High-order aberration changes after femtosecond LASIK surgery in patients with high myopia

To investigate the relationship between high-order aberration (HOA) changes and RCST/CT (residual corneal stroma thickness/corneal thickness) after femtosecond LASIK surgery.

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.

Horizontal coma (Z31), spherical aberration (Z40), second horizontal coma (Z51), second horizontal trefoil (Z53), pentafoil (Z55), second spherical aberration (Z60), 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 (Z33; P>0.05). Furthermore, Z31, Z40, 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 Z60 at 1 week and 1 month after surgery (r=0.291 and 0.337, respectively; P<0.05). Ablation depth was positively correlated with Z40 and Z60 at 3 months after surgery (r=0.439 and 0.336, respectively; P<0.05). The RCST/CT was negatively correlated with Z40, Z60, 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.

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.