高度近视行SMILE与FS-LASIK术后视觉质量比较
魏然, 琼芹, 邱乐梅, 张小兰, 孙成淑, 王顺清, 邓应平
610041 成都,四川大学华西医院
通信作者:邓应平,Email:dyp558@163.com
摘要

目的 比较飞秒激光小切口角膜基质透镜取出术(SMILE)和飞秒激光制瓣的准分子激光原位角膜磨镶术(FS-LASIK)矫正高度近视术后的视觉质量。方法 前瞻性非随机对照研究。收集四川大学华西医院眼科中心行近视矫正术的高度近视患者,按照其手术方式分为SMILE组21例(41眼)和FS-LASIK组19例(38眼)。常规检查裸眼视力(UCVA)、最佳矫正视力(BCVA)、屈光度、眼压、对比敏感度(CS)、角膜高阶像差和屈光矫正对生活质量的影响问卷(QIRC)评分,于术后1 d、1周、1个月、3个月和6个月随访复查。采用独立样本 t检验或Mann-Whitney U检验进行统计学分析。结果FS-LASIK组和SMILE组的安全指数分别为1.00±0.23和1.00±0.12。术前SMILE组12.0 cpd的LogCS值高于FS-LASIK组( t=2.137, P=0.035),SMILE组3.0 cpd的LogCS值术后6个月与术前变化量高于FS-LASIK组( t=2.843, P=0.008),其余频率差异均无统计学意义。FS-LASIK组的总高阶像差、三阶彗差和四阶球差术后6个月与术前的变化量高于SMILE组,差异有统计学意义( t=-7.587, P<0.001; t=-4.127, P<0.001; t=10.068, P<0.001)。2组之间术后3、6个月2个时间点QIRC量表评分与术前的变化量比较,差异无统计学意义。结论 SMILE和FS-LASIK均能安全地矫正高度近视。SMILE术后低频空间频率对比敏感度恢复情况优于FS-LASIK。SMILE与FS-LASIK均使角膜的高阶像差增加,后者引入了更多的彗差和球差。

关键词: 飞秒激光小切口角膜基质透镜取出术; 准分子激光原位角膜磨镶术; 飞秒激光; 高度近视; 视觉质量
Visual and refractive outcomes of SMILE and FS-LASIK for high myopia
WEI Ran, ZHENG Qiongqin, QIU Lemei, ZHANG Xiaolan, SUN Chengshu, WANG Shunqing, DENG Yingping.
Department of Ophthalmology, West China Hospital of Sichuan University, Chengdu 610041, China
Corresponding author: DENG Yingping, Email:dyp558@163.com
Abstract

Objective To compare the visual quality of small-incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) after correction for high myopia.Methods In this prospective non-randomized case-controlled study, patients were divided into a SMILE group (21 patients, 41 eyes) and a FS-LASIK group (19 patients, 38 eyes) based on the surgical method at the Department of Ophthalmology, West China Hospital. Routine ophthalmic examinations were performed.The patients were followed 6 months to monitor uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive error, intraocular pressure, contrast sensitivity, corneal higher order aberrations, and scores for Quality of Life Impact of Refractive Correction Questionnaire (QIRC). Statistical analyses were performed using an independent samples t-test or Mann-Whitney U test.Results The safety index was 1.00±0.23 in the FS-LASIK group and 1.00±0.12 in the SMILE group. Log contrast sensitivity (LogCS) of 12.0 cycles per degree (cpd) was significantly higher in the SMILE group compared to the FS-LASIK group before surgery ( t=2.137, P=0.035). The change in LogCS for 3.0 cpd at six months after surgery was significantly greater in the SMILE group compared to the FS-LASIK group ( t=2.843, P=0.008), but other differences were statistically insignificant. The changes in total higher order aberrations, the third order coma, and the fourth order spherical aberration were greater in the FS-LASIK group than in the SMILE group during the same period ( t=-7.587, P<0.001; t=-4.127, P<0.001; t=10.068, P<0.001; respectively). There was no significant difference in the amount of change in the QIRC scores between the two groups at 3 and 6 months postoperation.Conclusion Both SMILE and FS-LASIK can safely correct high myopia. Spatial frequency contrast sensitivity recovers better after SMILE surgery compared to FS-LASIK. Both SMILE and FS-LASIK increase corneal higher-order aberrations, but the FS-LASIK procedure induces more coma and spherical aberrations than SMILE.

