Miyata Kazunori, Kamiya Kazutaka, Takahashi Tetsuya, Tanabe Tatsuro, Tokunaga Tadatoshi, Amano Shiro, Oshika Tetsuro
Meiwakai Medical Foundation, Miyata Eye Hospital, Miyazaki, Japan.
Arch Ophthalmol. 2002 Jul;120(7):896-900. doi: 10.1001/archopht.120.7.896.
Excimer laser refractive surgery has been reported to induce forward shift of the cornea, but its long-term sequelae remain unknown.
To prospectively investigate the time course of changes in corneal elevation after excimer laser photorefractive keratectomy (PRK).
We performed PRK on 65 eyes of 34 patients with refractive errors of -1.25 to -10.0 diopters. The anterior/posterior corneal elevation and corneal thickness were measured with a scanning-slit corneal topography system before and 1 week and 1, 3, 6, and 12 months after surgery. Twenty eyes of 10 healthy control subjects underwent similar measurements at 3-month intervals.
The posterior corneal surface displayed a mean +/- SD forward shift of 36.6 +/- 25.3 microm 1 week after PRK, which gradually increased to 55.1 +/- 46.1 microm at 1 year. All postoperative values were significantly larger than those of healthy controls (2.4 +/- 8.9 microm; P<.001, Mann-Whitney test). The largest forward shift occurred within the first postoperative week. The progression thereafter was most pronounced from 1 to 6 months, and nearly stabilized at 6 months. The variance of postoperative data was statistically significant (P<.001, repeated-measures analysis of variance). Multiple postoperative comparisons demonstrated significant differences between measurements at 1 week and 6 months (P =.002, Tukey Honestly Significant Difference), at 1 week and 1 year (P<.001), at 1 and 6 months (P<.001), and at 1 month and 1 year (P<.001). Progression of forward shift was more prominent in eyes with less preoperative corneal thickness and greater myopia that required larger laser ablation. We observed no progressive thinning and expansion of the cornea during the 1-year follow-up, which refuted the occurrence of true ectasia. A statistically significant correlation was found between the amount of myopic regression and the forward shift of the cornea (Pearson correlation coefficient, r = -0.37; P =.005).
Photorefreactive keratectomy induced forward shift of the cornea, which is not true corneal ectasia. The largest forward shift occurred within the first postoperative week. Changes were progressive up to 6 months postoperatively, but became almost stable thereafter. Eyes with thinner cornea and higher myopia, requiring greater photoablation, are more predisposed to progression. Forward shift of both corneal surfaces added to the tendency toward myopic regression after PRK.
据报道，准分子激光屈光手术可导致角膜向前移位，但其长期后遗症尚不清楚。
前瞻性研究准分子激光屈光性角膜切削术（PRK）后角膜高度变化的时间进程。
我们对34例屈光不正度数在-1.25至-10.0屈光度之间的患者的65只眼进行了PRK。在手术前以及术后1周、1、3、6和12个月，使用扫描裂隙角膜地形图系统测量角膜前/后表面高度和角膜厚度。10名健康对照者的20只眼每隔3个月进行类似测量。
PRK术后1周，角膜后表面平均向前移位36.6±25.3μm（均值±标准差），至1年时逐渐增加至55.1±46.1μm。所有术后测量值均显著大于健康对照者（2.4±8.9μm；Mann-Whitney检验，P<0.001）。最大的向前移位发生在术后第一周。此后，移位进展在1至6个月最为明显，6个月时几乎稳定。术后数据的方差具有统计学意义（重复测量方差分析，P<0.001）。多次术后比较显示，1周与6个月（P = 0.002，Tukey真实显著性差异检验）、1周与1年（P<0.001）、1个月与6个月（P<0.001）以及1个月与1年（P<0.001）的测量值之间存在显著差异。术前角膜厚度较薄且近视度数较高、需要更大激光消融量的眼，向前移位进展更明显。在1年随访期间，我们未观察到角膜的渐进性变薄和扩张，这排除了真正的角膜扩张的发生。近视回退量与角膜向前移位之间存在统计学显著相关性（Pearson相关系数，r = -0.37；P = 0.005）。
屈光性角膜切削术导致角膜向前移位，但并非真正的角膜扩张。最大的向前移位发生在术后第一周。术后变化在6个月内呈进行性，但此后几乎稳定。角膜较薄和近视度数较高、需要更大光消融量的眼更容易发生移位进展。PRK后角膜前后表面的向前移位增加了近视回退的趋势。
