Yuting Tong, Yuehua Zhou, Yuqin Du, Yu Li

Ineye Hospital of Chengdu University of Traditional Chinese Medicine (TCM), Chengdu 610036, China

Objective: To observe the changes in retinal peripheral defocus and corneal higher-order aberrations in patients with myopic anisometropia before and after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and to explore the correlations between retinal peripheral defocus and corneal higherorder aberrations.

Methods: This was a prospective clinical study. Totally 60 patients (120 eyes) with myopic anisometropia who came to the Ineye Hospital of Chengdu University of TCM for FS-LASIK from September to December 2023 were included in this study. The eyes of the patients with myopic anisometropia were divided into two groups according to the equivalent spherical refraction: the high myopia group (60 eyes) and the low myopia group (60 eyes). Retinal peripheral defocus was measured by Multispectral refraction topography before and 3 months after FS-LASIK.According to the measurement range, the retinal peripheral defocus was divided into total peripheral retinal defocus (TRDV), the average peripheral retinal defocus of 0° to 10°, 10° to 20°, 20° to 30°, 30° to 40° and 40° to 53° (RDV0-10, RDV10-20, RDV20-30, RDV30-40 and RDV40-53). Corneal higher-order aberrations were measured by Itrace analyzer including the total higher-order aberration (tHOA), the vertical trefoil, the vertical coma, the horizontal coma, the horizontal trefoil, and the spherical aberration (SA). The differences of retinal peripheral defocus between groups were analyzed by paired sample t-test and the differences of corneal higher-order aberrations between groups were analyzed by Wilcoxon rank sum test. Spearman's rank correlation test was used to analyze the correlation between the changes of retinal peripheral defocus and the changes of corneal higher-order aberration parameters before and after FS-LASIK.

Results:  The preoperative TRDV, RDV20-30, RDV30-40, and RDV40-53 in the high myopia group were significantly higher than those in the low myopia group (t=2.82-5.41, all P<0.05). However, all postoperative parameters between the high myopia group and the low myopia group were not significantly different (all P>0.05). In low myopia group, postoperatetive TRDV, RDV20-30, RDV30-40 and RDV40-53 were lower than preoperative (t=2.92-9.96, all P<0.05). In high myopia group, postoperatetive TRDV, RDV10-20, RDV20-30, RDV30-40 and RDV40-53 were lower than preoperative (t=2.66-16.48, all P<0.05). Furthermore, no significant difference was found in preoperative high-order aberration between the high myopia group and the low myopia group (all P>0.05). Notably, both postoperative vertical coma and SA showed significantly higher in the high myopia group than those in the low myopia group (Z=-3.33, P=0.001; Z=-3.70, P<0.001). In both low myopia group and high myopia group, postoperatetive tHOA, the vertical trefoil, the vertical coma, the horizontal coma, the horizontal trefoil, and SA were all higher than preoperative (Z=-5.86--2.66, all P<0.05). In correlation analysis, ΔtHOA was negatively correlated with ΔRDV30-40 and ΔRDV40-53 (r=-0.18, P=0.005; r=-0.18, P=0.004), while Δvertical coma was negatively correlated with ΔTRDV and ΔRDV40-53 (r=-0.15, P=0.020; r=-0.13, P=0.039), Δhorizontal coma was negatively correlated with ΔRDV30-40 and ΔRDV40-53 (r=-0.12, P=0.046; r=-0.13, P=0.039), and Δspherical aberration was negatively correlated with ΔTRDV, ΔRDV30-40, and ΔRDV40-53 (r=-0.13, P=0.033; r=-0.16, P=0.012; r=-0.21, P=0.001). Additionally, Δvertical trefoil and Δhorizontal trefoil were not correlated with the change of retinal peripheral defocus (all P>0.05).

Conclusions: Myopic anisometropia patients had more corneal higher-order aberrations and less retinal peripheral hyperopic defocus after FS-LASIK. Furthermore, the variation of retinal peripheral defocus before and after FS-LASIK was correlated with ΔtHOA, Δcoma, and ΔSA.