Keyword: Small-incision lenticule extraction; Laser in situ keratomileusis; Femtosecond laser; High myopia; Visual quality

近年来, 近视成为全球发病率最高的屈光性疾病, 非洲地区的发病率为10%~20%, 欧洲和北美洲为30%~40%, 在亚洲发病率更为显著, 为70%~ 90%[1, 2, 3, 4, 5], 而其中, 高度近视占全球近视人群总数的27%~33%[6]。随着科技的发展和进步, 屈光手术的安全性得到极大的提升, 越来越多的屈光不正患者选择屈光手术来矫正近视。高度近视的矫正手术又分为角膜手术、晶状体手术和巩膜手术。角膜手术目前分为两大类:表层切削术和基质切削术。表层角膜手术随着矫正度数的增大, 其角膜雾状混浊和屈光回退的概率增大。因此矫正高度近视更多的是采用基质角膜切削术。目前, 具有代表性的角膜基质层手术方式为飞秒激光小切口角膜基质透镜取出术(SMILE)和飞秒激光制瓣的准分子激光原位角膜磨镶术(Femtosecond laser-assisted LASIK, FS-LASIK)。许多既往研究已经表明SMILE和FS-LASIK均具有较好的安全性、有效性及可预测性[7, 8, 9, 10, 11, 12]。但是关于2种手术方式术后的客观及主观视觉质量的全面分析仍较少。本研究采用对比敏感度、高阶像差和屈光矫正对生活质量的影响问卷(The Quality of Life Impact of Refractive Correction Questionnaire, QIRC)全面评估2种手术方式对患者的客观和主观视觉质量的影响。

1 对象与方法
1.1 对象

收集2015年8月至2016年1月于四川大学华西医院近视手术中心行屈光矫正术的患者, 根据患者检查结果及自身意愿, 分别行SMILE手术21例(41眼)、FS-LASIK手术19例(38眼), 手术前均签署手术知情同意书。入选标准:①年龄18~40岁; ②无眼部疾病史、外伤史和严重全身疾病史; ③最佳矫正视力(BCVA)≥ 1.0, 2年内屈光度稳定(增长≤ 0.50 D); ④球镜度为-6.00~-10.00 D, 柱镜度在3.00 D以内; ⑤角膜接触镜配戴者停戴2周以上。

1.2 术前检查

常规检查, 包括:①裸眼视力(UCVA)、BCVA, 自然瞳孔和散瞳电脑验光、检影验光及插片验光; ②裂隙灯显微镜检查、散瞳后双目间接检眼镜眼底检查; ③超声角膜测厚仪测量中央角膜厚度及眼轴长度; ④角膜荧光素染色、泪膜破裂时间和无麻醉情况下泪液分泌试验; ⑤非接触式眼压计测量眼压; ⑥主视眼判断; ⑦Sirius眼前节分析仪(意大利CSO公司)测量角膜地形图和眼前节参数。

非常规检查, 包括:①Sirius眼前节分析仪测量角膜像差; ②暗视下对比敏感度检查(CSV-1000E, 美国Vector Vision公司); ③QIRC问卷。

所有验光检查由同一位高级验光师完成, 计量资料由同一位眼科技师测量, 测量3次取平均值。

1.3 手术方法

2种手术方式均由同一位经验丰富的主任医师完成。

1.3.1 SMILE 手术步骤:术眼使用0.4%盐酸奥布卡因滴眼液(日本Santen公司)表面麻醉后置于全飞秒激光屈光手术系统(VisuMax, 德国Carl Zeiss Medic公司), 显微镜下中心对位, 开启负压吸引固定术眼, 启动飞秒激光, 先后完成透镜后表面、前表面及角膜切口制作, 显微镜下分离并取出透镜, 完成手术。

