Kamiya Kazutaka, Miyata Kazunori, Tokunaga Tadatoshi, Kiuchi Takahiro, Hiraoka Takahiro, Oshika Tetsuro
Department of Ophthalmology, University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Cornea. 2004 Nov;23(8 Suppl):S59-64. doi: 10.1097/01.ico.0000136673.35530.e3.
To review the time course of corneal anteroposterior shift and refractive stability after myopic excimer laser keratorefractive surgery.
We examined 65 eyes undergoing photorefractive keratectomy (PRK) and 45 eyes undergoing laser in situ keratomileusis (LASIK). Corneal elevation maps and pachymetry were obtained by scanning-slit corneal topography before; 1 week; and 1, 3, 6, and 12 months after surgery.
Both PRK and LASIK induced significant forward shifts of the cornea. Corneal forward shift was progressive up to 6 months after PRK, but no progression was seen after LASIK. Progressive thinning and expansion of the cornea were not observed after either procedure. The amount of corneal forward shift showed a significant negative correlation with preoperative corneal thickness (r = -0.586; P < 0.01) and a significant positive correlation with the amount of myopic correction (r = 0.504; P < 0.01). A significant correlation was found between the amount of forward shift and the degree of myopic regression after surgery (r = -0.347; P < 0.05).
Myopic PRK and LASIK induce significant forward shifts of the cornea, which are not true corneal ectasia. Eyes with thinner corneas and higher myopia requiring greater ablation are more predisposed to anterior protrusion of the cornea. Corneal forward shift was progressive up to 6 months after PRK but not progressive after LASIK. Forward shift of the cornea can be one of the factors responsible for myopic regression after surgery.
回顾准分子激光角膜屈光手术后角膜前后移位的时间进程及屈光稳定性。
我们检查了65例行光性屈光性角膜切削术（PRK）的眼和45例行准分子原位角膜磨镶术（LASIK）的眼。术前、术后1周、1个月、3个月、6个月及12个月通过扫描裂隙角膜地形图获取角膜高度图和角膜厚度测量值。
PRK和LASIK均导致角膜显著向前移位。PRK术后角膜向前移位持续进展至6个月，但LASIK术后未见进展。两种手术术后均未观察到角膜进行性变薄和扩张。角膜向前移位量与术前角膜厚度呈显著负相关（r = -0.586；P < 0.01），与近视矫正量呈显著正相关（r = 0.504；P < 0.01）。向前移位量与术后近视回退程度之间存在显著相关性（r = -0.347；P < 0.05）。
近视PRK和LASIK导致角膜显著向前移位，但并非真正的角膜扩张。角膜较薄且近视度数较高、需要更大切削量的眼更容易发生角膜前突。PRK术后角膜向前移位持续进展至6个月，但LASIK术后无进展。角膜向前移位可能是术后近视回退的因素之一。
