准分子激光原位角膜磨镶术后角膜后表面屈光力变化

Changes of posterior corneal power after myopic laser in situ keratomileusis

目的 探讨准分子激光原位角膜磨镶术(LASIK)后角膜后表面屈光力变化对角膜总屈光力的影响及其在术后屈光回退中所起的作用;分析角膜后表面屈光力变化的相关因素。 方法 对47例89眼施行LASIK,其中49眼高度近视,40眼中低度近视。术前与术后1个月,应用裂隙扫描角膜地形网检测角膜前后表面屈光力及隆起度。分析角膜后表面屈光力及角膜后表面隆起度变化的相关因素。 结果LASIK术后.角膜后表面屈光力与角膜后表面隆起度的改变均具有统计学意义(-6.64±0.23)D/(-7.19±O.28)D,P<0.05;(24.57±10.74)μm/(56.98±15.60)μm,P<O.05,两者均与屈光角膜平面等效球镜度改变量之间有相关关系(R=O.23,P=0.032;R=O.25,P=O.02)。高度近视组角膜后表面屈光力与角膜后表面隆起度改变量大于中低度近视组的改变量(P<0.05)。 结论 LASIK术后,角膜后表面屈光力与角膜后表面隆起度增加;两者变化程度与近视矫正程度相关。LASIK术后近视回退与角膜后表面前凸有关。

Objective To investigate the effect of changes of posterior corneal power on total corneal power after laser in situ keratomileusis (LASIK) ,and analyze the relevant factors to the changes of posterior corneal power. Method 89 eyes of 47 consecutive LASIK subjects were observed in corneal plane,including 49 eyes with high myopia( - 7. 78±1. 19D) and 40 eyes with mild-moderate myopia ( - 5. 19 ±0.67 D). Orbsoan corneal topography system was used preoperatively and 1 month postoperatively, respectively. Factors affecting the posterior corneal power and posterior surface elevation after LASIK were analyzed. Results Changes of posterior corneal power and posterior surface elevation ( - 6. 64 ?0. 23 D/- 7. 19 ±0. 28 D ,P <0. 05) ; (24. 57±10. 74 μm/56. 98±15. 60μm,P <0. 05) were statistically significant. The changes of posterior corneal power and posterior surface elevation correlated significantly with the A SEQ ( R = 0. 23 , P = 0. 032 ; R = 0. 25 ; P = 0. 02 ). The changes of posterior corneal power and posterior surface elevation in high myopia were significantly more than those of mild-moderate myopia after LASIK ( P < 0. 05 ). Conclusions The changes of posterior corneal power and posterior surface elevation correlate significantly with the△SEQ. Increased negative posterior corneal power and posterior surface elevation indicate that mild forward shift of posterior corneal surface is common after LASIK and it may be one of causes of refractive regression after LASIK.