手术参数:角膜11-12点钟位的2 mm微切口, 角膜帽的厚度为120 μ m, 帽的直径为7.5 mm, 基质透镜直径6.5 mm, 透镜边切及微切口边切角为90° 。

1.3.2 FS-LASIK 手术步骤:术眼使用0.4%盐酸奥布卡因滴眼液表面麻醉后置于全飞秒激光屈光手术系统下完成角膜瓣制作, 然后转移患者至准分子激光机(Eye-Q, WaveLight)系统, 显微镜下虹膜恢复器钝性分离角膜瓣, 在跟踪系统护航下完成准分子激光角膜切削, 扫描完毕后复位角膜瓣, 无菌硬质眼罩包眼。

手术参数:角膜瓣边切角为110° , 角膜瓣厚度110 μ m、直径8 mm, 角膜瓣蒂位置根据散光轴向相应调整, 常规位于角膜12点钟位, 视区6.0~6.5 mm, 修边0.5 mm。

1.4 术后复查

术后常规随访:术后1 d裂隙灯显微镜检查后测量UCVA、眼压, 术后1周、1个月、3个月、6个月随访行UCVA、屈光度、裂隙灯显微镜、眼压、角膜地形图、暗视下对比敏感度检查; 于术后1个月、3个月及6个月进行QIRC问卷评分, 术后6个月测量BCVA和角膜像差。

1.5 统计学方法

前瞻性非随机对照研究。采用SPSS 19.0软件对数据进行统计学分析。计量资料采用Shapiro-Wilk检验进行正态分布检验, 服从近似正态分布的数据以x± s表示, 偏态分布以中位数(四分位数间距)[MQR)]表示。不同空间频率值对比敏感度取对数进行统计学分析。计量资料组间比较采用独立样本t检验或Mann-Whitney U检验, 计数资料比较采用卡方检验。以P< 0.05为差异有统计学意义。

2 结果
2.1 一般资料

SMILE组21例(41眼), 年龄[24(7)]岁, 其中女性15例(29眼)。FS-LASIK组19例(38眼), 平均年龄[24.5(7)]岁, 其中女性12例(24眼)。2组患者性别、年龄分布差异无统计学意义(χ 2=0.472, P=0.492; Z=-0.645, P=0.519)。

2.2 视力及屈光度

患者手术均顺利完成, 术后均获得了较为满意的UCVA。术前2组球镜度、等效球镜度(SE)、UCVA差异具有统计学意义, 而术后UCVA、术前及术后BCVA差异均无统计学意义(见表1)。术后6个月随访结果显示, SMILE组安全指数为1.00± 0.12, FS-LASIK组安全指数为1.00± 0.23。

表1 2组之间术前及术后6个月视力和屈光状态比较 Table 1 Visual and refractive outcomes at preoperative and postoperative
2.3 对比敏感度

对比敏感度值均在暗视条件下进行测量。术前SMILE组12.0 cpd的LogCS值高于FS-LASIK组, 且差异有统计学意义(t=2.137, P=0.035), 其余空间频率的LogCS值2组间差异无统计学意义。2组研究对象术后6个月与术前LogCS差值的比较见表2, SMILE组3.0 cpd的LogCS值术后6个月与术前差值高于FS-LASIK组(t=2.843, P=0.008)(见表2), 其余空间频率的差值差异均无统计学意义。所有研究对象的术后对比敏感度值均呈现出随时间延长而上升的趋势, 见图1-2。

表2 2组之间术后6个月与术前对比敏感度对数值差值比较(x± s Table 2 Change between preoperative and postoperative contrast sensitivities (x± s

