Department of Ophthalmology, Odense University Hospital, Sdr. Boulevard 29, 5000, Odense C, Denmark,
Graefes Arch Clin Exp Ophthalmol. 2013 Nov;251(11):2591-600. doi: 10.1007/s00417-013-2400-x. Epub 2013 Jun 22.
The purpose of this study was to compare corneal subbasal nerve morphology, corneal sensation, and tear film parameters after femtosecond lenticule extraction (FLEX) and small-incision lenticule extraction (SMILE).
A prospective, randomized, single-masked, paired-eye design clinical trial of 35 patients treated for moderate to high myopia with FLEX in one eye and SMILE in the other. In both techniques, an intrastromal lenticule was cut by a femtosecond laser and manually extracted. In FLEX, a LASIK-like flap allowed removal of the lenticule, whereas in SMILE, it was removed through a small incision. In-vivo confocal microscopy was used to acquire images of the central corneal subbasal nerve plexus, from which nerve density, total nerve number, and nerve tortuosity were analyzed. Corneal sensation was measured using Cochet-Bonnet esthesiometry. A visual analog scale, tear osmolarity, non-invasive tear film break-up time (keratograph) tear meniscus height (anterior segment OCT), Schirmer's test, and fluorescein tear film break-up time were used to evaluate tear film and ocular surface symptoms. Patients were examined before and 6 months after surgery.
There were no statistically significant differences in baseline parameters between FLEX and SMILE (p > 0.050). With regard to changes from before to 6 months after surgery, mean reduction in subbasal nerve density was 14.22 ± 6.24 mm/mm(2) in FLEX eyes, and 9.21 ± 7.80 mm/mm(2) in SMILE eyes (p < 0.05). The total number of nerves decreased more in FLEX eyes than in SMILE eyes (p < 0.05). No change was found when comparing tortuosity (p > 0.05). Corneal sensation was reduced with 0.38 ± 0.49 cm in FLEX eyes, and 0.10 ± 0.34 cm in SMILE eyes (p < 0.01). No differences were found between FLEX and SMILE in tear film evaluation tests (p > 0.05). Significantly more patients felt postoperative foreign body sensation in the FLEX eye within the first days after surgery, as compared to the SMILE eye.
Six months after surgery, the less invasive SMILE technique seemed better at sparing the central corneal nerves as compared to FLEX. Corneal sensation was only significantly reduced in FLEX eyes. There were no differences between FLEX and SMILE when comparing tear film evaluation tests 6 months after surgery.
本研究旨在比较飞秒激光透镜切除术（FLEX）和小切口透镜切除术（SMILE）后角膜基底神经形态、角膜感觉和泪膜参数的变化。
一项前瞻性、随机、单盲、配对眼临床试验，纳入 35 例中高度近视患者，每只眼分别接受 FLEX 或 SMILE 治疗。两种技术均通过飞秒激光切割基质透镜，手动提取。在 FLEX 中，采用 LASIK 样瓣去除透镜，而在 SMILE 中，通过小切口去除透镜。应用共焦显微镜获取中央角膜基质下神经丛图像，分析神经密度、总神经数和神经扭曲度。使用 Cochet-Bonnet 触诊仪测量角膜感觉。使用视觉模拟评分、泪液渗透压、非侵入性泪膜破裂时间（角膜地形图）泪膜新月高度（眼前节 OCT）、泪液分泌试验和荧光素泪膜破裂时间评估泪膜和眼表面症状。患者在术前和术后 6 个月进行检查。
FLEX 和 SMILE 组间术前各参数无统计学差异（p>0.050）。与术前相比，术后 6 个月时，FLEX 组角膜基质下神经密度平均下降 14.22±6.24mm/mm²，SMILE 组下降 9.21±7.80mm/mm²（p<0.05）。FLEX 组的总神经数减少多于 SMILE 组（p<0.05）。神经扭曲度无变化（p>0.05）。FLEX 组角膜感觉下降 0.38±0.49cm，SMILE 组下降 0.10±0.34cm（p<0.01）。术后 6 个月时，FLEX 和 SMILE 组的泪膜评估试验无差异（p>0.05）。FLEX 组术后第 1 天至第 3 天，术后异物感明显多于 SMILE 组。
术后 6 个月，与 FLEX 相比，微创 SMILE 技术似乎对中央角膜神经的损伤更小。FLEX 组的角膜感觉仅显著下降。术后 6 个月时，FLEX 和 SMILE 组的泪膜评估试验无差异。
