The objective is to investigate difference of metric ruler, videorefactor and pupillometer in measuring pupillary distance (PD).

目的是研究度量尺，视频重构和瞳孔计在测量瞳孔距离（PD）方面的差异。

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Objective To investigate difference of metric ruler, videorefactor and pupillometer in measuring pupillary distance (PD).

目的比较米制直尺、电脑验光机与瞳距仪测量双眼瞳距的差异。

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