图1 SMILE组对比敏感度变化(41眼)。在恢复期, 对比敏感度有升高趋势, 3 cpd处对比敏感度的对数值与术前差异有统计学意义(t=-3.494, P=0.002)Figure 1 Contrast sensitivity values before and after SMILE (41 eyes). During the recovery period, the postoperative contrast sensitivity of the SMILE group tended to increase. The logCS value of 3.0 cpd at 6 months after SMILE was higher than the preoperative level (t=-3.494, P=0.002). At other postoperative times, the logCS values were not significantly different from preoperative levels. SMILE, small-incision lenticule extraction; logCS, logarithm of the contrast sensitivity; cpd, cycles per degree.

图2 FS-LASIK组对比敏感度变化(38眼)。在恢复期, 对比敏感度有升高趋势, 但均与术前差异无统计学意义Figure 2 Contrast sensitivity values before and after FS-LASIK (38 eyes). During the recovery period, the postoperative contrast sensitivity of the FS-LASIK group tended to increase. However, none of the logCS values at any of the tested cpds was significantly different from the preoperative value. FS-LASIK, femtosecond laser in situ keratomileusis; logCS, logarithm of the contrast sensitivity; cpd, cycles per degree.

2.4 波前像差

采用Sirius眼前节分析仪测量研究对象术前与术后6个月的角膜像差, 取瞳孔直径为6 mm时总高阶像差、三阶像差(彗差和三叶草差)、四阶像差(球差和四叶草差)进行对比, 其中球差转化为绝对值进行统计分析。术前SMILE组四叶草差小于FS-LASIK组, 差异有统计学意义; 术后6个月FS-LASIK组总高阶像差、彗差、三叶草差、球差和四叶草差高于SMILE组, 差异有统计学意义(见表3)。术后6个月与术前高阶像差的差值如图3所示, FS-LASIK组的总高阶像差、三阶彗差和四阶球差的手术前后差值均高于SMILE组, 差异有统计学意义。2种手术方式均增加了角膜源性高阶像差, FS-LASIK较SMILE引入了更多的彗差和球差。

2.5 QIRC量表

QIRC问卷是目前常用的评估屈光不正患者主观感受的可靠量表之一[13]。该量表分为20项, 涵盖了视功能、经济负担、舒适度、心理负担等内容。图4显示了研究对象各个时间点QIRC问卷评分的变化, 尽管SMILE组呈现轻微上升趋势, FS-LASIK组呈现下降趋势。但2组研究对象QIRC评分术后3个月与术前的差值及术后6个月与术前的差值比较差异无统计学意义(t=1.066, P=0.290; t=0.375, P=0.710)。

表3 2组之间手术前后高阶像差对比(x± s Table 3 Preoperative and postoperative corneal aberrations (x± s)

图3 2组之间术后6个月与术前高阶像差的差值比较。FS-LASIK组总高阶像差、彗差、球差术后6个月与术前的差值较SMILE组大Figure 3 Change between preoperative and postoperative aberrations. The change between preoperative and postoperative total higher-order aberrations(HOAs), coma and spherical aberration were higher in the femtosecond laser in situ keratomileusis (FS-LASIK) group than in the small-incision lenticule extraction (SMILE) group.

图4 术前及术后各个时间点屈光矫正对视觉质量影响(QIRC)问卷评分变化。虽然SMILE组显示了一种上升的趋势, FS-LASIK组显示了下降的趋势, 但各个时间点2组间差异无统计学意义Figure 4 Change between preoperative and postoperative Quality of Life Impact of Refractive Correction Questionnaire (QIRC) score. Although the SMILE group showed a slight upward trend, FS-LASIK group showed a downward trend, but there was no significant difference in the change between the two groups at each time point. pre, preoperative; 1 m, 1 month postoperative; 3 m, 3 months postoperative, 6 m, 6 months postoperative.

