By Sahana Ghosh
Kolkata– Visual parameters such as colour vision, depth perception and contrast sensitivity of drivers influence crash involvement rates in India, says a recent study which also has laid bare the absence of protocols and testing methods in the country to assess the visual capabilities of drivers during their licensing process.
A team of experts led by the Indian Institute of Science (IISc), Bengaluru, found that a whopping 81 percent of drivers – out of a study sample of 387 – who had at least one visual defect, were involved in some sort of an accident.
“There is a huge need to amend the Indian standards of vision testing for drivers. The governing laws in India with respect to driver licensing procedures need to be appropriately amended to create safe drivers by strict visual screening before issuing driving licence,” Ashish Verma, assistant professor, department of civil engineering, IISc and the lead author of the study, told IANS.
The data, published in “Current Science” in April, was culled from investigating the relationship between visual functions of drivers in India with their predisposition to involvement in road crashes.
“Persons with unacceptable standards of visual functions must either be issued a regulated driving licence or licence must be issued only after the problem is rectified, if medically rectifiable,” emphasised Verma.
The analysis involved 387 motorists from the Karnataka Road Transport Corporation (KSRTC), Bangalore Metropolitan Transport Corporation (BMTC) and private transport companies and included motorists from the institute’s community as well.
Among the sampled drivers, colour vision, vertical field of vision, depth perception, contrast sensitivity, acuity and phoria were found to influence their crash involvement rates.
So how are these parameters linked to driving safety?
Acuity, for example, is characterised by the ability to see small details clearly and helps in reading distant traffic signs. Defects in visual acuity results in doubled crash risk, show reviewed literature cited in the paper.
Similarly, phoria refers to the coordination of both eyes to correctly identify obstruction in placement of an object ahead, and affects driving performance as it aids in identifying the position of a vehicle or an obstruction in front of the driver correctly.
“Another interesting aspect observed from the study was that many of the licensed drivers tested did not qualify the minimal vision standards. More than half (52 percent) failed in at least one of the vision parameters tested,” said Verma.
Driver vision skills were tested using a DVS-GT Deluxe vision screener.
But how do motorists wriggle out of tests to get a licence?
Verma explained that Indian driver licensing system follows a single-phase licensing system which recommends a single phase of driver education and training prior to the written and driving tests.
The gaps include driver education not being mandatory and the absence of evaluation of physical fitness of candidates with respect to visual abilities, hearing, etc. before issuing a driving licence.
“Among all the above mentioned visual parameters, acuity is the only parameter evaluated as part of the vision test conducted to issue a driving licence in India. As per the Motor Vehicles Act, 1988, and Central Motor Vehicles Rules, 1989, a self-declaration medical certificate from a registered medical practitioner is sufficient to qualify in the vision test for a driving licence, making the law relaxed,” he said.
“Also, the laws are similar for all, irrespective of age and individual characteristics.”
In contrast, visual acuity, visual field and colour vision are the mandatory vision requirements in countries like Canada, Germany, the USA and Australia.
The assessment and recommendations of the study have been handed over to the Union Ministry of Road Transport and Highways, informed Verma.
“To begin with, these tests should be made mandatory for commercial and public service vehicle drivers, added Verma.
(The co-authors of the study are Neelima Chakrabarty and S. Velmurugan (Traffic Engineering and Safety Division, Central Road Research Institute), B. Prithvi Bhat (Central Institute of Road Transport, Pune), H.D. Dinesh Kumar (IISc) and B. Nishanthi (Department of Civil Engineering, National Institute of Technology, Tiruchirappalli).