Section of Occupational Medicine
advise his patient when an illness or its treatment, or alcohol abuse, renders him unfit to drive or continue to drive safely, is much greater now that the law relating to private car licences has changed. The Road Safety Act 1974 makes a private car driving licence, subject to certain safeguards, valid from the date of issue to the age of 70. The declaration of health at the initial issue of a licence continues, but that previously made at each triennial renewal of a licence is replaced by a general obligation on the licence holder to notify the licensing authority at any time if he becomes aware of the onset of or worsening of any physical or mental condition which would impair, more than temporarily, his ability to drive safely. The law not only requires the licence holder to declare 'relevant disabilities', the old 'bar disabilities', but also any other disability likely to cause a vehicle driven by him to be a source of danger. The legislation also extends the concept of 'relevant disabilities' by including 'prospective disabilities'. A prospective disability is defined as a 'disability which is not of such a kind that it is a relevant disability but which, by virtue of the intermittent or progressive nature of the disability or other wise may become a relevant disability in the course of time.' The driver need not notify the Licensing Authority if 'he has reasonable grounds for believing that the duration of the disability will not extend beyond a period of three months'. From this, two problems arise: (1) there will be conditions the progress of which is so uncertain that a judgment on the likely effect on driving will have to be left to a later stage, and (2) in some cases a doctor will not wish to disclose to a patient. the nature of his condition. In such cases the doctor will have a special responsibility to take action at the appropriate time. This action is, of course, to remind the patient of his legal obligation. Under the law, therefore, it is the responsibility of the driver not to drive while his ability to drive properly is impaired by illness or treatment. But this responsibility cannot be exercised effectively unless the driver is given the necessary medical guidance. The Medical Commission on Accident Prevention has recently published a third edition of 'Medical Aspects of Fitness to Drive' (1976) which gives general advice about the effect of medical conditions on fitness to drive and, in particular, about relevant and prospective disabilities. Any doctor who is in doubt about the advice he should give his patient in any particular case can discuss the matter with a doctor at the Medical Advisory Branch of the Driver and Vehicle Licensing Centre at Swansea. REFERENCES Grattan E & Jeffcoate G E (1968) British Medical Journal i, 75
243
Havard J D J (1973) Proceedings of the Public Works Congress 1972; p 482 Medical Commission on Accident Prevention (1976) Medical Aspects of Fitness to Drive. 3rd edn. Ed. Andrew Raffle. MCAP, London Norman L G (1958) Lancet ii, 807 Raffle P A B (1974) British Journal of Industrial Medicine 31, 152 Road Safety Act (1974) HMSO, London Ysander L (1970) Acta chirurgica Scandinavica, suppl. 409 (1973) Congress of the International Driver Behaviour Research Association, Zurich (unpublished)
Dr J F Taylor (Department of Transport Driver and Vehicle Licensing Centre, Swansea, SA6 7JL)
Some Aspects of the Health of Long-Distance Drivers There are nearly one million heavy goods vehicle and public service vehicle drivers in Great Britain at the present time, about one-twentieth of the entire working population; and 80 000 of these are self-employed. There is inevitably a wide difference between the health control of the self-employed group and of drivers in the larger transport undertakings such as London Transport, which provides an excellent occupational health service. Generally, the larger the organization, the greater the prospect of providing alternative non-driving employment in the event of unfitness on health grounds. There is a difference between the heavy goods vehicle driver and his airline counterpart, whose pay is substantially greater and who is able to afford to indemnify himself by insurance against financial loss due to premature retirement due to ill health. Some heavy goods and public service vehicle operators are considering insuring their driver employees in a similar fashion.
The Law The law in relation to the licensing of heavy goods and public service vehicle drivers states that an applicant shall not (1) at any time since he attains the age of 3 years, have had an epileptic attack; or (2) suffer from any disease likely to cause the driving by him of a heavy goods vehicle to be a source of danger to the public. Causes of Sudden Collapse at the Wheel Table 1 shows the diagnosis in 52 cases of sudden collapse at the wheel occurring in Great Britain during the last four months. It will be seen that the average age of collapse in cases of epilepsy is 35 years. Interestingly enough, insulin-induced hypoglycemia has equal place with epilepsy, and the average age of the drivers was found to be 44.
