Norrby Sverker
AMO Groningen BV, Groningen, The Netherlands.
J Cataract Refract Surg. 2008 Mar;34(3):368-76. doi: 10.1016/j.jcrs.2007.10.031.
To identify and quantify sources of error in the refractive outcome of cataract surgery.
AMO Groningen BV, Groningen, The Netherlands.
Means and standard deviations (SDs) of parameters that influence refractive outcomes were taken or derived from the published literature to the extent available. To evaluate their influence on refraction, thick-lens ray tracing that allowed for asphericity was used. The numerical partial derivative of each parameter with respect to spectacle refraction was calculated. The product of the partial derivative and the SD for a parameter equates to its SD, expressed as spectacle diopters, which squared is the variance. The error contribution of a parameter is its variance relative to the sum of the variances of all parameters.
Preoperative estimation of postoperative intraocular lens (IOL) position, postoperative refraction determination, and preoperative axial length (AL) measurement were the largest contributors of error (35%, 27%, and 17%, respectively), with a mean absolute error (MAE) of 0.6 diopter (D) for an eye of average dimensions. Pupil size variation in the population accounted for 8% of the error, and variability in IOL power, 1%.
Improvement in refractive outcome requires better methods for predicting the postoperative IOL position. Measuring AL by partial coherence interferometry may be of benefit. Autorefraction increases precision in outcome measurement. Reducing these 3 major error sources with means available today reduces the MAE to 0.4 D. Using IOLs that compensate for the spherical aberration of the cornea would eliminate the influence of pupil size. Further improvement would require measuring the asphericity of the anterior surface and radius of the posterior surface of the cornea.
识别并量化白内障手术屈光结果中的误差来源。
荷兰格罗宁根的AMO Groningen BV公司。
在现有文献范围内获取或推导影响屈光结果的参数的均值和标准差（SD）。为评估它们对屈光的影响，使用了考虑非球面性的厚透镜光线追踪法。计算每个参数相对于眼镜屈光的数值偏导数。参数的偏导数与SD的乘积等于其以眼镜屈光度表示的SD，其平方即为方差。参数的误差贡献是其方差相对于所有参数方差之和的比例。
术后人工晶状体（IOL）位置的术前估计、术后屈光测定以及术前眼轴长度（AL）测量是误差的最大来源（分别为35%、27%和17%），对于平均尺寸的眼睛，平均绝对误差（MAE）为0.6屈光度（D）。人群中的瞳孔大小变化占误差的8%，IOL度数的变异性占1%。
屈光结果的改善需要更好的方法来预测术后IOL位置。采用部分相干干涉测量法测量AL可能有益。自动验光可提高结果测量的精度。利用现有方法减少这3个主要误差来源可将MAE降至0.4 D。使用能补偿角膜球面像差的IOL可消除瞳孔大小的影响。进一步的改善需要测量角膜前表面的非球面性和后表面的曲率半径。
