Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

Purpose: To compare the stromal bed surface quality and the accuracy of dissection depth after deep lamellar cuts using the Leonardo Da Vinci (LDV) femtosecond laser (Z6) and the ONE Microkeratome. Methods: Deep lamellar cuts were performed on nine human donor corneoscleral buttons: five with the LDV femtosecond (FS) laser (Z6) (Ziemer) and four with the ONE Microkeratome (MK) (Moria). Corneal thickness was measured with ultrasound pachymetry before and after the dissection. The Stromal bed quality was evaluated using light microscopy (n = 4) and scanning electron microscopy (SEM) (n = 9). The surface roughness on SEM images was graded on the scale of 1 (smoothest) to 5 (roughest) by four observers, blinded to the method used. Particle analysis on the SEM images was performed in order to have an objective measure of smoothness. Results: The achieved dissection depth using the FS laser was 496.4 ± 46.4 µm when attempting 500 µm and 474 ± 60 µm with the microkeratome when attempting 350 µm. Histological evaluation of the corneoscleral buttons by both light and electron microscopy showed significantly smoother surface using the FS laser compared to the microkeratome. There were fewer and smaller particles observed in the SEM images of FS laser cut buttons (p < 0.001).The average observer based score of anterior surface roughness (50×) was 2.2 for the FS laser and 3.9 for the microkeratome dissections (p < 0.001). Conclusions: The LDV femtosecond laser (Z6) platform is capable of creating deep corneal lamellar dissection with smoother surface quality and with more predictable cut depth as compared to the One Microkeratome.目的：比较使用达芬奇飞秒激光（Leonardo Da Vinci, LDV）与ONE微型角膜刀实施深层板层切削后，角膜基质床表面质量与切削深度的准确性。 方法：对9枚人供体角巩膜植块实施深层板层切削：其中5枚采用LDV飞秒激光（femtosecond laser, FS, Z6型，Ziemer公司），4枚采用ONE微型角膜刀（MK, Moria公司）。分别于切削前后使用超声角膜测厚仪测量角膜厚度。采用光学显微镜（n=4）与扫描电子显微镜（scanning electron microscopy, SEM, n=9）评估基质床质量。由4名对手术方式不知情的观察者，以1分（最光滑）至5分（最粗糙）的评分标准对SEM图像的表面粗糙度进行分级。同时对SEM图像开展颗粒分析，以实现平滑度的客观量化评估。 结果：当目标切削深度为500μm时，飞秒激光组实际切削深度为496.4±46.4μm；微型角膜刀组目标切削深度为350μm时，实际切削深度为474±60μm。光学显微镜与电子显微镜的组织学评估结果显示，飞秒激光组切削后的角膜基质床表面平整度显著优于微型角膜刀组。飞秒激光组切削植块的SEM图像中观察到的颗粒更少、体积更小（p<0.001）。观察者对前表面粗糙度（50倍放大）的平均评分显示，飞秒激光组为2.2分，微型角膜刀组为3.9分（p<0.001）。 结论：相较于ONE微型角膜刀，LDV飞秒激光（Z6型）平台可实现表面更光滑、切削深度可预测性更佳的深层角膜板层切削。