244
Proc. roy. Soc. Med. Volume 70 April 1977
Epilepsy and Long-Distance Driving More than half of the convulsive seizures occur during sleep, most of them after dozing off or just before waking. Inactivity of the mind tends to promote attacks, which are more likely in a relaxed state than when the mind is fully active. If one contrasts the earlier heavy goods vehicle with its sophisticated modern counterpart, the most noticeable differences are in the provision of comfort for the driver. Noise levels in the driver's cab have been substantially reduced, heaters are now provided - in some transcontinental cabs air conditioning is the order of the day. The majority of long-distance drivers' cabs are fitted with radios, some with stereo cassette facilities. Schedules are tight, delay means loss of a bonus. Turn-and-turnabout shifts are worked and insomnia is not an uncommon feature in men temporarily staying in lodgings and cut off from family and friends. Thus a man with a tendency to drowsiness associated with shift work insomnia may drive for monotonous hours along motorways, seated in a comfortable (ergonomically designed) heated cab, listening to soft music. These are ideal conditions for an attack of epilepsy in a person with this tendency. Moreover, with increasingly congested roads, the risk of an accident due to an epileptic attack at the wheel is increased. What use can a driver make of any symptoms of an impending attack if he is on a crowded motorway? British law may seem harsh, but some countries have a total bar in respect even of febrile convulsions in infancy, there being evidence that these may lead to brain damage and a subsequent seizure pattern. It should be emphasized that the licensing authorities do have difficulties in determining whether an applicant for a licence has suffered an attack of epilepsy since the age of 3 years. Doctors completing medical examinations for licensing purposes are specifically asked the question, as indeed are applicants. But a history of fits at the
age of, say, 6 years may well be unknown to a driver or to the examing doctor. A study of Licensing Centre records reveals that some 25 % of people with epilepsy have never been told that they suffer from that condition, but that they suffer from faints. In deciding the issue it is therefore necessary for medical assessors carefully to study previous medical records. British motor insurance is geared to legal liability, and this depends in the United Kingdom on establishing negligence. Generally speaking, the law does not regard damage resulting from a sudden or unexpected attack of epilepsy, or indeed any other disability, as being caused by negligence. However, where a doctor, but not his patient, has knowledge of an attack of epilepsy since the age of 3 years but fails to record this on the statutory medical examination form for a heavy goods vehicle licence, that doctor may be held negligent and liable to third-party damages in the event of an accident due to epilepsy. Another aspect of the law is that it does not distinguish between the different varieties of epilepsy. Thus over the age of 3 years consciousness need not be lost for an attack to constitute epilepsy. For example an aura, as the beginning of an attack, is regarded in law as an attack; as are myoclonic seizures, which may well of course be subject to secondary generalization with a fullblown grand mal convulsion. Licensing authorities have to determine, on the balance of probabilities, whether a given attack was epilepsy. Epilepsy is the only absolute 'bar disability' specifically prescribed in law in relation to heavy goods and public service vehicle driving. Once it has been established, on the balance of probabilities, that a given attack occurred after the age of 3 years, it is mandatory for the licensing authority to apply the regulations as approved by Parliament. The regulation allows no discretion whatsoever. Epilepsy apart, the licensing authorities in general apply the standards as set out in the Medical Commission on Accident Prevention's pamphlet 'Medical Aspects of Fitness to Drive'.
Table I
Contact Lenses Heavy goods and public service vehicle driving is in the main a dirty task. Heavy goods vehicle drivers are responsible for the correct loading of their vehicles, they have to adjust tarpaulin sheets and ropes. Some groups of drivers are responsible for emergency maintenance; for example in the event of a puncture they might have to change a wheel. Public service vehicle drivers may have to handle coins or baggage. Certainly the nature of the work is improving, for example containerization has helped. However, these heavy goods vehicle drivers do work to tight schedules and are involved in relatively long hours at the wheel. They do not have immediate access to washing facilities, nor do
Road traffic accidents caused by collapse of driver at wheel: diagnosis in 52 casesNo. of Diagnosis cases Epilepsy 14 Ischmmic heart disease 6 Blackouts 5 Cerebrovascular disorders 9 Hypoglycemia (diabetes mellitus with insulin) 14 2 Vertigo Mental illness 2
Average age (years)
35 73 37 50 44
52 0 Notified to the Licensing Centre by the police, July- October
1976
Section of Occupational Medicine
245
