Dam-Johansen M, Olsen T
Department of Ophthalmology, Arhus University Hospital, Aarhus C, Denmark.
Acta Ophthalmol Scand. 1997 Dec;75(6):669-74. doi: 10.1111/j.1600-0420.1997.tb00628.x.
To study the surgically induced astigmatism after phacoemulsification through either a 4 or a 6 mm scleral tunnel incision by using multiple analyses of astigmatism.
197 eyes from 186 patients scheduled for phacoemulsification between October 1992 and March 1994 were randomly assigned two different-sized incisions with follow-ups at 1 day, 1 week, 2 weeks, 1 month and 4 months after surgery. The surgically induced astigmatism was evaluated using at each follow-up: 1) The subtraction method, 2) vector analysis, 3) vector decomposition, 4) Cravy's vertical vector, 5) Naeser's polar values, and 6) the algebraic method.
By subtraction, without regard to axis, the induced astigmatism 4 months after surgery was +0.04 D and +0.18 D in the 4 mm and the 6 mm incision group, respectively. By vector analysis, the numerical value of the induced cylinder was stable one month after surgery at 0.61 D and 0.77 D in the 4 mm and in the 6 mm group, respectively. However, cylinder orientation was not found stable until 4 months after surgery, where 94% and 96% of the surgically induced astigmatism (vector decomposition) was against-the-wound in the two groups, respectively. By Cravy's method, the mean induced astigmatism changed from -0.08 D to -0.32 D and from -0.42 D to -0.60 D between 1 and 4 months in the 4 mm and the 6 mm group, respectively. Similar values were found with Naeser's method and with the algebraic method.
We conclude the mean cylinder of the surgically induced astigmatism (vector analysis) to be stable 1 month after phacoemulsification with both the 4 mm and 6 mm scleral tunnel incision. However, the direction of the induced axis (vector decomposition) was still drifting between 1 and 4 months in both groups. These astigmatic changes were adequately described using vector analysis and vector decomposition.
通过对散光的多种分析方法，研究白内障超声乳化术后经4mm或6mm巩膜隧道切口引起的手术性散光。
1992年10月至1994年3月期间计划行白内障超声乳化术的186例患者的197只眼被随机分配到两种不同大小的切口组，并在术后1天、1周、2周、1个月和4个月进行随访。在每次随访时使用以下方法评估手术性散光：1）减法法，2）矢量分析，3）矢量分解，4）克拉维垂直矢量法，5）内泽尔极坐标值法，6）代数法。
采用减法法，不考虑轴位，术后4个月4mm切口组和6mm切口组的诱导散光分别为+0.04D和+0.18D。通过矢量分析，术后1个月时4mm组和6mm组诱导柱镜的数值分别稳定在0.61D和0.77D。然而，直到术后4个月柱镜轴位才稳定，两组中分别有94%和96%的手术性散光（矢量分解）与切口方向相反。采用克拉维法，4mm组和6mm组在1至4个月期间平均诱导散光分别从-0.08D变为-0.32D和从-0.42D变为-0.60D。在内泽尔法和代数法中也发现了类似的值。
我们得出结论，白内障超声乳化术后，采用4mm和6mm巩膜隧道切口，手术性散光（矢量分析）的平均柱镜在1个月时稳定。然而，两组在1至4个月期间诱导轴位（矢量分解）仍在漂移。使用矢量分析和矢量分解可以充分描述这些散光变化。
