多焦点准分子激光原位角膜磨镶术治疗老视前近视的对比研究

Comparative study of muitifocal LASIK for the correction of pre-presbyopic myopia

目的探讨多焦点准分子激光原位角膜磨镶术（LASIK）治疗老视前近视的可行性。方法前瞻性对照研究。共32例（64只眼）近视眼患者，平均年龄（38．5±2．7）岁；主视眼行常规LASIK。非主视眼行多焦点LASIK。检测项目：远近视力、屈光度、角膜地形图、眼压、超声角膜厚度、对比敏感度、调节幅度、焦深、波阵面像差等。对计量资料计算均数和标准差，检验水准α为0．05，对数据进行双侧检验。将调节增幅和术后角膜多焦点指数、手术前后球差改变进行相关分析。结果随访6—11个月，平均（7Or3）个月。非主视眼术前近视力为（LogMAR-0．082±0．220），术后6个月为（LogMAR-0．004±0．213），术后较术前提高（t=4．108，P=0．009）；主视眼术前近视力（LogMAR-0．055±0．218），术后6个月为（LogMAR-0．034±0．187），差异无统计学意义（t=1．051，P=0．334）。术后6个月6mm拟合球面Q值，非主视眼平均为（0．08±0．27），主视眼平均为（0．46±0．27）．两组差异有统计学意义（t=4．301，P=0．000）。非主视眼术后角膜中央区出现高屈光力范围（手术预期视近区域），平均为（5．64±3．05）mm^2；术后6个月，非主视眼4只眼（12．5％）出现正球差，平均均方根值为（-0．204±0．195）μm，与术前比较差异无统计学意义（t=0．532，P=0．600）；主视眼无正球差出现，均方根值为-0．791～-0．083μm，平均（-0．470±0．208）μm，和术前相比负球差明显增加，差异有统计学意义（t=12．622，P=0．000），术后两组的差异有统计学意义（t=9．214，P=0．000）。非主视眼术后6个月调节幅度较术前增加（0．84±0．61）D，主视眼较术前降低（0．10±0．67）D。非主视眼手术后调节力增幅和术后角膜多焦点指数、球差改变具有相关关系。结论多焦点准分子激光原位角膜磨镶术治疗老视前近视安全、有效。多焦点准分子激光原位角膜磨镶术后能够得到一定程度的伪调节，角膜多焦点性质和非球面性是手术后伪调节产生的根源，伪调节和术后负球差的减少有关。

Objective To evaluate the feasibility of multifocal LASIK for the correction of prepresbyopic myopia. Methods In this prospective, comparative case series, thirty-two patients were recruited into the study,mean age was （38. 5 ± 2. 7） years, standard LASIK using Planoscan was performed on the patient＇s dominant eye ,while muitifocal LASIK was performed on the nondominant eye. Routine examinations included distance and near vision, refraction, corneal topography, intraocular pressure, ultrasonic corneal pachymetry, contrast sensitivity function, amplitude of accommodation , depth of defocus, wavefront aberration. Results The mean follow-up duration was 6.67 ± 2. 75 （range, 6 to 11 months ）. In the nondominant eyes, the near visual acuity was statistically significant difference, better in the postoperative visual acuity, however, there was no statistically significant difference between preoperation and postoperation in dominant eyes. The Q value of 6 mm diameter in the nondominant eyes was 0. 081 ± 0. 274 （ range, - 0. 53 to ± 0. 53 ） and 0. 464 ± 0. 266 （ range, - 0. 02 to± 0. 99 ） in the dominant eyes, significant difference were noted between two groups. Topography revealed high degree refractive power zone of （5.64 ± 3.05 ）mm^2 at central cornea in nondominant eyes. The wavefront analysis showed that after the multifocal procedure,a positive spherical aberration was induced , which is opposite to that normally seen following a standard LASIK treatment for myopia. At 6 months, the nondominants eyes attained pseudoaccommodatin of （0. 84± 0. 61 ） diopters （range ,0 to 2. 25 D） , the amplitude of pseudoaccommodation are related to corneal multifocal index, spherical aberration. However, amplitude of accommodation was decreased （0. 10 ± 0. 67 ） diopters in dominant eyes at 6 months visit . Conclusions The results of this study show that multifocal LASIK is safe and effective in preserving near vision for pre-presbyopic myopia patients . Multifocal LASIK are reasonally to induce pseudoaccommodation by decreasing negative spheric aberration.