Lombardo Marco, Lombardo Giuseppe, Manzulli Michele, Serrao Sebastiano
Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Italy.
J Refract Surg. 2006 Feb;22(2):178-86. doi: 10.3928/1081-597X-20060201-17.
To analyze the long-term corneal topographic changes 4 years after myopic photorefractive keratectomy (PRK).
This study comprised 15 patients (30 eyes) who had PRK surgery with a scanning-spot excimer laser (Chiron Technolas 217C; Bausch & Lomb, Dornach, Germany) and were followed up to 4 years after surgery. The eyes were subdivided into three groups according to the preoperative spherical equivalent refraction. Corneal topographic maps were obtained for all eyes with a Placido disc topographer. Preoperative and follow-up topographical data were imported into a custom software program, which computed the average composite corneal maps and difference maps for each study group to quantify the anterior corneal changes following laser ablation. The software delineated three concentric zones of the corneal surface to characterize the regional corneal remodeling following the surgery.
A significant central corneal steepening (approximately 0.25 D, P < .001) was calculated between the 1- and 4-year postoperative maps in all study groups. A significant steepening (P < .001) of the corneal periphery was also noted for the lower myopic ablations whereas a peripheral flattening (P < .001) was observed for the deeper ablations between 1 and 4 years after surgery.
The anterior corneal surface was observed to remodel for up to 4 years after surface ablation, steepening a mean of approximately 0.25 D.
分析近视性准分子原位角膜磨镶术（PRK）4年后角膜地形图的长期变化。
本研究纳入15例患者（30只眼），这些患者接受了扫描光斑准分子激光（Chiron Technolas 217C；德国多纳赫博士伦公司）PRK手术，并在术后随访4年。根据术前等效球镜度将眼睛分为三组。使用Placido盘地形图仪获取所有眼睛的角膜地形图。将术前和随访的地形学数据导入自定义软件程序，该程序计算每个研究组的平均复合角膜地形图和差异图，以量化激光消融后角膜前部的变化。该软件划定了角膜表面的三个同心区域，以描述手术后区域角膜重塑情况。
所有研究组术后1年和4年的地形图之间计算出中央角膜明显变陡（约0.25 D，P <.001）。对于较低度数的近视性消融，还观察到角膜周边明显变陡（P <.001），而在手术后1至4年，对于较深度的消融则观察到周边变平（P <.001）。
表面消融后观察到角膜前表面重塑长达4年，平均变陡约0.25 D。
