【摘要】 目的：分别测量近视眼及白内障两组患者角膜前表面非球性系数 (Q值)，探讨可能的相关因素。方法：近视眼患者240例，按屈光度分为高、中、低三组，性别比例基本匹配，年龄为18~32岁，随机选择其中48例配戴角膜接触镜的患者分别测量摘镜后第1,15d的Q值；白内障患者123例，年龄42～80岁。常规进行角膜地形图、综合验光、角膜中央厚度等检查，对各项检查结果进行分析。结果：近视眼组其Q值范围为0.62～0.04，平均为0.296；白内障组其Q值范围为0.67～0.01，平均为0.232，白内障患者的Q值低于近视眼患者的Q值，差异有统计学意义 (P＝0.00)；近视眼的Q值女性高于男性，差异有统计学意义 (P＝0.00)；Q值与屈光度相关性分析显示无明显相关，高、中、低三组间差异没有统计学意义；近视眼组同一个体左右眼Q值、隐形眼镜脱镜后第1,15d Q值分布线性关系显著，但差异均无统计学意义。结论：Q值是表示角膜最平坦子午线角膜变陡或变平的程度表面形状系数。近视眼及白内障患者两个群体角膜Q值均呈正态分布，两组数值分布差异有统计学意义；Q值与角膜曲率、屈光度、角膜厚度无明显相关，配戴角膜接触镜对Q值的测量结果无影响。
【关键词】 近视眼;白内障;角膜非球面性;角膜曲率;屈光度;角膜厚度
Analysis of measurement results of anterior corneal asphericity of different groups
YiJing Xin, LiFen Wu, Min Lü, JingYi Zhuang
Department of Ophthalmology, Xiamen the First Hospital Affiliated of Fujian Medical University, Xiamen 361003, Fujian Province, China
Correspondence to: YiJing Xin. Department of Ophthalmology, Xiamen the First Hospital Affiliated of Fujian Medical University, Xiamen 361003, Fujian Province, China. [email protected]
AbstractAIM: To explore some possible relative factors through measuring the anterior corneal asphericity factor Q in cataract and myopic eyes respectively.METHODS: A total of 240 myopia cases aged 1832 with an idea sex ratio, were divided into high, moderate and low groups. Also 48 corneal contact lens (CCL) wearers were randomly chosen from myopia group, Their 1st and 15th days Q value were measured after taking off lens. Totally 123 cases aged 4280 were included in cataract group. Both myopia and cataract groups were received some routine check like corneal topography, subject refraction and central corneal thickness measurement and the results were analyzed.RESULTS: Q value was 0.62～0.04 with an average value of 0.296 in myopia group and 0.67～0.01 with an average value of 0.232 in cataract group. Q value of senile cataract was lower than that of the myopia, the difference showed statistical significance (P=0.00). Females Q value was higher than males, which showed statistical significance (P=0.00). No significant linear correlation was found between Q value and diopter, and the difference among the three groups had no statistical significance. There was no statistical difference between 2 eyes of each subject from myopia group and the Q value of their 1st and 15th day after taking off CCL, though the two values indicated significant linear correlation.CONCLUSION: Q value is a shape factor to indicate the degree of steepness of the flattest meridians on corneal surface. Both Q values in myopia and in cataract group show normal distribution. And the distribution difference between the two groups had statistical significance. Q value has no correlation with cornea curvature, diopter and cornea thickness. CCL wearing is no interference to the results.
KEYWORDS: myopia; cataract; anterior corneal asphericity; cornea curvature; diopter; cornea thickness
0引言
Q值是表示角膜表面形状的系数，可以描述角膜非球面的特征，可能受一些参数的影响，改变其数值的眼部手术或治疗会引起人眼的成像差异，正确理解和认识Q值有助于提高与光学有关的临床治疗效果。
1对象和方法
1.1对象
随机选取200610/200704在我科进行准分子激光和白内障超声乳化手术的患者进行分组研究，近视组年龄18～32(平均23.6)岁，等效球镜 0.75～13.75D，按等效球镜分3组：低度近视 (0.75～3.00D)，中度近视 (3.25～6.00 D)，重度近视 (＞6.25D)；白内障组年龄42～80岁，裸眼视力均低于0.3；近视眼组中48例配戴角膜接触镜患者分别测量摘镜后第1,15d的Q值；近视眼组患者符合准分子激光手术条件，白内障组患者拟行白内障超声乳化＋人工晶状体植入手术；所有患者无角膜手术史，球结膜无翼状胬肉等增生性疾病。
1.2方法
1.2.1角膜Q值的测量
检测仪器为Allegretto角膜地形图仪，方法(略)，重复测量3次以上，所获取的图像尽量达到70%以上的角膜表面积；白内障组因患者皮肤松驰和上眼睑遮盖角膜等原因，部分仅测量60%以上角膜表面积。根据曲率线性变化一致性、各经线离心率e相同、方向相近、主要经线的K值和轴位基本一致等参数判断重复性。通过公式Q＝ e2计算Q值。
1.2.2其它数据的检测
散瞳后进行验光，验光仪为TOPCON KR7100；角膜厚度采用A超 (NIDEK UP1000)测量；角膜曲率在角膜地形图上直接读取。
统计学处理：用SPSS 15.0统计软件，采用pearson相关分析、配对样本t检验(pairedsamples t test)、单因素方差分析、独立样本t检验 (independentsamples t test)等方法进行分析。
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