Haigis Wolfgang
Department of Ophthalmology, University of Wuerzburg, Germany.
Saudi J Ophthalmol. 2012 Jan;26(1):7-12. doi: 10.1016/j.sjopt.2011.11.007.
The introduction of new intraocular lenses (IOLs), industry marketing to the public and patient expectations has warranted increased accuracy of IOL power calculations. Toric IOLs, multifocal IOLs, aspheric IOLs, phakic lenses, accommodative lenses, cases of refractive lens exchange and eyes that have undergone previous refractive surgery all require improved clinical measurements and IOL prediction formulas. Hence, measurement techniques and IOL calculation formulas are essential factors that affect the refractive outcome. Measurement with ultrasound has been the historic standard for measurement of ocular parameters for IOL calculation. However the introduction of optical biometry using partial coherence interferometry (PCI) has steadily established itself as the new standard. Additionally, modern optical instruments such as Scheimpflug cameras and optical coherence tomographers are being used to determine corneal power that was normally the purview of manual keratometry and topography. A number of methods are available to determine the IOL power including the empirical, analytical, numerical or combined methods. Ray tracing techniques or paraxial approximation by matrix methods or classical analytical 'IOL formulas' are actively used in for the prediction of IOL power. There is no universal formula for all cases - phakic and pseudophakic cases require different approaches, as do short eyes, long eyes, astigmatic eyes or post-refractive surgery eyes. Invariably, IOLs are characterized by different methods and lens constants, which require individual optimization. This review describes the current methods for biometry and IOL calculation.
新型人工晶状体（IOL）的引入、行业向公众的营销以及患者的期望，使得人工晶状体屈光度计算的准确性需要提高。散光型人工晶状体、多焦点人工晶状体、非球面人工晶状体、有晶状体眼人工晶状体、可调节人工晶状体、屈光性晶状体置换病例以及既往接受过屈光手术的眼睛，都需要改进临床测量方法和人工晶状体预测公式。因此，测量技术和人工晶状体计算公式是影响屈光结果的重要因素。超声测量一直是计算人工晶状体所需眼部参数测量的历史标准。然而，使用部分相干干涉测量法（PCI）的光学生物测量技术已逐渐确立为新标准。此外，现代光学仪器，如Scheimpflug相机和光学相干断层扫描仪，正被用于测定角膜屈光力，而角膜屈光力通常是手动角膜曲率计和角膜地形图的测量范围。有多种方法可用于确定人工晶状体屈光度，包括经验法、分析法、数值法或联合法。光线追踪技术或通过矩阵方法或经典分析“人工晶状体公式”的近轴近似法，被积极用于预测人工晶状体屈光度。对于所有情况没有通用公式——有晶状体眼和无晶状体眼情况需要不同方法，短眼、长眼、散光眼或屈光手术后的眼睛也是如此。人工晶状体总是通过不同方法和晶状体常数来表征，这需要进行个体化优化。本综述描述了当前生物测量和人工晶状体计算的方法。
