【作者】 赵金荣；

【导师】 赵少贞；

【作者基本信息】 天津医科大学 ， 眼科学， 2004， 硕士

【摘要】 准分子激光原位角膜磨镶术(laser in situ keratomileusis，LASIK)治疗近视在我国开展仅有6～7年的历史，但其发展速度之快、普及面之广令人惊叹。与准分子激光角膜切削术(photorefractive keratectomy，PRK)相比，LASIK保留了角膜上皮及前弹力层和大部分基质，更符合角膜的解剖生理，术后感染少，疼痛轻，视力恢复快，稳定性和预测性好，尤其适合于中高度近视的治疗。自20世纪90年代以来，已成为首选的屈光矫治术式。对于中高度近视的矫治得到了肯定。然而其创伤愈合反应的机制尚未完全明了，研究多局限在动物实验及人工器官培养的角膜上。近年来应用的角膜共聚焦显微镜可以对角膜进行活体、实时、三维和连续的非侵入性扫描检查，在细胞水平观察角膜的动态变化，并可对角膜各层结构进行直接、准确的厚度测量，使LASIK术后在活体、动态观察人眼角膜创伤愈合反应成为可能。 对于屈光度大于-10D的超高度近视而言，一方面手术切削角膜基质时间较长，切削深度较大，其创伤愈合反应可能较中低度近视更重；另一方面超高度近视本身有着复杂的病理改变，术后发生回退机率较高，也时有报道发生医源性角膜扩张的病例，因此应用共聚焦显微镜观察超高度近视患者LASIK术后角膜形态学的改变一方面可以更深入的理解LASIK术后角膜的创伤愈合反应及其发生机制，另一方面可以分析其主要并发症产生的原因及可能的预防方法。本研究应用共聚焦显微镜对超高度近视患者LASIK手术前后角膜的改变进行前瞻性观察，从细胞水平分析LASIK术后角膜各层的形态改变，角膜细胞的数量变化，并对其相关因素进行分析，探讨LASIK术后角膜创伤愈合反应的发生机制及与创伤愈合相关的并发症的可能原因。天津医科大学硕士学位论文 选择2003年6月至2004年4月于天津医科大学眼科中心准分子激光治疗中心行LAsIK手术的患者31人54眼，术前屈光度介于一1 0.ooD一18.ooD之间。31人(54眼)分别于术前、术后l天、l周、l月、3个月，27人(48眼)于术后6个月行共聚焦显微镜检查，记录患者术前及术后各时间点角膜形态及各层细胞数量的变化，分析屈光手术前及术后各时间点角膜各层细胞的变化规律，及其与屈光状态、角膜感觉的恢复、手术的效果及手术并发症之间的关系。现将研究结果简述如下: 1.超高度近视LASIK术后视力与术前相比明显提高，术后视力逐渐提高，术后6月视力与术前最佳矫正视力相比提高，其差别具有统计学意义，超高度近视行LASIK手术效果可靠。 2.术后1天至1周球镜度数变化较大，术后1月、3月、6月球镜度数呈下降趋势，术后6月球镜度数与术后1周相比差异具有统计学意义，术后6月球镜度数尚未达到稳定;术后各时间点散光差异不具有统计学意义，术后6月散光较术前减少，差异具有统计学意义。 3.超高度近视患者角膜厚度较薄，前基质细胞数、后基质细胞数及内皮细胞数均较中低度近视低，差异具有统计学意义。超高度近视内皮细胞面积变异系数较中低度近视高，六角形细胞百分比较中低度近视低，差异具有统计学意义。 4.LAS工K术后部分患者出现神经营养性上皮病变，可影响或不影响视力，多于术后半年消失，术后10天上皮基底层可见反光增强的小圆形颗粒的沉积，随访期间，沉积颗粒的大小及范围逐渐增多，对视力无影响。 5.LAS工K术后1天，神经数量和形态与术前相比无明显改变，术后l周16眼可见1~2支神经纤维，余角膜未见神经纤维图像，术后3月神经纤维略增多，至术后6月未恢复至术前水平。 6.LASIK术后前弹力层及前基质可出现皱褶，且长期存在，可能是LASIK天津医科大学硕士学位论文手术的亚临床并发症，与术后角膜的不规则散光有关。术后在角膜瓣与基质床的交界处可出现特征性的高反光和较低反光颗粒，颗粒的总体反光强度随访期间逐渐降低。 7.术后1天界面的上下可出现无细胞区，随访期间无细胞区不随时间推移改变。无细胞区的下方可见“激活细胞”，多于术后1周左右反光降低，部分术后1周及1月仍见“激活细胞”及其周围的基质和胶原，激活细胞区深度与角膜瓣厚度呈负相关。 8.内皮细胞数、内皮细胞面积变异系数、六角形细胞百分比手术前后未见明显改变。 9.术后各时间点上皮厚度与屈光度的变化呈负相关，术后上皮厚度的改变可能与术后早期屈光回退有关，术后基质床厚度未见明显改变。 结论: 1.超高度近视患者LASIK术后屈光呈回退趋势，至术后6月尚未达到稳定，视力呈渐进性增加，术后6月视力高于术前最佳矫正视力。 2.超高度近视患者角膜显微形态学存在改变。 3.超高度近视角膜的创伤愈合反应较小，术后早期可出现上皮、基质等部位的改变，微皱褶、界面反光颗粒等长期存在，可能为LASIK手术对角膜的亚临床损伤，对角膜的远期影响不明。 4.上皮的代偿性增厚可能是影响术后早期屈光改变的主要原因，角膜瓣的厚度是影响创伤愈合反应的因素之一，合适厚度的角膜瓣可能降低创伤愈合反应，有助于降低回退的发生率，提高手术的效果。更多还原

