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社会的发展不外乎波浪式与螺旋式两种模式，准分子激光近视矫正术的手术方法发展也是这样。1983年的PRK（1993），1990年的LASIK（1996），1999年的LASEK（2001），至2003年的epi-LASIK(2004)，括号里的年份为我国开展手术的年份，从中可以明显看到，我国跟随世界步伐明显加快了。PRK手术着眼于角膜上皮层，LASEK和epi-LASIK均是角膜上皮瓣，乍看起来又是迂回到原地，其实不然，它完全符合社会发展的模式，一个轮回前进了一大步。PRK手术的角膜上皮瓣是自己术后再生的，术后刺激大、恢复时间长、haze发生机率较高是其缺点。但术后视觉质量较好，近视矫正度数较高以及术后没有瓣间再裂开的并发症都是它的优点。LASEK手术的出现保持了PRK的优点，减少了PRK的缺点，但手术中毕竟有乙醇化学反应的影响，致使角膜上皮瓣中的基底膜不完整，从这点出发，epi-LASIK不等于没有乙醇的LASEK。为此人们对于epi-LASIK手术的重视与研究是理所当然的。在我院的准分子激光近视矫正手术中，上皮瓣手术（epi-LASIK与LASEK）和角膜基质瓣手术（LASIK）的比例已占40％与60％之比，同时，做epi-LASIK的比例也在逐渐上升。对于epi-LASIK手术的临床研究，已证实手术后的视觉质量比LASIK好，包括视力测定中，16.7％眼术后最佳矫正视力超过术前，高阶像差术后虽有增加，但比LASIK低，对比敏感度比LASIK高，眩光比LASIK少，角膜知觉恢复比LASIK快。从分子生物学研究中证实，epi-LASIK术中角膜基质细胞凋亡较LASEK轻，SMA蛋白较LASEK少，为epi-LASIK术后刺激症状较LASEK小，haze发生率较LASEK少与轻找到病理基础。但不管怎样，epi-LASIK不会完全取代LASEK，因为视网膜脱离手术后、IOL植入术后经不起眼球负压吸引，LASEK就有它的优势。同时，角膜上皮瓣手术也不可能完全替代LASIK，因为LASIK手术中保留了前弹力层，前弹力层存在的价值肯定存在，但其真正的存在意义很值得我们进行深入的研究。
Clinical Thinkings of Subepithelial Excimer Laser Refractive Surgery
Renyuan Chu M.D.
E & ENT hospital affliated with Fudan University
Our society develops either in the way of wave or of spiral, so is the surgery methods of excimer laser refractive surgery. Since our world first invented PRK In 1983 (1993 in China), it took 7 years for the LASIK coming into being (1996 in China), and in 1999 (2001 in China) LASEK was invented, which had been popular until year 2003 (2004 in China) when epi-LASIK was invented. According to the numbers in the bracket, it is easy to see that our country now follows the world in a faster pace. As we know, the PRK procedure lays its emphasis on the epithelial layer of the cornea, while LASEK and epi-LASIK focuses on the corneal epithelial flap, which seems that we have returned to the starting point. In fact we have made a great step forward in this circulation that is coincident with our society’s developing pattern. After PRK surgery, the epithelium has to recover by itself, which then results in more irritations, longer recovery time and higher incidence of haze. But PRK still has its own virtues like better visual quality, more myopia correction ability, and no flap splitting complications. LASEK is better than PRK, but the integrity of corneal basement membrane will be destroyed by the chemical reaction of ethanol. From this point, epi-LASIK is equal to ethanol-free LASEK, so it is natural for people to think highly of it. In our hospital, epi-LASIK and LASEK consists of 40% of the total excimer laser myopia correction procedures, compared to 60% of LASIK, among which epi-LASIK is increasing gradually. Clinical studies on epi-LASIK have proved that it turns out better visual quality than LASIK, including that 16.7% of the eyes has better post-op BSVA than pre-op BSVA; despite an increase of high order aberration, the incidence is still lower than LASIK ; it has better contrast sensitivity , lower incidence of dazzling, and less corneal perception recovery time than LASIK as well. Molecular biology studies also confirm that in epi-LASIK apoptosis of keratocytes and protein α-SMA are less than that in LASEK, which may be the pathological base of its slighter post-op irritation and fewer haze incidence. However, LASEK won’t replaced by epi-LASIK totally, because it is superior in eyes can not withstand negative pressure suction after vitreous-retinal surgery and IOL Implantation. Meanwhile, corneal flap surgery will not completely take the place of LASIK, since the latter has maintained the integrity of Bowman's layer. And it is clear that this layer has its own virtue that deserves our further study.
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