Hemphälä Hillevi, Dahlqvist Camilla, Nordander Catarina, Gao Chuansi, Kuklane Kalev, Nylén Per, Hansson Gert-Åke
Department of Design Sciences, Faculty of Engineering, Lund University, Lund, Sweden.
Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden.
Work. 2014 Jan 1;47(3):319-27. doi: 10.3233/WOR-141821.
Sorting mail into racks for postmen is visually demanding work. This can result in backward inclination of their heads, especially more pronounced for those who use progressive addition lenses.
To evaluate the effects of customized working spectacles on the physical workload of postmen.
Twelve male postmen sorted mail on two occasions: once using their private progressive spectacles and once using customized sorting spectacles with inverted progressive lenses. Postures and movements of the head, upper back, neck, and upper arms were measured by inclinometry. The muscular load of the trapezius was measured by surface electromyography.
With the customized sorting spectacles, both the backward inclination of the head and backward flexion of the neck were reduced (3°), as well as the muscular load of the right upper trapezius, compared to sorting with private spectacles. However, with the sorting spectacles, there was a tendency for increased neck forward flexion, and increased sorting time.
The reduction in work load may reduce the risk for developing work-related musculoskeletal disorders due to the positive reduction of the backward inclination of the head. But the tendency for increased neck forward flexion may reduce the positive effects. However, the magnitude of the possible reduction is difficult to predict, especially since quantitative data on exposure-response relationships are unknown. Alternative working spectacles with inverted near progressive lenses ought to be evaluated. They should still result in a positive reduced backward inclination of the head and may not cause any increased forward flexion.
为邮递员将邮件分类到架子上是一项视觉要求较高的工作。这可能导致他们头部向后倾斜，对于那些使用渐进多焦点镜片的人来说尤其明显。
评估定制工作眼镜对邮递员身体工作量的影响。
12名男性邮递员在两种情况下对邮件进行分类：一次使用他们自己的渐进多焦点眼镜，另一次使用带有倒置渐进镜片的定制分类眼镜。通过倾角测量法测量头部、上背部、颈部和上臂的姿势和动作。通过表面肌电图测量斜方肌的肌肉负荷。
与使用个人眼镜分类相比，使用定制分类眼镜时，头部向后倾斜和颈部向后弯曲均减少了（3°），右上斜方肌的肌肉负荷也有所降低。然而，使用分类眼镜时，颈部向前弯曲有增加的趋势，并且分类时间增加。
由于头部向后倾斜得到了积极改善，工作量的减少可能会降低患与工作相关的肌肉骨骼疾病的风险。但颈部向前弯曲增加的趋势可能会削弱这种积极效果。然而，可能减少的幅度难以预测，尤其是因为关于暴露-反应关系的定量数据尚不清楚。应该评估带有倒置近用渐进镜片的替代工作眼镜。它们仍应能使头部向后倾斜得到积极改善，并且可能不会导致任何向前弯曲增加的情况。
