Relevance of glare sensitivity and impairment of visual function among European drivers

None listed

Insight in the prevalence of vision impairments in the driving population is important, both for evaluating the effectiveness of the current regulations on visual functions of drivers and for estimating the impact of possible new regulations. In past research, attention has been focussed on demonstrating the direct relation between impairments of visual function and driving (in)capacity. The prevalence of impairments has been infrequently addressed. Large studies on this issue date from several years back and were not performed in Europe. In the present research, we aimed at investigating the prevalence of impairments of a number of visual functions in a variety of European countries. Methods: We investigated 2422 drivers in 5 participating clinics: the Vrije Universiteit medical centre in Amsterdam; the Landesklinik fuer Augenheilkunde und Optometrie in Salzburg; the Universitaets-Augenklinik in Tuebingen; the Centro de Oftalmologia Barraquer in Barcelona and the Universitair Ziekenhuis Antwerpen. Participants belonged to either one of the following age categories: 45-54 years, 55- 64 years, 65-74 years and 75- years of age and older. In addition, we recruited a smaller group with ages between 20 and 30 years, to serve as a reference group. Subjects participated in the measurement of a large number of visual functions: visual acuity, both with driving correction and with best correction, visual field, contrast sensitivity, straylight and Useful Field of View. In addition, subjects were asked to fill in two questionnaires. One questionnaire was about driving habits, driving difficulties and self reported accidents. The other questionnaire was the NEIVFQ25 into vision related quality of life. All subjects underwent an ophthalmological examination, comprising the evaluation of current and past ocular diseases and abnormalities. Results: We found that the prevalence of impairments of visual functions is low in the younger age groups, and raises to relevant percentages in the higher age groups. This counts for all modalities of visual function, but especially for those functions that are not included in the current regulations, such as straylight and Useful Field of View. The percentage of subjects with inadequate correction of their refractive error is rather high and about equal in all age groups. This inadequate correction results in a lower than optimal visual acuity. Conclusions: The present study is the largest study into the prevalence of visual impairments that has been performed in Europe so far. The results demonstrate that there are quite a number of subjects that do not meet the current European standards on visual acuity and visual field, particularly in the highest age groups. The requirements on visual acuity could be met in the majority of cases if refractive errors were adequately corrected. In all age groups, acuity can be improved in a significant number of subjects by optimization of correction of refractive errors, although in the younger groups, the majority of subjects, even with their (sub-optimal) habitual driving correction, still meet the current standards. Our findings regarding the higher prevalence of impairments of contrast sensitivity and straylight in the elderly groups are in concordance with the larger number of eye diseases and abnormalities that are found in these age groups. Past research has demonstrated the importance of adequate contrast sensitivity for driving safety. This suggests, in combination with our results, that contrast sensitivity could have a more important role in the assessment of drivers than in the current regulations. For such role, a better establishment of cut-off values would be necessary. Past research into the role of straylight in traffic safety has been hampered by the lack of an adequate measurement method. Our results demonstrate that straylight sensitivity can be adequately measured in the majority of subjects in a population study, facilitating future research into its relevance.

No related papers found yet.