Thickness and immunohistochemistry of LASIK flaps created by different femtosecond lasers in eye-bank corneas

ABSTRACT Purpose: The aim of this study was to compare the corneal cell viability and thickness of LASIK flaps created by 3 femtosecond lasers in eye-bank human corneas. Methods: Forty-five eye-bank human sclerocorneal buttons (15 corneas in each group) were examined after the creation of 120 mm-thick laser-assisted keratomileusis (LASIK) flaps with 150kHz iFS IntraLase™ (IL), Z6 Femto LDV™ (LDV), or 200kHz Wavelight™ FS200 (FS200). The thickness of the flaps was measured using anterior segment optical coherence tomography (AS-OCT; Visante™). Cell viability was blindly evaluated with immunohistochemistry for keratocyte apoptosis using anti-caspase 3 antibodies. Results: The standard deviation from the intended flap thickness was less than 10 mm in all the groups. There was a statistically significant difference in corneas treated with LDV and IL with regard to the flap thickness horizontally at +3.00 mm (p=0.0124), -0.5 mm (p=0.0082), and -1.00 mm (p=0.0425) from the corneal vertex and +0.5 mm from the flap edge (p=0.0240), and those treated with LDV and FS200 with regard to the flap thickness horizontally at -0.5 mm from the corneal vertex (p=0.0082). The mean keratocyte apoptosis numbers were 13.09 ± 1.10, 15.59 ± 3.28, and 17.72 ± 1.49 in corneas treated with IL, FS200, and LDV, respectively (p<0.001). Conclusion: All 3 assessed femtosecond lasers provided predictable LASIK flap thickness. The mean stromal keratocyte apoptosis number was low in all groups.

摘要
研究目的：本研究旨在对比3种飞秒激光（femtosecond lasers）制备的准分子激光原位角膜磨镶术（LASIK, laser-assisted keratomileusis）瓣的角膜细胞活性与厚度，实验材料为眼库来源的人角膜。
方法：分别采用150kHz iFS IntraLase™（简称IL）、Z6 Femto LDV™（简称LDV）及200kHz Wavelight™ FS200（简称FS200）制备120mm厚的LASIK瓣后，对45份眼库人巩膜角膜植片（每组15份角膜）开展检测。使用前节光学相干断层扫描（AS-OCT, Visante™）测量角膜瓣厚度；通过抗半胱天冬酶3抗体实施免疫组织化学检测，以盲法评估角膜细胞活性。
结果：所有组别中，预期角膜瓣厚度的标准差均小于10mm。在角膜顶点旁+3.00mm、-0.5mm、-1.00mm处以及瓣边缘旁+0.5mm的水平角膜瓣厚度指标上，LDV组与IL组间存在统计学显著差异（p值分别为0.0124、0.0082、0.0425、0.0240）；在角膜顶点旁-0.5mm的水平瓣厚度上，LDV组与FS200组间同样存在统计学显著差异（p=0.0082）。IL组、FS200组及LDV组的平均基质角膜细胞凋亡数分别为13.09±1.10、15.59±3.28及17.72±1.49（p<0.001）。
结论：本次评估的3种飞秒激光均可实现可预测的LASIK瓣厚度制备；所有组别中的平均基质角膜细胞凋亡数均处于较低水平。