes in ocular wall stiffness during the development of myopia by measuring in vivo corneal biomechanical parameters.

Purpose: To assess the longitudinal change in components of astigmatism from age 4 to 7 years and its association with axial length-corneal radius ratio (AL/CR). Methods: Children born between September 2011 and August 2012 in Yuhuatai District of Nanjing were invited to participate in the Nanjing Eye Study for a comprehensive eye examination annually since 2015. The data presented in this paper were obtained in 2016, 2017, and 2019. At each study encounter, noncycloplegic autorefraction and ocular biometric parameters were measured. Changes of total astigmatism (TA), corneal astigmatism (CA), anterior corneal astigmatism (ACA), residual astigmatism (RA), and internal astigmatism (IA) were analyzed in clinical notation (Cyl) and vector notation (J0, J45). Results: Nine hundred fifty-four children (mean ± standard deviation of baseline age: 4.63 ± 0.29 years, 53.7% boys) had complete data and were included in this study. Mean slopes of longitudinal changes in Cyl notation were significantly negative for TA, CA, and ACA, but positive for IA. TA, CA, ACA, and RA of J0 notation had a shift toward increasing with-the-rule (WTR) astigmatism and/or decreasing against-the-rule (ATR) astigmatism. TA of J45 notation showed an increase in astigmatism at axis 135° and/or a decrease in astigmatism at axis 45°, while CA and ACA of J45 notation showed an opposite change. Longitudinal changes in ACA and IA were negatively correlated in J0 notation, but not in J45 notation. Based on compensation factor (CF, defined as the minus ratio of IA and ACA), the compensation proportions for J0 in varying degrees (CF: 0.1–2) in 2016, 2017, and 2019 were 91.3%, 93.5%, and 90.0%, respectively, while these for J45 were 74.9%, 76.5%, and 34.6%, respectively. Higher AL/CR increase was associated with less decrease or more increase in CA and ACA of Cyl notation, and a shift toward increasing WTR and/or decreasing ATR in these of J0 notation. Conclusions: The compensatory role of IA was persistent and prominent from 4 to 7 years old for J0 notation in Chinese young children. The progression of AL/CR was correlated with astigmatism originated from the cornea. [ABSTRACT FROM AUTHOR]

AIM: To analyze the refraction status,ocular biological parameters and the relationship between them in 3-12 years old children.METHODS: Totally 1 138(2 276 eyes)children aged 3-12 years old were enrolled in this study from January 2016 to October 2017. Equivalent spherical degree, axial length, corneal curvature and corneal thickness were measured. RESULTS: The average spherical diopter of 1 138 children is -0.67±2.66D, the average corneal curvature is 43.37±1.72D, and the axial length is 23.65±1.41mm. The average corneal curvature of boys is 42.98±1.86D and that of girls is 43.81±1.42D. The axial length of boys is 23.94 ± 1.36 mm and that of girls is 23.32±1.40mm. The central corneal thickness of boys is 541.83±33.73μm and that of girls is 536.10±31.49μm. The corneal astigmatism of boys was 1.53±0.99D and that of girls is 1.65±1.02D. There is a significant difference between boys and girls. Axial length and central corneal thickness are lower in 3-6 age group than those in other age groups. Equivalent diopter and corneal astigmatism are higher than those in other age groups(PCONCLUSION: The axial length and corneal curvature are the main factors affecting the refraction status in children. With the growth axial length, the curvature of cornea also changes to some extent. AL/CR can predict this change.

Purpose: To investigate the relationship between ocular biometrics (OB) and myopia onset. Methods: OB data from students in 4 grades (aged from 6 to 14 years) in China were collected in a 1.5-year longitudinal study. Refractive error was assessed with cycloplegic autorefraction. Results: At baseline, 934 (56.33%) of the subjects (right eye) had myopia. The mean spherical equivalent (SE) and axial length to corneal radius (AL/CR) were − 2.14 ± 1.49 and 3.14 ± 0.11, respectively, in the subjects with myopia and − 0.09 ± 0.21 and 2.98 ± 0.07, respectively, in the subjects without myopia. The correlation between the SE and AL/CR was r = − 0.823 (P < 0.001). The slopes of the SE changing with the AL/CR (and R-squares) were − 0.28 to − 1.80 (0.01–0.14) in the no myopia group, − 3.40 to − 6.20 (0.20–0.48) in the low myopia group, and − 3.37 to − 11.34 (0.16–0.74) in the moderate and high myopia groups. The baseline AL/CR values in grades 1, 3, and 5 were higher in those who developed myopia within 1.5 years. The odds ratio of the AL/CR to myopia onset in 1.5 years was 1.096 (95% confidence interval (CI): 1.060–1.135). Conclusions: Of the five indicators, the AL/CR showed the best correlation with the SE. The adjoint and linear relationship between the AL/CR and the SE tended to increase with SE progression. When myopia progressed beyond a certain range, the AL/CR was significantly different in those without initial myopia who developed it within 1.5 years compared with those who did not. After adjusting for age, sex, school, and grade, the interpretation capability of the current AL/CR to myopia onset in 1.5 years was limited. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the correlation of axial length/corneal radius of curvature ratio with stress-strain index (SSI). Methods: Retrospective analysis was conducted to compare the right eyes of those with high myopia (HM, n = 132; age and 10-48 years) with those without high myopia (NHM, n = 135; age and 7-48 years), where the baseline axial length, corneal radius of curvature ratio, and central corneal thickness were analyzed; the differences in two groups were compared; and the relationship of axial length and axial length/corneal radius of curvature ratio with SSI were explored. Results: Compared with AL < 26mm, SSI significantly decreased when AL ≥ 26 mm ( p = 0.001), while there was no correlation with AL in the NHM group ( r = -0.14, p = 0.12) or HM group ( r = -0.09, p = 0.32). AL/CR was significantly associated with SSI in both the NHM ( r = -0.4, p < 0.001) and HM ( r = -0.18, p = 0.04) groups. In the NHM group, AL/CR was significantly associated with SSI (unstandardized beta = -0.514, se = 0.109, p < 0.001) with the adjustment of age and gender. Additionally, a significant association of SSI with AL/CR was also found after adjusting for age and gender (unstandardized beta = -0.258, se = 0.096, and p = 0.0082) in the HM group. Conclusion: SSI showed a significant negative correlation with AL/CR in patients without high myopia and in patients with high myopia. However, SSI exhibited no decrease with the worsening of myopia, but it gradually remained stable at a low level. The findings of this study validate, to some extent, the possibility of analyzing the dynamic changes in ocular wall stiffness during the development of myopia by measuring in vivo corneal biomechanical parameters., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chu, Ren, Chen, Cheng, Cheng, Cui, Bi and Wu.)