聚焦“激光近视矫正手术安全性”之争

专家观点：术后远期视力下降与近视本身有关。 准分子激光近视矫正手术迄今已有20多年的历史了。我国自1993年开展至今．并没有发现“术后十余年出现不明原因视力明显下降”的情况．     

人工晶状体计算公式比较

目的 以临床资料验证比较SRK－Ⅱ公式、SRK／T公式和SCDK公式的准确性。方法 选择380只老年性白内障眼,术后3个月以上测量眼轴长度、角膜屈光度、眼屈光度,将测量值分别代入3个公式计算平均绝对屈光误差值,比较3个公式的准确性。结果 在眼轴长度小于26mm时,3个公式计算的平均绝对屈光误差值相差不大。眼轴长度大于26mm时,SRK－II公式的平均绝对屈光误差值为1．42D,SRK／T公式误差值为0．84D,SCDK公式误差值为0．89D;屈光误差值大于2D者,SRK－II公式为15．53％,SRK／T公式为4．74％,SCDK公式为5．26％。结论 在眼轴长度大于26mm时,SCDK和SRK／T公式准确性明显高于SRK－Ⅱ公式,SCDK和SRK／T公式的准确性相差不大,均高于SRK－Ⅱ公式。     

注入式人工晶体的研究进展

白内障术后人工晶体的植入已成为白内障复明的主要方法，目前广泛应用的人工晶体因缺乏调节作用，术后不能同时获得满意的远、近视力。注入式人工晶体因具有和正常晶体相同的调节作用而受到越来越广泛的重视，虽然目前仍处于动物实验阶段，但已获得的进展令人鼓舞。本文综述了注入式人工晶体的手术技术、注入材料、调节力、术后并发症以及目前存在的主要问题。     

中低度近视LASEK术后角膜地形图分析

目的　探讨中低度近视准分子激光上皮瓣下角膜磨镶术 (LASEK)后的角膜地形图变化。方法　中低度近视LASEK术 40例 (80眼 ) ,术前及术后 1、3、6月行角膜地形图检查 ,与综合验光结果进行相关分析。结果　LASEK术后 6月裸眼视力≥ 0 .6者占 10 0 .0 0 % ,其中≥ 1.0者占 97.5 0 %。 80眼术前角膜地形图表现最多者为对称领结形 ,依次为非对称领结形 ,圆形 ,椭圆形及不规则形。术后 6月检查时角膜地形图主要表现为圆形或椭圆形 (75 .0 0 % ) ,肾形 (2 1.2 5 % )及半环形 (3 .75 % )。LASEK术后 (SAI)、SimK等效值和SimK的差值较术前变化显著 (P <0 .0 5 ) ,SRI改变则不显著。结论　LASEK治疗中低度近视疗效佳。角膜地形图的定量分析对术后角膜表面球面性状的评价、手术设计的改进和疗效的预测具有重要意义。     

正常角膜及圆锥角膜的生物力学特性比较研究

Objective To compare the corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer (ORA) in normal and keratoconic eyes. Methods It was a case-control study. Random selected 96 normal eyes and 46 keratoconic eyes in the same period were included in this study. Normal eyes were divided into 2 groups: high corneal astigmatism (≥3.00 D) and low-to-moderate corneal astigmatism (<3.00 D). Keratoconic eyes were also divided into 3 groups based on Amsler-Krumeich classification: mild (stage Ⅰ), moderate (stage Ⅱ) and severe (stage Ⅲ/Ⅳ). CH and CRF were compared between groups and the areas under ROC curves of the CH and CRF were calculated. Results The mean CH and CRF were (7.1±1.6) mm Hg and (6.3±1.5) mm Hg in keratoconic eyes compared with (10.1±1.3) mm Hg and (10.5±1.6) mm Hg in normal eyes. The difference were statistically significant(t=-11.813, -14.943 ;P<0.001). In normal eyes, there was no difference of CH or CRF between the high corneal astigmatism and low-to- moderate corneal astigmatism (t=0.373,0.095; P>0.05). In keratoconic eyes, there was a significant negative correlation between CH and the keratoconus grade (r=-0.627, P<0.001) and the same relationship was found between CRF and the keratoconus grade (r=-0.587, P<0.001). In multiple linear regression analysis, CH was correlated with central corneal thickness (CCT) and corneal curvature (r=0.320, -0.375;P<0.05) and CRF was correlated with corneal curvature in keratoconic eyes (r=-0.441 ,P<0.01), while they were only correlated with CCT in normal eyes (r=0.367,0.459;P<0.001). The areas under ROC curves of the CH and CRF were 0.9282 and 0.9731 (Z=20.462,38.305 ;P<0.0001), the difference between them was significant (Z =7.134,P=0.008). Conclusions The CH and CRF were significantly lower in keratoconic eyes than in normal eyes, especially on CRF. The long-term follow-up of CH and CRF may provide information for evaluation of progression of keratoconus. They may be included as indicators for detecting keratoconus.     

