[Visual acuity and traffic accidents].

In the first part of the study it was established that professional truck or bus drivers whose central photopic visual acuity in one or both eyes is less than 0.7 differ distinctly from their colleagues with fully adequate or only slightly reduced photopic vision in that they are involved in accidents more frequently (the difference is statistically significant, and in some respects highly significant). This applies in particular to accidents after 15 years' driving (known as late accidents) and accidents of the following types: priority infringements, ramming from behind, turning, and changing lanes. The first hypothesis on which the study was based, namely that accidents become more frequent as central photopic vision deteriorates, was confirmed. The second part of the investigation, which was likewise carried out with license-holders who drove professionally, produced a similar result: Drivers with considerably reduced twilight vision and/or considerably increased susceptibility to glare are more frequently involved in certain accidents at night than those who fully satisfy the minimum requirements for these visual functions. In particular, it was established that almost every fifth professional driver involved in a night-time collision with another road user (ramming, side-to-side collisions) has severely diminished twilight vision and that one out of four have increased susceptibility to glare. Thus, the second hypothesis, i.e., that the number of night-time accidents increases as twilight vision deteriorates and the driver's susceptibility to glare increases, seems fully confirmed.