they have access to facilities to heat-sterilize a essential in a heavy goods and public service vehicle driver. Dexon et al. in the United States contact lens. Dust and wind can affect most contact lens reported in 1966 that out of 104 who completed wearers. Perhaps the commonest and most im- questionnaires there were 14 with serious eye mediate disabling complication in wearing a hard disease resulting in loss of vision. Ruben in 1976 lens is a foreign body, e.g. a particle of grit working estimated that one in a hundred British contact its way between the lens and the cornea. The lens wearers suffer complications requiring treatcornea is a very sensitive tissue and there is ment, and that 0.080% may suffer some loss of immediate onset of severe pain. In these circum- vision. It is nationally and internationally accepted that stances it is urgently necessary to take out the contact lens, remove the grit particle, resterilize the drivers with virtually monocular vision should not lens and replace it. Due to the nature of the work drive heavy goods or public service vehicles. It will with heavy goods and public service vehicles this is be seen from the above discussion that the contact not possible on the road with dirty fingers without lens-dependent heavy goods vehicle driver might the risk of further foreign bodies, infection or find himself with virtually monocular vision at any damage to the lens. Stone (1970), in her question- moment. There would be insufficient time for him naire to hard contact lens wearers, discovered that to adapt to the situation and in the event of a on average they require four hours to see properly foreign body entering the remaining good eye he with spectacles after removing the contact lens. would suddenly become virtually blind. One can This average does not necessarily apply to all envisage the consequences if this occurred to a bus contact lens wearers and rarely to soft lens wearers, driver approaching a queue of people or to the Additionally the change over from contact lenses driver of a lorry driving at 50 mph on a crowded to ordinary spectacles results in difficulty in bin- motorway. The bulk of contact lenses are fitted for ocular vision. There is a tendency to overshoot or non-medical reasons. These are drivers who can undershoot and the eye needs to rove several times see equally well wearing ordinary spectacles. There is however a small group in which aphaover an object before fixating. There is delayed feedback and consequently delayed response. The kics predominate, whose effective vision for drivdifficulty is that the brain is not accustomed to this ing is dependent on contact lenses. Whilst one has delay, because of the reflexes based on the contact sympathy with this small group whose livelihood lens vision, and the consequent confusion may depends on the wearing of contact lenses, surely result in failure to react to an object obstructing the road safety considerations should have priority. road. Thus it can be said that having a pair of One would certainly not wish to denigrate the spectacles is not always the answer in the case of a tremendous advance in technology that contact driver who has to remove a lens and cannot put it lenses represent. One looks forward to the time back for reasons of hygiene. when further advances in lens technology and Poor hygiene can result in eye infection and environmental arrangements may enable this matinability to tolerate a lens, which therefore has to ter to be reviewed or altered. At the present time be removed. Inflammation of the eye can also be the Medical Commission on Accident Prevention, caused by chemicals used to sterilize the lens. the British Medical Association and the Faculty of Professional drivers are subject to prolonged visual Ophthalmologists of the Royal College of Surconcentration which tends to inhibit reflex blink- geons all advise against the wearing of contact ing. This diminishes the free flow of tear fluid, lenses by heavy goods and public service vehicle causes anoxia and leads to corneal oedema. In turn drivers. this tends to promote infection. It is well known that contact lens wearers are more subject to Deafness and Long-Distance Driving photophobia, glare and flare than other drivers. It is in the essential interests of road safety that These symptoms can be disabling and are most heavy goods and public service vehicle drivers are likely to occur on a long haul. At the present able to communicate in the event of a disaster or moment there is no British Standard for the emergency. Heavy goods vehicles are carrying manufacture of contact lenses, although I under- increasingly dangerous loads, and in the event of stand one is in preparation. Some of the materials spillage in an isolated area it is essential that a employed age rapidly, tending to become opaque, driver should be able to communicate with the with consequent reduction of vision to the wearer, emergency services on the telephone. Some chemiin a matter of months. This particularly applies to cal loads now being carried are capable of insoft lenses, some of which also tear easily; in teraction and the destruction of communities; consequence the heavy goods vehicle driver could recently there have been a number of instances of suddenly find himself with monocular vision in an petroleum and chemical spillage causing danemergency situation. gerous situations. A driver of any heavy vehicle All I think would agree that good vision is breaking down on a dangerous bend must be
246
Proc. roy. Soc. Med. Volume 70 April 1977
capable of urgently communicating so that the obstruction his vehicle is causing can be cleared as soon as possible. In the case of coach and bus drivers, the Canadian Medical Association has pointed to the problem of deaf drivers having to move their heads to hear what passengers are saying to them, thus taking their eyes off the road ahead. Additionally there is the problem of manoeuvring heavy goods vehicles under the instruction of a bystander. A deaf driver who cannot hear instructions (when to stop backing, &c.) may well cause a serious accident. Equally a bystander may see a child crawling under a heavy vehicle and shout to the driver to stop but, alas, the deaf driver would not be able to respond. The Medical Commission on Accident Prevention in its pamphlet recommends that deaf drivers should not drive heavy goods or public service vehicles. The British Medical Association takes a like view. Hearing aids offer no solution to the danger of deafness when driving heavy vehicles; in the event of a road traffic accident they are unfortunately liable to be damaged and lost.
