Cantera E, Cantera I, Olivieri L
Department of Ophthalmology, II University of Rome Tor Vergata, Italy.
Refract Corneal Surg. 1993 Mar-Apr;9(2 Suppl):S19-22.
Videokeratography is a useful method for postoperative evaluation of photorefractive keratectomy (PRK). The aim of this study was to evaluate the percentage of decentration, the relationship between decentration relative to the corneal apex, postoperative astigmatism, and the relationship between decentration and best corrected Snellen visual acuity. Using the TMS-1 videokeratoscope we analyzed the corneal topography of 175 myopic eyes treated with PRKs ranging between -1.30 D and -15.90 D, performed using the Summit UV200 193-nanometer excimer laser, before and at least 6 months after the procedure. Concerning centration, 122 eyes (75%) were centered within 0.5 mm and 53 eyes (30.3%) were decentered more than 0.5 mm, with nine eyes (5.1%) being decentered more than 1 mm. There was a correlation between best spectacle corrected visual acuity and the amount of decentration. The higher attempted corrections showed greater amounts of decentration. Postoperative induced astigmatism was greater in the group with the highest decentration (1.81 +/- 2.64 D) than in the one with lower decentration (0.09 +/- 0.50 D). The most severe complication induced by a decentered PRK is an increase of postoperative astigmatism.
角膜地形图是评估准分子激光原位角膜磨镶术（PRK）术后效果的一种有用方法。本研究的目的是评估偏心百分比、相对于角膜顶点的偏心与术后散光之间的关系，以及偏心与最佳矫正视力之间的关系。使用TMS-1角膜地形图仪，我们分析了175只近视眼睛的角膜地形图，这些眼睛接受了屈光度在-1.30 D至-15.90 D之间的PRK治疗，使用Summit UV200 193纳米准分子激光进行手术，分别在手术前和术后至少6个月进行测量。关于中心定位，122只眼睛（75%）的中心偏移在0.5毫米以内，53只眼睛（30.3%）的中心偏移超过0.5毫米，9只眼睛（5.1%）的中心偏移超过1毫米。最佳矫正视力与偏心量之间存在相关性。较高的预期矫正度数显示出更大的偏心量。偏心程度最高的组术后诱导散光（1.81±2.64 D）大于偏心程度较低的组（0.09±0.50 D）。PRK偏心导致的最严重并发症是术后散光增加。
