 All of us depend on our
sense organs to receive all information about our surroundings. Vision is one sense that
is absolutely essential for being safe, whether at home or at work or driving on our
ever-choked dangerous roads. Other senses do play an equally important role in our safety
but an excellent visual ability helps the person tide over the situation with remarkable
ease. A driver on the road receives nearly 80 percent of his information through his eyes.
The visual conditions on the roads vary and there may be poor visibility due to various
factors, both natural and man made. Thus there must be a minimum standard below which it
would be inadvisable for anyone to drive in the interest of safety of all. Road accidents
often result from a combination of factors. A particular level of vision that may be
fairly ok in one type of road conditions may spell doom in different conditions.
With the increase in traffic on roads and
change in driving conditions, good vision becomes an essential necessity. But despite the
increasing demands made on the driver of today, the visual standards in most of the
countries have remained what they were at the beginning of the century. As we drive in to
the new millennium, it is essential that we adopt better and improved standards of vision
for safe driving. Let's have a look on what are the various vision problems that one could
have and endanger the driver as well as other road users.
 Hypermetropia and Myopia (long sight and short sight as they are
commonly known) produce blurred images. These generally do not cause many problems in
driving as long as one uses appropriate spectacles. Convex lenses are used for
Hypermetropia and concave lenses for Myopia.
The normal eye has a visual field of around
1600 but those affected by Tunnel Vision have a highly reduced peripheral vision that
could be 900 or even less. With the high density of all kinds of vehicles on the road, a
good peripheral vision is essential. Those affected by it try to compensate by moving
their head from side to side. This helps only to a limited extent. The problem with this
affliction is that those affected by it are not always aware of it. At times only one eye
is affected and the strain is on the other eye. The drivers with this problem do not see
objects such as pedestrians and vehicles outside the narrow field of vision and give rise
to a potentially dangerous situation. Driving around corners also becomes difficult in
case of tunnel vision.
Night Blindness is usually associated with
tunnel vision and as the periphery of the eye is used in night vision the problem becomes
very acute. Colour Blindness is generally inherited but it may be acquired due to various
factors. Colour blindness can be hazardous as it can cause confusion between red, green
and amber signal lights. According to a study a person with red colour blindness requires
four times the normal
intensity of light to see a red light. People with red colour blindness find it difficult
to drive in rain, fog and mist or at night as they are unable to appreciate a red
tail/brake light ahead of them. Wearing of tinted glasses while driving compounds the
problem.
Glare is another very common problem
associated with vision while driving. It crops up during night driving. It is mainly due
to dirt and scratches on the windscreen, causing scattering of light. Smoke from
cigarettes also causes an increase in glare from oncoming headlights at night. It has been
suggested that the windscreens should be replaced every 50,000 miles. Tinted windscreens
and tinted spectacles should be avoided. Many people think that their eyesight is better
than it actually is. Visual functions change with age. What would have been good once, may
have deteriorated now. Hence it is advisable to have regular vision testing. Elderly
people generally suffer from failing visual ability and often restrict to day driving.
To summarise, it would be prudent to state
that it cannot be explicitly stated that poor vision is an  important
cause of road accidents but it should be remembered that there are believed to be over
1000 independent factors affecting driver's behaviour. These could relate to road
conditions, driver and the vehicle. An accident can be caused by a combination of one or
more of these causes. The simplest way to reduce road accidents, may be due to any cause,
is to change the driver's attitude through education.
And now a word of caution about spectacles
that you wear during driving:
· The frame should have thin rims and sides
so as not to restrict peripheral vision.
· Lenses should be impact resistant.
· Tinted spectacles should not be worn, especially during night.
· Photochromatic lenses should also be avoided during night driving.
· Polarising lenses can be effective in reducing the glare from the road. |
