[Experimental studies on the correction of presbyopia].

As a consequence of the changing population structure the number of older, i.e., presbyopic people in work will increase in the future. At the same time the demands made on vision at work will also increase, as new technologies are introduced. Both of these factors will have to be taken into account by ophthalmologists and the optical industry. As accommodation deteriorates, special glasses become necessary which are suited to requirements for highly qualified work. With this in mind the authors conducted a joint investigation at a precision assembly workplace together with the manufacturing technology laboratory of Duisburg University. The results show that if bifocal or respectively trifocal glasses are prescribed at the right time efficiency can be improved both quantitatively and qualitatively. The specific requirements with regard to spectacles worn at such workplaces result in particular from the fact that, for ergonomic and technical reasons, operating devices and controls are being mounted ever more frequently above the horizontal line of gaze. Therefore, when prescribing the glasses, it is important that not only the correction for close and mid-range vision, but also the size and location of this portion of the lens should be taken into consideration. This is illustrated with a number of examples.