【Abstract】 Laser in situ keratomileusis(LASIK) has been adapted to correct myopia in our country for about 6 to 7 years, compared with photorefractive keratectomy(PRK), Laser in situ keratomileusis (LASIK) involves the performing of an anterior cornea! flap (130μm~160μm of thickness) and removal of midstromal tissue by excimer laser photoablation. The preservation of the corneal epithelium, Bowman’s layer and the most parts of anterior stroma makes LASIK safe and effective. Since 1990s it became the first choice of myopic correction. Although the good refractive results have been clearly demonstrated, few articles have been published regarding the wound healing process after LASIK and most of them confined to animal trial and organ cultured cornea. Recently, technological advances led to the development of powerful clinical confocal microscope which allows observation of the living human eye in situ at the cellular level. The confocal microscopy in vivo is an acceptable and reproducible method to detect the changes of corneal stroma and sublayer thickness. It is especially useful in the area of corneal refractive surgery, where it aids to detect the subtle short and long term changes in cornea.When correcting high myopia (refractive error>=10D), people have different views, for the corneal pachymetry is more thinner, and laser ablation is more deeper than low and moderate myopia, the complications rate increases after LASIK. This study evaluates the changes before and after LASIK at cellular level prospectively, analyzes the affecting factors, discusses the wound healing process and the probable method to prevent the complications about it.In this study, 54 eyes of 31 patients (mean preoperative refraction range: -10D to -18.00D) were analyzed. All the patients were examined before LASIK, 1 day, 1week,l month,3 month after LASIK ,48 eyes were also examined 6 months after LASIK. All the scan were reviewed and analyzed. The visual acuity and refractive changes were also analyzed. Results are as following:1. Uncorrected visual acuity evidently increased after LASIK, and uncorrected visual acuity 6 months postoperatively increased compared with the best corrected visual acuity before surgery. The differences were statistically significant.2. spherical refractive diopter changed markedly from 1 day postoperatively to 1 week, decreased gradually afterwards, and didn’t reach a steady state till 6 months postoperatively. The change of spherical refractive diopter negatively correlated with thickness of the epithelium. Astigmatism decreased at 6 months after surgery compared with that before surgery. The differences were statistically significant.3. For high myopia the corneal patchmetry is more thinner, and cell count in anterior stroma, posterior stroma and endothelium is less than that of low and moderate myopia, and the differences were statistically significant. Pleomagthism of endothelium increased and polymagthism decreased compared with low and moderate myopia, The differences were statistically significant.4. After LASIK some patients may have neurotrophic epitheliopathy which may affect visual acuity or not, and disappeared about 6 months postoperatively. 1 week after LASIK, deposits were seen at the basal cells layer, and its area and reflection intensity increased with tune till 6 months, we didn’t find it affect visual acuity.5. Nerve fiber could be seen 1 day after LASIK the same as that before surgery, but most of them disappeared 1 week later, the number of nerve fiber increased but didn’t reach the level before surgery till 6 months postoperatively.6. Microfolds exiting at the anterior stroma and Bowman’s layer. It didn’t change with time and correlated with the irregular astigmatism after LASIK. High and low reflection intensity particles were seen at the corneal flap and stromal bed interface, and the total intensity level decreased with tune and became stead at 6 months postoperatively.7. Acellular area were observed at above and below the interface, and its thickness didn’t change w更多还原