An evaluation of Tehran intercity bus driver's vision compared with the standards for Iran and Europe

With an ever-increasing number of vehicles on the road, it is inevitable that drivers will need to call upon an increasing use of sensory and motor skills in order to negotiate safely through traffic. Vision is one of the major senses in human beings, and it is definitely necessary for safe driving. Approximately 95% of the sensory input to the brain required for driving comes from vision. For this reason, visual standards were set up in different countries in order to evaluate drivers’ vision. The object of this study was the comparison of visual fitness of bus drivers based on the standards of Iran, England, France, and Finland. Interviews with and eye examinations of 312 bus drivers were done. First, 312 drivers in South, East and Beihaghi Terminals in Tehran, Iran, were randomly chosen. The drivers were interviewed in order to completed a questionnaire regarding the drivers’ individual characteristics and occupational information. Then the drivers’ vision was examined by Snellen’s chart and a conversation test. The findings were analyzed by the SPSS software and statistical tests. Mean and standard deviations of the age and job duration of the bus drivers were 42.78 and 18.15 years, respectively. Mean time duration after last eye examination was 23.19 months (about two years), and the most common cause for eye examination was exchange of driving permission. The best visual acuity was 10/10 in 51.28% of the cases, and the best visual field was 180 degrees on the horizontal meridian in 48.71% of the cases. 11.6% of the cases were not qualified based on Iran’s driving standard, 7.7% based on England’s driving standard, 49.7% based on France’s driving standard and 17.1% based on Finland’s driving standard. The mean age of qualified persons was 42.24 years, and the mean age of unqualified persons was 46.88 years. This difference was significant (P=0.009). Drivers over 50 years of age were found to have significantly lower visual acuity compared with the two other groups (20-50 years of age and under 20 years of age) (P<0.001). There was not a significant difference in visual field among the three age groups. Based on these findings, it is necessary to conduct a major scientific study to establish appropriate standards of vision for issuing permission to drive.