Li Kai, Zhang Chuan-Wei, Hong De-Jian, Wu Jing, Yao Yi-Shuo
Department of Ophthalmology, Affiliated Hospital of Nanjing University of Chinese Medicine,Nanjing, 155 Hanzhong Road, Nanjing, 210029, Jiangsu, China.
BMC Ophthalmol. 2019 May 10;19(1):107. doi: 10.1186/s12886-019-1115-0.
Femtosecond laser-assisted LASIK (FS-LASIK) can make ultra-thin corneal flap accurately. MEL 90 excimer laser provides Triple-A ablation mode, which significantly reduces the amount of corneal tissue cutting. This study aimed to investigate the visual and refractive outcomes in patients with high myopia after thin-flap FS-LASIK using the 500 Hz pulse rate of the Triple-A profile.
This prospective study included 90 eyes from 90 patients received thin-flap FS-LASIK using the 500 Hz pulse rate of the Triple-A profile. According to the pre-operative spherical equivalence (SE), the treated eyes were divided into two groups: the first group (ranged from - 9.0D to - 6.0D) and the second group (ranged from - 11.15D to - 9.0 D). The parameters evaluated pre-operatively and 6 month post-operatively included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), SE, efficacy and safety index, posterior central elevation, and corneal higher-order aberrations (HOAs).
The efficacy indexes were 1.149 ± 0.150 for the first group and 1.173 ± 0.136 for the second group (P > 0.05), whereas safety indexes were 1.135 ± 0.154 and 1.158 ± 0.137 (P > 0.05) respectively. Moreover, 93.8 and 90.6% of patients had an UDVA of 20/20, 51.2 and 49.8% had a UDVA of 20/16 for the first and second groups, respectively; yet, there were no significant differences between both groups at the 20/20 and the 20/16 levels (P > 0.05). 84 and 100% of the firse group patients had a SE within ±0.5 D and ± 1.0 D, and 82 and 100% of the second group patients. There was no significant myopia regression in both groups after 6 months follow-up. At 1, 3 and 6-month after surgery, there were no significant differences in the posterior central elevation between the two groups (P > 0.05). The induction of total HOAs, spherical aberration, and horizontal coma in the first group were significantly less than that in the second group at the 6- month follow-up (P < 0.05), while the differences of the RMS value of vertical coma between both groups were not significant (P > 0.05). The ablation was significantly associated with the post-operative increase in total HOAs, spherical aberration and horizontal coma (P < 0.05),but not with vertical coma (P > 0.05).
Our results indicate that using the Triple-A ablation profile of the MEL 90 excimer laser associated with thin-flap is a safe, efficient, and predictable method to correct SE up to - 11.15D. However, for patients with high myopia, under the premise of ensuring a certain optical zone diameter, the ablation depth should be minimized to reduce the increase of the post-operative HOAs so as to improve the visual quality.
飞秒激光制瓣准分子原位角膜磨镶术（FS-LASIK）能精确制作超薄角膜瓣。MEL 90准分子激光提供了三重-A消融模式，显著减少了角膜组织切削量。本研究旨在探讨采用三重-A模式500Hz脉冲频率的薄瓣FS-LASIK治疗高度近视患者的视觉和屈光效果。
本前瞻性研究纳入90例患者的90只眼，均接受采用三重-A模式500Hz脉冲频率的薄瓣FS-LASIK治疗。根据术前等效球镜度（SE），将患眼分为两组：第一组（-9.0D至-6.0D）和第二组（-11.15D至-9.0D）。术前及术后6个月评估的参数包括裸眼远视力（UDVA）、矫正远视力（CDVA）、SE、有效性和安全性指数、中央后表面高度以及角膜高阶像差（HOAs）。
第一组的有效性指数为1.149±0.150，第二组为1.173±0.136（P>0.05）；安全性指数分别为1.135±0.154和1.158±0.137（P>0.05）。此外，第一组和第二组分别有93.8%和90.6%的患者UDVA达到20/20，51.2%和49.8%的患者UDVA达到20/16；然而，两组在20/20和20/16水平上无显著差异（P>0.05）。第一组和第二组分别有84%和100%的患者SE在±0.5D和±1.0D范围内。随访6个月后，两组均无明显的近视回退。术后1、3和6个月，两组中央后表面高度无显著差异（P>0.05）。随访6个月时，第一组总HOAs、球差和水平彗差的诱导量显著低于第二组（P<0.05），而两组垂直彗差的均方根值差异无统计学意义（P>0.05）。消融与术后总HOAs、球差和水平彗差的增加显著相关（P<0.05），但与垂直彗差无关（P>0.05）。
我们的结果表明，采用与薄瓣相关的MEL 90准分子激光三重-A消融模式是一种安全、有效且可预测的方法，可矫正高达-11.15D的SE。然而，对于高度近视患者，在确保一定光学区直径的前提下，应尽量减少消融深度，以减少术后HOAs的增加，从而提高视觉质量。
