Wang Yan, Zhao Kan-Xing, Rao Feng, Yang Xiao-Yan, Hou Jie, Wang Zhao-Qi
Tianjin Medical University, Tianjin Eye Hospital, Refractive Surgery Center, Tianjin 300020, China.
Zhonghua Yan Ke Za Zhi. 2009 Jul;45(7):580-6.
To investigate the changes of the Modulation Transfer Function (MTF) and its effect on visual and optical quality with or without low and higher order wavefront aberration after conventional and wavefront guild laser in situ keratomileusis.
It was a comparative case series. An aberrometer with Hartmann-shark sensor was used to measure the monochromatic aberration of eyes. One hundred and two cases entered the study; 38 cases were randomized to LASIK and 64 were randomized to WFG-LASIK. MTFs of optical system were calculated at various pupil size (3, 4, 5 and 6 mm) respectively and compared pre and 3 month postoperatively between conventional and wavefront guide ablation with or without higher order aberration.
There was a significant increase in MTF positively compared with preoperative values at all spatial frequency (5-60 cycles per degree, c/d ), P < 0.05. MTF values got more improvement without spherical aberration than without coma aberration after LASIK surgery and there was significant different at a spatial frequency of 5 c/d. Higher MTFs were showed in the WFG-LASIK group although there were no significant difference between conventional LASIK group and WFG-LASIK group. However, there were apparently changed without high order aberration as compared to that with high order aberration at all spatial frequency (5-60 c/d. ) in WFG-LASIK group and higher MTFs were showed in the WFG-LASIK group compared with conventional LASIK group and there were significant different (P < 0.05) by calculation and evaluation.
Spherical aberration have more negative role on visual quality than coma aberration after LASIK surgery. With the optical benefits expected from correcting higher aberration, wavefront guide ablation have shown a great benefit for low and high order aberration but it still leave a small amount of high order aberration and need further investigation. MTF is a sensitive and extensive in demonstrating the optical quality in refractive surgery.
研究传统准分子原位角膜磨镶术（LASIK）和波前像差引导的LASIK术后，有或无低阶及高阶波前像差时调制传递函数（MTF）的变化及其对视觉和光学质量的影响。
这是一个对比病例系列研究。使用带有哈特曼-夏克传感器的像差仪测量眼睛的单色像差。102例患者进入研究；38例随机分配至LASIK组，64例随机分配至波前像差引导的LASIK（WFG-LASIK）组。分别计算不同瞳孔大小（3、4、5和6毫米）时光学系统的MTF，并比较传统消融和波前像差引导消融术前及术后3个月有或无高阶像差时的MTF。
与术前值相比，所有空间频率（每度5 - 60周，c/d）下MTF均有显著正向增加，P < 0.05。LASIK术后无球差时MTF值的改善比无彗差时更多，在空间频率为5 c/d时有显著差异。WFG-LASIK组的MTF更高，尽管传统LASIK组和WFG-LASIK组之间无显著差异。然而，WFG-LASIK组在所有空间频率（5 - 60 c/d）下，与有高阶像差相比，无高阶像差时明显变化，且WFG-LASIK组的MTF高于传统LASIK组，经计算和评估有显著差异（P < 0.05）。
LASIK术后球差对视觉质量的负面影响比彗差更大。由于矫正高阶像差可带来光学益处，波前像差引导消融对低阶和高阶像差均显示出很大益处，但仍会残留少量高阶像差，需要进一步研究。MTF在屈光手术中是一种敏感且广泛用于展示光学质量的指标。