3 讨论

随着时代的进步、技术的发展, 屈光手术的目的不再仅仅是获得良好的UCVA, 视觉质量越来越成为患者和医师共同追求的方向。SMILE和FS-LASIK作为基质角膜屈光手术的代表, 是目前高度近视患者在行角膜屈光手术时的主要选择。本研究通过对比敏感度、波前像差和QIRC问卷评分来评估该2种术式对患者客观和主观视觉质量的影响。

对比敏感度是屈光术后视功能改变的敏感指标[14], 它能很好地评估患者的客观视觉质量。本研究中, 研究对象均为高度近视患者, 术前对比敏感度在使用框架眼镜矫正至BCVA的条件下测量。框架镜片的有效光学面积小, 视网膜上成像的范围减小, 导致周边离焦现象加重, 造成患者视物变形。FS-LASIK组术前SE高于SMILE组, 这也是术前FS-LASIK组12.0 cpd的LogCS值低于SMILE组的可能原因之一。2组研究对象术后6个月与术前的差值比较结果显示, SMILE组3.0 cpd的LogCS差值高于FS-LASIK组, 其余空间频率的差值差异无统计学意义。值得注意的是, 图1显示SMILE组术后6个月3.0 cpd的LogCS值也高于术前水平, 差异有统计学意义, 说明在3.0 cpd上, 相同时间内, SMILE组的恢复优于FS-LASIK组, 术后6个月甚至优于术前水平。

高阶像差是影响视网膜成像清晰与否的一个重要因素, 以往一些研究显示, 总高阶像差、彗差、球差和高阶散光均在屈光术后升高[15, 16, 17, 18]。本研究术后6个月与术前差值的比较显示, FS-LASIK较SMILE引入了更多的彗差和球差。SMILE手术仅通过一个2 mm的角膜切口取出微透镜, 相较于FS-LASIK术的C型角膜瓣, 对角膜生物力学的影响更小, 减少了角膜瓣制作、复位及恢复过程中引入的术源性像差。同时, SMILE术激光扫描过程中采用低负压、非压平吸引模式, 更利于患者注视, 而FS-LASIK术准分子激光扫描过程中使用的是红外虹膜跟踪模式, SMILE术中因眼球转动引起的散光和偏心切削更少, 这也是2种手术方式术后高阶像差差异的原因之一[15]。也有研究表明, 术源性的球差与患者的术前屈光度呈正相关[19]。本研究中, FS-LASIK组术前SE大于SMILE组术前SE, 差异有统计学意义, 这也可能是FS-LASIK组术后球差增加量较SMILE组大的一个原因。高阶像差也会影响对比敏感度, 这也解释了2组研究对象术后对比敏感度的差异。

QIRC问卷可用于评估各种不同屈光矫正方式对患者生活质量的影响[13]。本研究中, SMILE组术后评分较术前高, 且随着时间推移呈现增高趋势; FS-LASIK组术后较术前短暂降低, 随着恢复时间的延长, 再次呈现缓慢下降趋势。但2组研究对象术后3个月与术前差值及术后6个月与术前差值差异无统计学意义, 说明手术方式本身对患者生活质量的影响是无差别的。

综上, SMILE和FS-LASIK均能安全地矫正高度近视。SMILE术后低频空间频率对比敏感度恢复优于FS-LASIK。SMILE与FS-LASIK均增加了角膜的高阶像差, FS-LASIK较SMILE引入了更多的彗差和球差。

本研究样本量和随访时间有限, 可能导致结果存在偏差。得到进一步的结果仍需进行大样本量、随机、多中心的临床研究。

利益冲突申明 本研究无任何利益冲突

作者贡献声明 魏然:收集数据, 资料分析及解释, 撰写论文, 对编辑部的修改意见进行修改。郑琼芹、邱乐梅、张小兰、孙成淑、王顺清:参与收集数据, 修改论文并参与编辑部修改意见的修改。邓应平:课题设计, 资料分析及解释, 修改论文并参与编辑部修改意见的修改

The authors have declared that no competing interests exist.

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