Pavlopoulos G P, Horn J, Feldman S T
Department of Ophthalmology, University of California, San Diego School of Medicine, La Jolla, USA.
Am J Ophthalmol. 1995 Jun;119(6):712-22. doi: 10.1016/s0002-9394(14)72775-8.
To examine the effect of adding artificial tears for one minute to normal eyes and eyes that have undergone keratoplasty by using computer-assisted videokeratography.
We prospectively analyzed 24 normal corneas (24 patients) chosen by random number table (reproducibility section [10 eyes], tear section [14 eyes]) as well as 14 postkeratoplasty corneas. The parametric descriptors analyzed statistically included the simulated keratometry value, surface asymmetry index, surface regularity index, power at the vertex normal, and the pupil offsets from the visual axis. Vectoral analysis was used to calculate the difference in power and axis between the simulated keratometry values before and after tear instillation.
In normal eyes, tear instillation increased the surface asymmetry index (0.28 +/- 0.34, P = .01), changed the simulated keratometry value (0.23 diopter by 27.8 degrees), and power (0.79 +/- 0.82 diopters, P = .004) and location (0.91 +/- 0.76 mm) of the steepest point of the cornea changed. In postkeratoplasty eyes, the surface regularity index decreased (0.49 +/- 0.80, P = .04), surface asymmetry index decreased (0.37 +/- 1.03, P = .21), mean simulated keratometry value changed (1.04 diopters by 1.01 degrees), and power (0.70 +/- 2.34 diopters, P = .28) and location (1.04 +/- 1.17 mm) of the steepest point of the cornea changed. Changes were greater than the variability of the surface regularity index (0.07 +/- 0.05), surface asymmetry index (0.04 +/- 0.03), simulated keratometry value power (0.08 +/- 0.06 diopter), and axis (4.6 +/- 5 degrees).
The addition of artificial tears to normal or regular and symmetric eyes that have undergone keratoplasty worsened symmetry and changed the power and location of the steepest point. However, the addition of artificial tears to irregular eyes that have undergone penetrating keratoplasty created a more regular and symmetric surface and significantly altered the simulated keratometry values. We recommend that corneal topography be performed before the application of artificial tears.
通过计算机辅助角膜地形图检查，研究向正常眼和角膜移植术后眼滴注一分钟人工泪液的效果。
我们前瞻性分析了通过随机数字表选取的24只正常角膜（24例患者）（重复性部分[10只眼]，泪液部分[14只眼]）以及14只角膜移植术后的角膜。统计学分析的参数描述符包括模拟角膜曲率计值、表面不对称指数、表面规则性指数、顶点法线处的屈光力以及瞳孔相对于视轴的偏移。采用矢量分析计算滴注泪液前后模拟角膜曲率计值在屈光力和轴向上的差异。
在正常眼中，滴注泪液增加了表面不对称指数（0.28±0.34，P = 0.01），改变了模拟角膜曲率计值（27.8度时为0.23屈光度），角膜最陡点的屈光力（0.79±0.82屈光度，P = 0.004）和位置（0.91±0.76毫米）发生了变化。在角膜移植术后眼中，表面规则性指数降低（0.49±0.80，P = 0.04），表面不对称指数降低（0.37±1.03，P = 0.21），平均模拟角膜曲率计值改变（1.01度时为1.04屈光度），角膜最陡点的屈光力（0.70±2.34屈光度，P = 0.28）和位置（1.04±1.17毫米）发生了变化。这些变化大于表面规则性指数（0.07±0.05）、表面不对称指数（0.04±0.03）、模拟角膜曲率计值屈光力（0.08±0.06屈光度）和轴（4.6±5度）的变异性。
向正常或规则对称的角膜移植术后眼滴注人工泪液会使对称性变差，并改变最陡点的屈光力和位置。然而，向穿透性角膜移植术后的不规则眼滴注人工泪液可产生更规则对称的表面，并显著改变模拟角膜曲率计值。我们建议在应用人工泪液之前进行角膜地形图检查。
