Objective To evaluate the precision of laser in situ keratomileusis (LASIK) using two different devices, the Esiris excimer and Visx S4-IR laser systems, and small incision lenticule extraction (SMILE) surgery with the VisuMax femtosecond laser system. Methods This was a prospective case control study. Central corneal thickness was measured by using ultrasonic pachymetry before and 1 month after surgery in 274 consecutive eyes of 138 patients with no previous history of surgery. Corneal refractive surgery was then performed on all patients. Among all eyes, 100(51 patients) underwent LASIK with the Esiris excimer laser system; 100(50 patients) underwent LASIK with the Visx S4-IR excimer laser system; and 74(37 patients) underwent SMILE with the VisuMax femtosecond laser system. The changes in central corneal thickness before and after surgery were compared with their theoretically expected values calculated before surgery. The differences between them were defined as the central corneal cutting error, the index of the surgical precision, and were compared for different types of surgery and different magnitudes of refractive errors. An independent sample t test, two-way analysis of variance and Pearson correlation were used for data analysis. Results The extent of myopia, the extent of astigmatism and the central corneal thickness before surgery had no significant effects on the central corneal cutting error. In contrast, the cutting error showed significant differences between groups, suggesting a strong effect based on the equipment and procedure used in the refractive surgery. In the Esiris-LASIK group, there were significant differences (low myopia, t=4.672, P<0.01; moderate myopia, t=10.629, P<0.01; high myopia, t=11.021, P<0.01) between the changes in central corneal thickness and their expected values. Similarly, there were significant differences (low myopia, t=3.910, P<0.01; moderate myopia, t=4.922, P<0.01; high myopia, t=4.807, P<0.01) between the changes in central corneal thickness and their expected values in the Visx-LASIK group. In contrast, the central corneal cutting error was statistically equivalent to zero for both moderate (t=1.158, P>0.05) and high (t= 0.836, P>0.05) myopia in the VisuMax-SMILE group. Conclusion There are significant differences in central corneal cutting error when corneal refractive surgeries are performed with different devices.
刘才远,汤勇,蒋瑜,潘秀珍,汤元昕,陈萍,虞燕. 三种不同设备行屈光手术时的角膜切削误差比较[J]. 中华眼视光学与视觉科学杂志, 2013, 15(11): 680-683.
LIU Cai-yuan,TANG Yong,JIANG Yu,PAN Xiu-zhen,TANG Yuan-xin,CHEN Ping,YU Yan. Investigation of central corneal cutting error in corneal refractive surgery using three different devices. Chinese Journal of Optometry Ophthalmology and Visual Science, 2013, 15(11): 680-683. DOI: 10.3760/cma.j.issn.1674-845X.2013.11.010
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