Fundación Oftalmológica del Mediterráneo, Facultad de Física, Universidad de Valencia, Burjassot (Valencia), Spain.
J Cataract Refract Surg. 2011 Oct;37(10):1895-901. doi: 10.1016/j.jcrs.2011.04.036. Epub 2011 Aug 23.
To analyze changes in the eye's refractive properties when a toric intraocular lens (IOL) rotates.
Fundación Oftalmológica del Mediterráneo, Valencia, Spain.
Experimental study.
The matrix definition of astigmatism was used in this theoretical study and compared with another vector representation. Two methods were compared: (1) The cylinder, C, resulting from the addition of 2 cylinders C(1) and C(2) whose axes form an angle a, is obtained by the addition of 2 vectors of values C(1) and C(2) forming an angle 2a; (2) the power matrix, F, of a thin astigmatic dioptric system that decomposes naturally into 3 orthogonal components: the purely spherical part F(nes,) the ortho-astigmatism F(or), and oblique astigmatism F(ob).
The residual cylinder was one third of the corneal astigmatism when a toric IOL rotated ±10 degrees when the cylinder values for the cornea (C(1)) and IOL (C(2)) were equal. Nevertheless, in most cases C(1) is greater than C(2); therefore, the residual astigmatism did not change noticeably with small rotations. The angle of rotation, b, which annuls the astigmatism correction, could be obtained from the following: cos(π + 2b) = -r/2, with r being the ratio between the IOL and cornea cylinders.
The 2 methods gave equivalent results. When the IOL cylinder had a value different from that of the corneal astigmatism, a better choice would be a lower, rather than higher, cylinder value to reduce residual astigmatism. In general, toric IOL rotations less than 10 degrees changed the eye's refraction less than 0.50 diopter. Thus, small axis rotations are not an obstacle for satisfactory astigmatism correction with toric IOLs.
No author has a financial or proprietary interest in any material or method mentioned.
分析散光型人工晶状体（IOL）旋转时眼睛屈光性质的变化。
西班牙巴伦西亚地中海眼科基金会。
实验研究。
本理论研究采用了散光的矩阵定义，并与另一种向量表示法进行了比较。比较了两种方法：（1）两个值分别为 C(1)和 C(2)的向量形成的角度为 2a 时，两个柱面 C(1)和 C(2)形成的角度为 a，所得的 C 柱为两个柱面 C(1)和 C(2)的和；（2）薄散光屈光系统的功率矩阵 F 自然分解为 3 个正交分量：纯粹的球镜部分 F(nes,)，正-散光 F(or)和斜散光 F(ob)。
当角膜散光（C(1)）和 IOL 散光（C(2)）值相等时，IOL 旋转±10 度时，残余柱面为角膜散光的三分之一。然而，在大多数情况下 C(1)大于 C(2)；因此，小旋转不会明显改变残余散光。可以通过以下方式获得消除散光矫正的旋转角 b：cos(π + 2b) = -r/2，其中 r 为 IOL 和角膜柱面的比值。
两种方法给出了等效的结果。当 IOL 柱面值与角膜散光值不同时，选择较低而非较高的柱面值可以降低残余散光。一般来说，IOL 旋转小于 10 度会使眼睛的屈光度变化小于 0.50 屈光度。因此，小的轴旋转不会成为使用散光 IOL 进行满意散光矫正的障碍。
没有作者在提到的任何材料或方法上有经济或所有权利益。
