Zhang Jing, Zhou Yue-hua, Wang Ning-li, Li Rui
Ophthalmic Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
Chin Med J (Engl). 2008 Jan 20;121(2):137-42.
Laser in situ keratomileusis (LASIK) has become an efficient and commonly performed procedure to reduce refractive errors. In order to further increase the postoperative visual quality, the wavefront-guided refractive surgery has been a research hotspot in customized surgery. This study was conducted to compare the visual acuity, higher-order aberration, and contrast sensitivity of wavefront-guided LASIK with iris-registration and conventional LASIK.
Two hundred and eleven myopic eyes of 109 patients were enrolled in this prospective study and randomly divided into two groups: the wavefront-guided LASIK (wg LASIK) group (94 eyes) and conventional LASIK group (117 eyes). A Wavescan Wavefront aberrometer was used to analyze Zernike coefficients and the root-mean-square (RMS) of higher order aberrations with 6.0 mm pupil size, and Optec 6500 visual function instrument was used to measure contrast sensitivity (CS) under 5 spatial frequencies before and after surgery in both groups.
The uncorrected visual acuity (UCVA) and the mean spherical equivalent (SE) in wg LASIK group were significantly better than those in conventional LASIK (UCVA, z = 2.339, P = 0.019; SE, t = 2.838, P = 0.005) at 3 months after surgery. Moreover, the increase in Z(3)(-3), Z(3)(1), Z(3)(3), Z(4)(0), Z(5)(-1), Z(5)(1), Z(5)(5) and Z(6)(-6) in wg LASIK group was statistically smaller than that in conventional LASIK group (P < 0.05). In wg LASIK group, eyes with a higher amount of the preoperative RMS of the higher order aberrations (RMSh = 0.30 microm) showed a statistically lower increase (13.5%) than those in conventional LASIK group at 3 months after surgery (33.3%) (P = 0.004). And the values of 4th order spherical aberration (4thSA) and the root mean square of 6th order aberration (RMS6) in wg LASIK group were significantly lower than those in conventional group in eyes which had higher preoperative astigmatism (= 1.0D) (4thSA, P = 0.03; RMS6, P = 0.02). Wg LASIK group showed better CS values than the correspondingly preoperative values at all spatial frequencies with and without glare at 3 months after the surgery while conventional LASIK group displayed reduced CS values except for 1.5 and 3 cycles per degree with glare. The differences between the two groups were statistically significant (P < 0.001).
Wavefront-guided LASIK with iris-registration is efficient to reduce higher order aberrations especially spherical and coma aberrations, and to improve postoperative visual acuity and contrast sensitivity compared with conventional LASIK. The application of wavefront-guided LASIK with iris-registration is particularly suitable for eyes with higher preoperative RMSh values and eyes with higher preoperative astigmatism.
准分子原位角膜磨镶术（LASIK）已成为矫正屈光不正的一种有效且常用的手术方法。为了进一步提高术后视觉质量，波前像差引导的屈光手术已成为个性化手术的研究热点。本研究旨在比较波前像差引导的虹膜定位LASIK与传统LASIK的视力、高阶像差和对比敏感度。
本前瞻性研究纳入了109例患者的211只近视眼，随机分为两组：波前像差引导的LASIK（wg LASIK）组（94只眼）和传统LASIK组（117只眼）。使用Wavescan波前像差仪分析6.0mm瞳孔直径下的泽尼克系数和高阶像差的均方根（RMS），并使用Optec 6500视觉功能仪测量两组患者手术前后5个空间频率下的对比敏感度（CS）。
术后3个月，wg LASIK组的裸眼视力（UCVA）和平均球镜当量（SE）显著优于传统LASIK组（UCVA，z = 2.339，P = 0.019；SE，t = 2.838，P = 0.005）。此外，wg LASIK组Z(3)(-3)、Z(3)(1)、Z(3)(3)、Z(4)(0)、Z(5)(-1)、Z(5)(1)、Z(5)(5)和Z(6)(-6)的增加在统计学上小于传统LASIK组（P < 0.05）。在wg LASIK组中，术前高阶像差RMS较高（RMSh = 0.30μm）的眼睛术后3个月的增加幅度（13.5%）在统计学上低于传统LASIK组（33.3%）（P = 0.004）。在术前散光较高（≥1.0D）的眼睛中，wg LASIK组的四阶球差（4thSA）和六阶像差均方根（RMS6）值显著低于传统组（4thSA，P = 0.03；RMS6，P = 0.02）。术后3个月，在所有空间频率下，无论有无眩光，wg LASIK组的CS值均优于相应的术前值；而传统LASIK组除了在有眩光时1.5和3周/度的空间频率外，CS值均降低。两组之间的差异具有统计学意义（P < 0.001）。
与传统LASIK相比，波前像差引导的虹膜定位LASIK能有效降低高阶像差，尤其是球差和彗差，并提高术后视力和对比敏感度。波前像差引导的虹膜定位LASIK特别适用于术前RMSh值较高的眼睛和术前散光较高的眼睛。
