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Title: [Comparison of corneal epithelial remodeling after small incision lenticule extraction and femtosecond laser-assisted LASIK].
Author: Wang Y, Zhang XF, Qian YF, Luo BG, Li C, Yang XL.
Journal: Zhonghua Yan Ke Za Zhi; 2020 Feb 11; 56(2):93-102. PubMed ID: 32074819.
Abstract:
Objective: To investigate the corneal epithelial thickness changes between small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK), study the related factors and analyze the relationship between the changes in corneal epithelial thickness and corneal aberration. Methods: This case control study included 59 patients (118 eyes), 27 males and 32 females, aged 25.64±5.57 years, who were scheduled for SMILE or FS-LASIK for treatment of myopia with or without myopic astigmatism at the First Affiliated Hospital of Soochow University between October 2016 and May 2017. All patients were divided into two groups according to the surgery. Epithelial thickness was obtained in nine zones with Fourier-domain optical coherence tomography across a 5-mm diameter centered by the pupil before surgery and at 1 week, 1 month, 3 months and 6 months postoperatively. The observed changes were analyzed by linear-regression analysis with the central corneal thickness decrement, ablation rate and corneal aberration. Comparison between two groups was analyzed by independent sample t-test, analysis of variance and Mann-Whitney U test. Results: There was no significant difference in corneal epithelial thickness of nine zones between SMILE and FS-LASIK for low to moderate myopia (manifest refraction sphere equivalent<-6.00 diopters) and high myopia (manifest refraction sphere equivalent ≥-6.00 to -10.00 diopters), respectively, before surgery (P>0.05). At 1 month, no significant difference existed in corneal epithelial thickness increment in nine zones between FS-LASIK and SMILE for low to moderate myopia (P>0.05), but a larger increase was observed in the superior (t=2.670, P=0.010), superonasal (t=2.506, P=0.015) and nasal (t=2.831, P=0.007) zones following FS-LASIK [(4.2±3.2), (3.4±2.7) and (3.7±2.5) μm] than SMILE [(2.2±2.2), (1.6±2.5) and (1.7±2.6) μm] for high myopia. At 3 months, a larger increase in corneal epithelial thickness was observed in the superior (t=2.703, P=0.009) zone following FS-LASIK than SMILE for low to moderate myopia, and the same increase was observed in the central (t=2.660, P=0.010), superior (t=3.229, P=0.002), nasal (t=2.420, P=0.019), inferonasal (t=2.651, P=0.011), inferotemporal (t=2.153, P=0.036) and superotemporal (t=2.281, P=0.027) zones after FS-LASIK [(6.7±2.6), (5.0±2.1), (3.9±1.9), (4.8±1.8), (7.5±2.5) and (6.4±2.7) μm] than SMILE [(4.7±2.9), (2.9±2.5), (2.4±2.4), (3.3±2.2), (6.0±2.4) and (4.8±2.4) μm] for high myopia. At 6 months, a larger increase in corneal epithelial thickness was observed in the superior (t=3.340, P=0.001) and nasal (t=1.952, P=0.055) zones following FS-LASIK than SMILE for low to moderate myopia, and the same