Arroyo Rubén, Crespo Daniel, Alonso José
Indizen Optical Technologies SL, Santa Engracia, Madrid, Spain.
Optom Vis Sci. 2012 Apr;89(4):E489-501. doi: 10.1097/OPX.0b013e31824c16fa.
A progressive power lens (PPL) has a relatively complex power distribution, with regions for far, intermediate, and near vision, and also regions affected by aberrations, mainly astigmatism and defocus. Scoring techniques (Sheedy, Optom Vis Sci 2004;81:350-61) have been proposed to mark and classify PPLs according to their optical performance at each region. The objective of this study is to show that although scoring is useful to compare different lens designs, its outcome is highly dependent on the way power is defined and/or computed.
To demonstrate this, the progressive surfaces of many different current designs have been measured with a profiler. From these measurements and by means of exact ray tracing techniques, we obtain both the power maps that we would measure with a focimeter or a typical lens mapper and the power maps that the user perceives at the actual position of use. The scoring technique from Sheedy has then been applied to both types of maps.
It is shown that the parameters that define the characteristics of a PPL when the power map is measured with a standard mapper are not significantly associated with the actual performance of the lens when it is fitted. In a similar way, it is shown that two lenses that have been optimized according to the same target power distribution may get completely different marks depending on the definition of power that has been used in the optimization process. We also propose a graphical method to easily grasp the overall PPL performance by simultaneously presenting four-dimensional information from the scoring technique.
Although in general Sheedy's test is an important tool to compare different PPL designs, it cannot be used to compare those designs optimized for improving user power from classical front side designs when power has been measured for both types of designs with a standard focimeter.
渐进多焦点镜片（PPL）具有相对复杂的屈光力分布，包括远、中、近视力区域，以及受像差影响的区域，主要是散光和离焦。已经提出了评分技术（Sheedy，《验光与视觉科学》2004年；81:350 - 61），根据PPL在每个区域的光学性能对其进行标记和分类。本研究的目的是表明，尽管评分对于比较不同的镜片设计很有用，但其结果高度依赖于屈光力的定义和/或计算方式。
为了证明这一点，使用轮廓仪测量了许多不同当前设计的渐进表面。通过这些测量，并借助精确的光线追踪技术，我们既获得了用焦度计或典型镜片测绘仪测量的屈光力图，也获得了用户在实际使用位置所感知的屈光力图。然后将Sheedy的评分技术应用于这两种类型的图。
结果表明，当用标准测绘仪测量屈光力图时，定义PPL特征的参数与配镜时镜片的实际性能没有显著关联。同样，结果表明，根据相同目标屈光力分布进行优化的两个镜片，可能会根据优化过程中使用的屈光力定义获得完全不同的分数。我们还提出了一种图形方法，通过同时呈现评分技术的四维信息来轻松掌握PPL的整体性能。
虽然总体而言Sheedy测试是比较不同PPL设计的重要工具，但当用标准焦度计测量这两种设计的屈光力时，它不能用于比较那些为改善用户屈光力而优化的经典前表面设计。