准分子激光上皮下角膜磨镶术中应用丝裂霉素C对角膜内皮及后表面的影响

目的探讨准分子激光上皮下角膜磨镶术（LASEK）术中应用0.02%丝裂霉素C（MMC）对角膜内皮及后表面的影响。方法前瞻性连续性双盲病例研究。在复旦大学附属眼耳鼻喉科医院行LASEK手术的连续病例33例（66眼）,随机选择一眼,在准分子激光切削后在基质床面留置0.02% MMC棉片20 s,另一眼不应用MMC;对比患者术后3、6个月中央角膜内皮细胞计数、变异系数以及角膜后表面前移量。采用配对t检验进行统计学分析。结果术后3、6个月MMC应用眼的内皮细胞密度分别为（3353.3±290.3）个/mm2、（3407.6±298.4）个/mm2;变异系数分别为（13.36±6.29）%、（13.48±4.34）%;对照眼相应时间段的内皮细胞密度分别为（3258.7±284.6）个/mm2、（3339.2±213.4）个/mm2;变异系数分别为（14.52±7.85）%、（14.06±6.50）%,各参数差异均无统计学意义。术后3、6个月MMC应用眼的角膜后表面前移量分别为（-0.67±2.26）μm、（-0.52±2.67）μm;角膜后表面曲率改变分别为（0.01±0.20）D、（0.01±0.21）D;对照眼相应时间段的角膜后表面前移量分别为（-0.85±2.31）μm、（-0.15±3.00）μm;角膜后表面曲率改变分别为（-0.01±0.22）D、（0.05±0.17）D,差异均无统计学意义。结论LASEK术中使用0.02% MMC对角膜内皮细胞密度、变异系数、角膜后表面高度等无明显影响,安全性较高。     

正常角膜及圆锥角膜的生物力学特性比较研究

Objective To compare the corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer (ORA) in normal and keratoconic eyes. Methods It was a case-control study. Random selected 96 normal eyes and 46 keratoconic eyes in the same period were included in this study. Normal eyes were divided into 2 groups: high corneal astigmatism (≥3.00 D) and low-to-moderate corneal astigmatism (<3.00 D). Keratoconic eyes were also divided into 3 groups based on Amsler-Krumeich classification: mild (stage Ⅰ), moderate (stage Ⅱ) and severe (stage Ⅲ/Ⅳ). CH and CRF were compared between groups and the areas under ROC curves of the CH and CRF were calculated. Results The mean CH and CRF were (7.1±1.6) mm Hg and (6.3±1.5) mm Hg in keratoconic eyes compared with (10.1±1.3) mm Hg and (10.5±1.6) mm Hg in normal eyes. The difference were statistically significant(t=-11.813, -14.943 ;P<0.001). In normal eyes, there was no difference of CH or CRF between the high corneal astigmatism and low-to- moderate corneal astigmatism (t=0.373,0.095; P>0.05). In keratoconic eyes, there was a significant negative correlation between CH and the keratoconus grade (r=-0.627, P<0.001) and the same relationship was found between CRF and the keratoconus grade (r=-0.587, P<0.001). In multiple linear regression analysis, CH was correlated with central corneal thickness (CCT) and corneal curvature (r=0.320, -0.375;P<0.05) and CRF was correlated with corneal curvature in keratoconic eyes (r=-0.441 ,P<0.01), while they were only correlated with CCT in normal eyes (r=0.367,0.459;P<0.001). The areas under ROC curves of the CH and CRF were 0.9282 and 0.9731 (Z=20.462,38.305 ;P<0.0001), the difference between them was significant (Z =7.134,P=0.008). Conclusions The CH and CRF were significantly lower in keratoconic eyes than in normal eyes, especially on CRF. The long-term follow-up of CH and CRF may provide information for evaluation of progression of keratoconus. They may be included as indicators for detecting keratoconus.     

角膜伤口愈合机制对准分子激光角膜屈光手术的启示

角膜伤口愈合反应是由细胞因子、生长因子、趋化因子介导的复杂级联反应。角膜上皮细胞和基底膜在这一过程中起了重要的作用,而这二者在准分子激光角膜屈光手术中常常被损伤。因此,深刻理解角膜伤口愈合过程以及并发症产生的原因,对提高准分子激光角膜屈光手术的有效性和安全性具有重要意义。就角膜伤口愈合过程及其机制进行综述。