increase was observed in the superior (t=2.332, P=0.024) and inferonasal (t=2.172, P=0.034) zones after FS-LASIK than SMILEfor high myopia. The central corneal thickness decrement after SMILE was much more than FS-LASIK both in the low to moderate myopia and high myopia groups (P<0.05). The average corneal epithelial thickness increment correlated positively with the central corneal thickness decrement and ablation rate at 1 month, 3 months and 6 months postoperatively (P<0.01). For SMILE, the total higher orders aberration (0.81±0.26, 0.79±0.28 and 0.81±0.31) and spherical aberration (0.50±0.21, 0.48±0.20 and 0.52±0.23) were less than FS-LASIK (0.97±0.34, 0.97±0.33 and 0.93±0.32; 0.72±0.25, 0.66±0.30 and 0.71±0.25) at 1 month, 3 months and 6 months postoperatively (P<0.05). Furthermore, the corneal aberration increment correlated positively with the average corneal epithelial thickness increment (P<0.05). Conclusions: The corneal epithelial thickness increment after SMILE was less than FS-LASIK. SMILE had better uniformity of the corneal epithelial thickness increment at the observed zones, which may explain the finding that the postoperative spherical aberration of SMILE was less than FS-LASIK. (Chin J Ophthalmol, 2020, 56:93-102). 目的： 探讨飞秒激光小切口基质内透镜取出术（SMILE）与飞秒激光辅助准分子激光原位角膜磨镶术（FS-LASIK）后角膜上皮厚度变化特点及其影响因素，分析角膜上皮厚度变化与角膜像差的关系。 方法： 病例对照研究。收集2016年10月至2017年5月苏州大学附属第一医院眼科接受SMILE或FS-LASIK的近视眼散光患者59例（118只眼），其中男性27例，女性32例，年龄（25.64±5.57）岁。根据接受的手术分为两组，SMILE组34例（68只眼），FS-LASIK组25例（50只眼）。各组患者按等效球镜度数是否≥-6.00 D分为中低度及高度患者。傅立叶域相干光层析成像仪检测患者术前、术后1周及1、3、6个月的角膜上皮厚度。将角膜中央直径5 mm范围分为9个区域测量上皮厚度，采用线性回归分析上皮厚度变化值与中央角膜厚度减少量、切削比及角膜像差的关系；采用独立样本t检验、方差分析及Mann-Whitney U检验分析组间数据的差异。 结果： 术前两组中的中低度和高度患者年龄以及屈光状态、9个区域角膜上皮厚度差异均无统计学意义（P>0.05）。术后1个月时，FS-LASIK组中低度患者9个区域角膜上皮增厚量与SMILE差异无统计学意义（P>0.05），FS-LASIK组高度患者在上方（t=2.670）、鼻上（t=2.506）和鼻侧（t=2.831）区角膜上皮厚度增加量[（4.2±3.2）、（3.4±2.7）、（3.7±2.5）μm]较SMILE组[（2.2±2.2）、（1.6±2.5）、（1.7±2.6）μm]大（P<0.05）。术后3个月时，FS-LASIK组中低度患者在上方区角膜上皮为厚度增加量（2.4±2.9）μm，较SMILE组（0.7±2.1）μm大（t=2.703，P=0.009），FS-LASIK组高度患者在中央（t=2.660）、上方（t=3.229）、鼻侧（t=2.420）、鼻下（t=2.651）、颞下（t=2.153）及颞上（t=2.281）区角膜上皮厚度增加量[（6.7±2.6）、（5.0±2.1）、（3.9±1.9）、（4.8±1.8）、（7.5±2.5）、（6.4±2.7）μm]较SMILE组[（4.7±2.9）、（2.9±2.5）、（2.4±2.4）、（3.3±2.2）、（6.0±2.4）、（4.8±2.4）μm]大（P<0.05）。术后6个月时，FS-LASIK组中低度患者在上方（t=3.340）及鼻侧（t=1.952）区角膜上皮厚度增加量[（1.9±2.6）、（1.2±1.8）μm]较SMILE[（0.1±2.3）、（0.1±2.3）μm]大（P<0.05），FS-LASIK组高度患者在上方（t=2.332）及鼻下（t=2.172）区角膜上皮厚度增加量[（4.1±1.9）、（4.5±1.7）μm]较SMILE[（2.6±2.7）、（3.1±2.8）μm]大（P<0.05）。SMILE组中低度和高度患者透镜中央厚度[（101.53±17.17）、（134.13±11.34）μm]均明显大于FS-LASIK激光切削深度[（71.19±12.54）、（116.96±10.39）μm]（P<0.05）。SMILE组与FS-LASIK组术后1、3、6个月时平均角膜上皮厚度增加量均与中央角膜厚度减少量及切削比呈正相关（P<0.01）。术后1、3、6个月时SMILE组总高阶像差（0.81±0.26、0.79±0.28、0.81±0.31）、球差（0.50±0.21、0.48±0.20、0.52±0.23）均低于FS-LASIK组总高阶像差（0.97±0.34、0.97±0.33、0.93±0.32）、球差（0.72±0.25、0.66±0.30、0.71±0.25），SMILE组与FS-LASIK组角膜像差增加量与平均角膜上皮厚度增加量呈正相关（P<0.05）。 结论： SMILE术后角膜上皮厚度增加小于FS-LASIK，且各区域角膜上皮厚度增加的均一性好于FS-LASIK。SMILE术后球差小于FS-LASIK可能与之相关。（中华眼科杂志，2020，56：93-102）.

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