Loukotová V, Vlková E, Horácková M, Tokosová E, Pirnerová L, Hlinomazová Z, Dvoráková D, Nĕmec J
Ocní klinika LF MU, FN Brno.
Cesk Slov Oftalmol. 2009 Oct;65(5):176-81.
The aim of the prospective study was to evaluate higher order aberrations and contrast sensitivity after photorefractive keratectomy (PRK) using the standard photoablation profile.
The group consisted of 37 patients (69 eyes), the mean age 27.2 +/- 4.5 years, who underwent PRK with target emetropia during the period January 2007 -December 2007. In 19 cases, it was correction of myopia, in 50 cases myopia with astigmatism.The preoperative spherical equivalent was -3.14 +/- 0.95 D. The PRK was performed by means of excimer laser system Technolas 217 (Bausch & Lomb) with the standard phoptoablation profile (PlanoScan 2000), using the 6.5 mm optical zone. The visual acuity, contrast sensitivity (CS; CSV-1000E, VectorVision) under mesopic circumstances and monochromatic aberrations (Zywave, Bausch & Lomb) were evaluated before the surgery, and 1,3, 6, and 12 months thereafter. The pair t-test, Wilcoxon test, and the Mann - Whitney U test (alpha = 0.05) were used for the statistical analysis.
The PRK showed high index of effectiveness and safety (0.98, respectively 1.03 in the first year after the procedure). The contrast sensitivity under mesopic circumstances was not significantly involved after the PRK. The main value of the CS remained during the whole follow-up period within the physiological range in all spatial frequencies. Postoperatively, the part of spherical aberration on the higher order aberrations increased from 13.1% preoperatively to 16.6% one year after the PRK. In one half of the cases, the change of the higher order aberrations was within the range +/- 0.1 microm. In 66% of cases, the change of the spherical aberration was +/- 0.05 microm. The higher order aberrations comparing to the preoperative values decreased or remained unchanged approximately in one third of the cases, and the spherical aberration in one quarter of the cases. There was not established dependence between monochromatic aberrations values and the contrast sensitivity.
Although the conventional RPK for low myopia treatment induces higher order aberrations including the spherical aberration, the impact on the contrast sensitivity under mesopic circumstances in our group were not significant. The contrast sensitivity of the most of patients was near the upper limit of the normal range.
这项前瞻性研究的目的是评估使用标准光消融模式的准分子激光原位角膜磨镶术（PRK）后高阶像差和对比敏感度。
该组由37例患者（69只眼）组成，平均年龄27.2±4.5岁，于2007年1月至2007年12月期间接受以正视化为目标的PRK手术。其中19例为近视矫正，50例为近视合并散光。术前等效球镜度为-3.14±0.95D。PRK使用Technolas 217准分子激光系统（博士伦公司），采用标准光消融模式（PlanoScan 2000），光学区直径6.5mm。在手术前、术后1、3、6和12个月评估视力、中暗环境下的对比敏感度（CS；CSV-1000E，VectorVision公司）和单色像差（Zywave，博士伦公司）。采用配对t检验、Wilcoxon检验和Mann-Whitney U检验（α=0.05）进行统计分析。
PRK显示出高有效性和安全性指标（术后第一年分别为0.98和1.03）。PRK后中暗环境下的对比敏感度无显著变化。在整个随访期间，所有空间频率下CS的主要值均保持在生理范围内。术后，高阶像差中球差的比例从术前的13.1%增加到PRK术后一年的16.6%。在一半的病例中，高阶像差的变化在±0.1微米范围内。在66%的病例中，球差的变化为±0.05微米。与术前值相比，约三分之一病例的高阶像差降低或保持不变，四分之一病例的球差降低或保持不变。单色像差值与对比敏感度之间未发现相关性。
尽管传统的低近视PRK会诱导包括球差在内的高阶像差，但在我们组中，对中暗环境下对比敏感度的影响并不显著。大多数患者的对比敏感度接近正常范围上限。
