Sources of error in intraocular lens power calculation
Sources of error in intraocular lens power calculation
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DOI：
10.1016/j.jcrs.2007.10.031
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发表时间：
2008-03-01
影响因子：
2.8
通讯作者：
Norrby, Sverker
中科院分区：
文献类型：
--
作者：
Norrby, Sverker
目的：确定和量化白内障手术屈光结果的误差来源。地点：AMO Groningen BV，荷兰格罗宁根。方法：尽可能从已发表的文献中获取或导出影响屈光结果的参数的平均值和标准差（SDs）。为了评估它们对折射的影响，使用了允许非球面的厚透镜光线追踪。计算了各参数对眼镜折射的数值偏导数。一个参数的偏导数和标准差的乘积等于它的标准差，用眼镜屈光度表示，其平方是方差。一个参数的误差贡献是它的方差相对于所有参数的方差之和。结果：术前估计术后人工晶状体（IOL）位置、术后屈光度测定和术前轴长（AL）测量是造成误差的最大因素（分别为35%、27%和17%），平均尺寸眼的平均绝对误差（MAE）为0.6屈光度(D)。人群瞳孔大小的变化占误差的8%，人工晶状体度数的变化占1%。结论：改善屈光效果需要更好的方法来预测术后人工晶状体的位置。用部分相干干涉测量AL可能是有益的。自折射增加了结果测量的精度。用目前可用的方法减少这3个主要误差源，将MAE降低到0.4 d。使用补偿角膜球差的iol可以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和后表面的半径。
PURPOSE: To identify and quantify sources of error in the refractive outcome of cataract surgery.SETTING: AMO Groningen BV, Groningen, The Netherlands.METHODS: 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.RESULTS: 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%.CONCLUSIONS: 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.