光学相干断层扫描分析飞秒激光LASIK角膜瓣厚度的可预测性

Predictability of LASIK corneal flap thickness measured by optical coherence tomography in femtosecond laser

目的应用眼前节光学相关断层扫描(optical coherence tomography,OCT)评估飞秒激光LASIK制作的角膜瓣厚度的均一性和可预测性。方法选取南京军区南京总医院的35例(68眼)应用Zeiss VisuMax飞秒激光制作角膜瓣后行LASIK的患者进行前瞻性研究。术前所有患者均进行完善的眼科常规检查,包括角膜地形图、角膜曲率及角膜厚度等。由同一检查医师于术后1周用裂隙灯检查角膜形态,并用眼前节OCT(Visante,Carl Zeiss Meditech)分别测量角膜水平子午线和垂直子午线上距离角膜顶点±0.5mm、±1.5mm、±2.5mm共12个特定点的角膜瓣厚度,比较实际角膜瓣厚度与预设角膜瓣厚度的差异,并比较各对应点之间的实际角膜瓣厚度差异。结果术后1周35例(68眼)裂隙灯检查均未见Haze或角膜瓣皱褶,所有特定点的角膜瓣厚度均具有高度的可预测性。术前预设角膜瓣厚度为120μm,术后与预计值差值≤6μm的测量点占全部测量点的53.2%,差值≤10μm的测量点占全部测量点的76.8%。术后角膜瓣厚度为124.16μm,标准差为8.17～10.09μm,均一性为123.10～126.09μm,鼻侧与颞侧、上方与下方、中心区域与旁中心区域的角膜瓣厚度差异均无统计学意义(均为P>0.05)。结论 OCT是无创、简捷、可靠的角膜瓣形态检测手段。LASIK术后眼前节OCT检查表明:VisuMax飞秒激光LASIK制作的角膜瓣厚度具有很好的均一性和可预测性。

Objective To evaluate the uniformity and predictability of LASIK flap created with a femtosecond laser using anterior segment optical coherence tomography （OCT）. Methods A total of 58 consecutive eyes of 35 patients who had flaps created with the VisuMax femtosecond laser （ Carl Zeiss Meditec） underwent LASIK surgery in Nanjing General Hospital of Nanjing Military Region were selected for prospective stud- y. Preoperative examinations included corneal topography, corneal curvature and corne- al thickness for all the patients. The same surgeon checked the corneal shape 1 week postoperative with slit lamp. The flap thickness was measured using anterior segment OCT （Visante, Carl Zeiss Meditec） at postoperative one week. Flap thickness was meas- ured at ±0.5mm, ± 1.5 mm and ±2.5 mm zone from the flap center,and along the 0° and 90°meridian （a total of 12 points）. The differences between the actual thickness of the corneal flap and the preset corneal flap thickness were compared, and the corre- sponding points＇ differences of corneal flap thickness between postoperative each oth- er. Results There was no haze or flap fold in the slit lamp examination at postopera- tive one week. All positions of corneal flap thickness had a high degree of predictability. 53.2% of the measuring points had a difference value within 6 pμm compared with the expected value,and the measuring points which had a difference value within 10μm ac- counted for 75.8% of all. Thickness standard deviations varied from 8.17 μm to 10.09μm and uniformity was from 123.10 μm to 125.09 μm. There was no statistical differ- ence in corneal flap thickness between the nasal side versus temporal side, the superior side versus inferior side, or the pericentral area versus central area of the corneal flap （ all P 〉 0.05 ）. Conclusion OCT is noninvasive, simple, reliable means of shape de-tection of corneal flap. Postoperative anterior segment OCT examination shows that corneal flap thickness produced with VisuMax femtosecond laser LASIK possesses the good uniformity and predictability.