A driver receives most of his information about the road situation through his eyes. Certain minimum vision requirements are laid down before a driver may obtain a licence, but everyone should always remember that their eyesight might slowly get slightly worse as time goes on. Any suspicions of eyesight problems should be followed up without delay because of the serious implications for driving safely.
Section 21 of the 1968 Road Traffic Act requires that before the driving test may be conducted the Minister must be satisfied that the applicant’s eyesight reaches the prescribed manner.
The regulations prescribing the manner of so satisfying the Minister of the standard of sight are set out in SI 385/1989 (Reg. 42).
The need for an eyesight report arises in two ways:
An application for a provisional licence for categories A1, A, B, EB must be accompanied by an eyesight report, unless the applicant previously supplied one which is still valid, or he supplies or had supplied a valid medical report.
As part of a certificate of fitness where necessary by court order or where the applicant is “unfit”. Generally the latter need arises where an applicant for a licence cannot declare that he is free from the prescribed diseases and disabilities in the regulations.
The above regulation prescribes that an applicant’s eyesight report must be from an ophthalmic optician or registered medical practitioner. A thorough examination by the former is usually recommended, whereas a doctor will conduct a more basic test.
This report must be such that it satisfies the Issuing Authority that the applicant’s eyesight complies with (or can be corrected to comply with) the required standards.
Details of these standards are:
Visual acuity not less than 0.4 (6/15) in one eye or 0.5 (6/12) in both eyes together (with contact lenses where necessary).
The applicant shall not suffer from diplopia or defective binocular vision.
The person shall not suffer from a loss of more than 20 degrees in the temporal part of his field of vision.
A person with the sight of one eye only shall have a visual acuity (with corrected lens if necessary) of at least 0.6 (6/10), an unrestricted field of vision in the eye concerned and monocular (intended for the use of one eye only) vision must have existed for sufficient time to allow adaptation.
However, and quite surprisingly in Great Britain there is no mandatory eyesight test before obtaining a licence and a motorist must only be able to read a vehicle number plate from a fixed distance outdoors in bright daylight of 20.5metres (67ft – about five car lengths) However, the police have the power to require a driver, at any time, to undertake an eyesight test in good daylight.
This eyesight check is normally made at the beginning of the normal driving test. If glasses or contact lenses are worn for this eyesight test they must be worn at all times when driving. The motorist is legally obliged to ensure that his vision remains up to the standard of this eyesight test.
The British number plate test is one of the most basic to be found anywhere, and is not very exacting. It requires only about one – third normal vision in one eye, in order to pass it.
Few accidents, about 1 – 5% of the total, are due to vision defects, even in part. Where they are involved, the situation is usually one in which the hazard is difficult to see, because of poor visibility or lighting, for example.
The major aspect of eyesight, which is important for driving, is the sharpness of vision. This is checked with a distance test involving letters on a wall chart.
Long sight or short sight produce blurred images, and the appropriate spectacles rectify both these conditions. Tunnel vision is caused by some eye defects. The normal field of vision is about 160 degrees but it can be narrowed to 90 degrees or less in those affected by tunnel vision.
The most serious condition is the inherited defect of retinitis pigmentosa, which gradually restricts the field of vision until almost nothing remains. Sometimes, those affected compensate by moving their head from side to side. Those afflicted with tunnel vision are not always aware of the fact. If only one eye is affected the other compensates. As peripheral vision is reduced, those with tunnel vision do not see objects such as pedestrians or vehicles outside the narrow field of vision, and this is a potentially dangerous situation. They will also find great difficulty when driving around corners.
A similar effect to tunnel vision can be produced by wearing spectacles with broad sides. These are totally unsuitable for driving and also pose a problem for instructors checking pupils mirror work.
Associated with tunnel vision is the phenomenon of night blindness. The periphery of the eye is used in night vision, and as this becomes affected in those with tunnel vision, night vision gets very poor indeed.
Good Vision for Safety
Colour blindness? can have serious implications for motorists, particularly if it is not recognized. Men are more than likely to suffer from it than women, and the most common defect is red – green blindness. Many people, however, do not realize they are affected. In many cases, colour-blind people can drive satisfactorily, provided they are aware of the defect.
Traffic signals can usually be interpreted by the position of the lights, and the movement of other traffic usually allows accurate interpretations of other lights. Colour blindness is usually inherited, but it may be acquired by excessive pipe smoking, especially if coupled with high alcohol intake.
Good vision is absolutely essential for safe driving. The eyes are the most important of the driver’s senses, as he receives 80/85% of all his information through them. Many people think that their eyesight is better than it actually is. It may have been good once, but it has probably deteriorated over the years. Surveys of large numbers of motorists have found that over 30% failed some aspect of an eyesight test and were advised to have a detailed eye examination.
Those with only one eye should not drive until they have had time to adjust to using the single eye. Plenty of time should be allowed after any eye operation. Once the adaptation has been achieved, it is normally safe to drive, provided there is a full field of vision in the remaining eye.
Elderly people will probably suffer deterioration in vision. This may not be recognized or admitted, and, if spectacles are worn, they may have become useless. All elderly drivers should have their vision checked regularly.
In conclusion good vision is essential for safe driving but also vitally important is its proper use. Looking and seeing are two different things. One can look but not see. Seeing is when the information received is processed and acted on. Terms like scanning, ranging and all round effective observation are appropriate when teaching but the expression of “loose vision” is quite helpful to keep pupils visually alert to recognize and react to hazards early.
Travelling at 60mph is equivalent to approximately 88 feet per second therefore, if a driver perceives danger .25 of a second before another driver then he has an extra cushion of 22 feet to react and deal with it. Thus the “early vision means early decision” advice is certainly worth noting and acting upon.
?The simplest reliable colour test is the Ishihara Colour plates, designed by a Japanese surgeon. The plates are filled with different coloured spots, some of which, in a contrasting colour, form the shape of a number. Colour-blind people have difficulty distinguishing the number from its surroundings, or may be totally unable to recognize the number.