屈光不正少儿角膜前表面的非球面性特征

目的研究近视眼、远视眼少儿角膜前表面的非球面性特征。方法 164例(291眼)经睫状肌麻痹下综合验光仪确定屈光不正度和散光轴向;按等效球镜度分为近视眼组、正视眼组、远视眼组;Humphrey角膜地形图仪检查角膜前表面不同位置曲率值与形状系数(SF)。结果三组SF值近视眼组最低、远视眼组最高,直径7mm处角膜曲率值近视眼较远视眼正视眼都高;角膜形状系数(SF)与球镜度存在有统计学意义的弱正相关 (r=0．16 P=0．003);角膜中央到周边曲率与等效球镜度的回归系数逐渐增加。结论随着近视度数加深,角膜向着周边变平坦的趋势减慢,主要是由于周边直径7mm处变陡速率比中央区快。远视眼角膜向着周边变平坦的趋势加快,可能是由于直径7mm外周边角膜变平坦。

The aspherity characteristics of corneal anterior surface in ametropia children

Objective to investigate the aspherity characteristics of corneal anterior surface in myopic and hyperopia children. Methods Using computerized videokeratography (Humphrey ALTAS Corneal Topography System), the topographic parameters in 291 eyes of 164 nomal children were analyzed, which included the shape factor (SF) , the average power of zone of apex, 3mm, 5mm, 7mm in diameter. Refraction was measured with phoroptor with cycloplegia. The relations between the shape factor (SF) and refractive error, the corneal power and the refractive error were analyzed. Results The SF of the children with myopia was lower a little,The SF of the children with hyperopia was higher a little. The average power of zone of 7mm of the children with myopia was higher than hyperopia or emmetropia. A little but statistically significant positive correlation was found between corneal shape factor (SF) and spherical equivalent refractive error (r=0.16 P=0.003). The regression coefficient between corneal power and the refractive error increased from apex to peripheral area. Conclusions A tendency for cornea to flatten less rapidly in the periphery with increasing myopia or decreasing hyperopia was shown.