Background: To investigate the relationship between high-order aberration (HOA) changes and RCST/CT (residual corneal stroma thickness/corneal thickness) after femtosecond LASIK surgery.Methods: A total of 65 eyes from 39 patients with high myopia, who had femtosecond (FS) laser-assisted in situ keratomileusis (LASIK) surgery performed in our hospital, were included in this study. HOA and central corneal thickness were measured preoperatively and at 1 week, 1 month, and 3 months after FS-LASIK by Sirius Scheimpflug-Placido topography. Residual corneal stroma thickness (RCST) and ablation depth were measured during surgery. Results: Horizontal coma (Z 3 1 ), spherical aberration (Z 4 0 ), second horizontal coma (Z 5 1 ), second horizontal trefoil (Z 5 3 ), pentafoil (Z 5 5 ), second spherical aberration (Z 6 0 ), and total HOAs were significantly increased at 1 week, 1 month, and 3 months after surgery compared with the preoperative values (P<0.05), but no significant differences were found in horizontal trefoil (Z 3 3 ; P>0.05). Furthermore, Z 3 1 , Z 4 0 , and HOAs were significantly increased at 3 months post-surgery compared with the values at 1 week post-operation (P<0.05).Positive correlations were found between ablation depth and Z 6 0 at 1 week and 1 month after surgery (r=0.291 and 0.337, respectively; P<0.05). Ablation depth was positively correlated with Z 4 0 and Z 6 0 at 3 months after surgery (r=0.439 and 0.336, respectively; P<0.05). The RCST/CT was negatively correlated with Z 4 0 , Z 6 0 , and HOAs at 3 months after surgery (r=−0.322, −0.412, and −0.321, respectively; P<0.05). There were no significant correlations between Zernike coefficients in terms of high-order aberration, HOAs, and RCST/ CT at 1 week and 1 month post-surgery.Conclusions: Corneal HOAs in high myopia patients increased significantly after FS-LASIK surgery, and this was mainly observed as increases in coma and spherical aberration. The greater the ablation depth, the larger the influence on spherical aberrations. The greater the RCST/CT, the smaller the influence of HOAs on the cornea.

BACKGROUND Myopia and high myopia are global public health concerns. Patients with high myopia account for 0.5%-5.0% of the global population. AIM To examine diopters, axial length (AL), higher-order aberrations, and other ocular parameters in Chinese children with myopia, to analyze the influence of structural parameters associated with myopia on visual quality, and to provide a theoretical basis for the prevention and treatment of childhood myopia and high myopia. METHODS This study included 195 children aged 6–17 years with myopia. The AL was measured with an ultrasonic ophthalmic diagnostic instrument, and the aberrations, corneal curvature (minimum K1, maximum K2, and average Km), central corneal thickness, anterior chamber depth, and anterior chamber angle were measured using a Sirius three-dimensional anterior segment analyzer. Using a standard formula, the corneal radius of curvature R (337.3/Km) and AL/R values were obtained. RESULTS The diopter of high myopia compared with low-middle myopia was correlated with age and AL ( r = -0.336, -0.405, P < 0.001), and AL of high myopia was negatively correlated with K1, K2, and Km ( r = -0.673, -0.661, and -0.680, respectively; P < 0.001), and positively correlated with age and the anterior chamber depth ( r = 0.214 and 0.275, respectively; P < 0.05). AL/R was more closely related to diopter than AL in children with myopia, and 94.4% of children with myopia had an AL/R of > 3.00. CONCLUSION The ocular structural parameters of children change because of different diopters. AL/R is more specific and sensitive than AL in evaluating the refractive status of myopia in children. An AL/R of > 3.00 may be used as a specific index of myopia in children. There are differences in AL/R between high myopia and low-middle myopia, which can be used for the classification of ametropia. The degree of myopia has a certain influence on higher-order aberrations.