准分子激光屈光性角膜切削术后10年角膜内皮细胞的观察

Evaluation of corneal endothelial cells ten years after photorefractive keratectomy

目的评价和了解准分子激光屈光性角膜切削术（PRK）对角膜内皮细胞密度和形态的远期影响，并探究其与切削深度、激光扫描时间等手术参数的相关性。方法回顾性病例研究。PRK术后10年患者24例（44眼）：随机选取未接受过眼科手术的正常眼作为对照组，共25例（45眼）。应用非接触角膜内皮镜测量角膜中央内皮细胞密度和形态。利用Pearson线性相关分析研究PRK术后10年组内皮细胞密度和形态与手术参数间的相关性。另将PRK术后10年患者按切削量大小分为低切削（〈60um）、中切削（60。90pum）和高切削（〉90um）3组，并对比分析此3组及对照组间角膜中央内皮细胞密度和形态的差异。采用独立样本t检验、Pearson相关分析、单因素方差分析进行数据处理。结果PRK术后10年组与对照组间平均内皮细胞面积、内皮细胞密度、内皮细胞面积变异系数、六边形内皮细胞百分比的差异均无统计学意义（t=-1．390、1．323、0．569、0．788，P〉0．05）。平均内皮细胞面积和内皮细胞密度与等效球镜度间具有明显相关性（r=-0．424、0．420，P〈0．01），同时该两参数与准分子预切削深度间亦显示具有相关关系（r=0．391、一0．388，P〈0．01）。PRK术后低、中、高切削组与对照组间平均内皮细胞面积、内皮细胞密度、内皮细胞面积变异系数、六边形内皮细胞百分比的差异均无统计学意义（F=2．195、1．961、0．817、1．529，P〉0．05）。结论PRK术后远期角膜中央内皮细胞密度及形态无明显异常改变。等效球镜度及预切削深度会影响平均内皮细胞面积和内皮细胞密度。

Objective To evaluate and determine the long-term effects of photorefractive keratectomy （PRK） on corneal endothelial cell density and morphology, and investigate their correlation with surgically designed parameters such as ablation depth and laser scan time. Methods In this retrospective study, 24 patients （44 eyes） who underwent PRK 10 years earlier and 45 normal eyes of 25 cases without any ophthalmologic surgery were enrolled in this study as the PRK group and the control group, respectively. Noncontact specular microscopy （Topcon, SP3000P, Japan） was used to measure central corneal endothelial cell density and morphology. A Pearson correlation was used to analyze the relationship between corneal endothelial cell density and morphology, and surgically designed parameters. The PRK group was divided into 3 subgroups based on the depth of tissue ablation： low ablation group （ablation depth 〈60 p,m）, moderate ablation group （ablation depth： 60-90 Ixm） and high ablation group （ablation depth 〉90 Ixm）. The differences in corneal endothelial cell density and morphology between these 3 groups and the control group were analyzed. Data were analyzed using independent samples t test, Pearson correlation, ANOVA. Results The differences in average endothelial cell area, endothelial cell density, coefficient of variation of the endothelial cell area and percentage of hexagonal cells between the PRK group and control group were not statistically significant （t=-1.390, 1.323, 0.569, 0.788, P〉0.05）. However, there were statistically significant correlations between average endothelial cell area and endothelial cell density and manifest refraction spherical equivalent （MRSE） （r=-0.g2g, 0.420, P〈0.01）. The 2 parameters were also significantly correlated with attempted ablation depth （r=0.391, -0.358, P〈0.01）. The differences in average endothelial cell area, endothelial cell density, coefficient of variation of the endothelial cell area and percentage of hexagonal ceils between the low ablation group, moderate ablation group, high ablation group and control group were not statistically significant （F=2.195, 1.961, 0.817, 1.529, P〉0.05）. Conclusion Compared to normal eyes, no significantly abnormal change in central corneal endothelial cell density or morphology was observed 10 years after PRK. MRSE and attempted ablation depth may have an effect on the average endothelial cell area and endothelial cell density.