Prosthetic Heart Valves Late complications follow heart valve replacement, the commonest causes of death being thromboembolic phenomena. Kloster reported in 1976 that infectious endocarditis may appear early or late after operation and that it occurs in about 4 % of patients. Somerville in 1976 stated: 'The main disadvantage of prosthetic valves is the need for anticoagulants although this does not obviate the risk of embolism. The shortcomings of tissue valves are the uncertain prognosis after 6 years and the occurrence of fungal infections.' Intravascular hxmolysis occurs with most prosthetic valves but is more severe with certain models, and with a paraprosthetic leak. Hemolytic anemia occurs in 5 % of patients: oral iron replacement is effective therapy. Prosthetic dysfunction due to thrombosis is recognized clinically by the recurrence of heart failure, syncope, cardiomegaly and altered murmurs. Prompt reoperation is indicated for this potentially fatal problem. Systemic embolism has decreased markedly with the introduction of clothcovered prostheses and is frequently related to inadequate anticoagulant therapy. Anticoagulant therapy is recommended for all patients with prosthetic valves unless there is a major contraindication. Bjork in 1976 reported seven years' experience of 1000 heart valve replacements. Thromboembolism was a problem following mitral valve replacements, but in aortic cases this complication was found to be extremely rare as long as anticoagulation was diligently maintained. Rovelli et al. in 1976 have reported a survey of 2600 patients with prosthetic
heart valve replacements. Of these 1229 were mitral valves, 104 were aortic valves and 567 has two or more valve replacements. Thromboembolism was a complication in 160% of mitral cases and 50% of aortic cases. In the case of combined replacements, mitral and aortic valves led to thromboembolism in 21 % of cases and mitral and tricuspid replacement led to thromboembolism in 40 %. Perivalvular leak occurred in 3 %. The survival rate in aortic cases was 81 %, in mitral replacements 59 %, in mitral and aortic combined replacements 67 %, and in mitral and tricuspid replacements 47 %. It seems evident from these reports that at the present time heavy goods and public service vehicle driving is contraindicated for patients who have had cardiac valve replacement surgery. REFERENCES Bjork V 0 (1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 90 Dexon J M, Young C A, Baldone J A et al. (1966) Journal oJ the American Medical Association 195, 901 Kloster F E (1976) 7th European Congress of Cardiology. Abstracts, Book 1. p 91 Rovelli F, Pellegrini A, Marcazzan E et al. (1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 87 Ruben M (1976) Lancet i, 138 Somerville W (I1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 91 a Stone J (1970) American Journal of Optometry 47, 952-964
Dr J D J Havard (British Medical Association, Tavistock Square, London WCIH 9JP)
International Aspects of Driver Licensing The procedures adopted by countries for the issue or renewal of driving 'licences', or, to use the international term, 'permits' should be regarded by public health authorities as screening procedures to identify high-risk groups. The purpose is to exclude, either absolutely or conditionally, those persons whose driving would give rise to an unacceptable risk of danger to themselves and to other road users. Unfortunately, the amount of research which has been carried out on human factors influencing the risk of accident involvement is grossly inadequate in relation to the extent of mortality and morbidity from road accidents and, as has been seen from the two preceding papers, many of the requirements - certainly in the context of medical fitness - have to be based on arbitrary standards unrelated to any quantified risk. In many countries the licensing procedure is most efficient in identifying factors which may have little, if any, influence on the risk, such as minimal defects in static visual acuity or in fields of vision,
advise his patient when an illness or its treatment, or alcohol abuse, renders him unfit to drive or continue to drive safely, is much greater now that the law relating to private car licences has changed. The Road Safety Act 1974 makes a private car driving licence, subject to certain safeguards, valid from the date of issue to the age of 70. The declaration of health at the initial issue of a licence continues, but that previously made at each triennial renewal of a licence is replaced by a general obligation on the licence holder to notify the licensing authority at any time if he becomes aware of the onset of or worsening of any physical or mental condition which would impair, more than temporarily, his ability to drive safely. The law not only requires the licence holder to declare 'relevant disabilities', the old 'bar disabilities', but also any other disability likely to cause a vehicle driven by him to be a source of danger. The legislation also extends the concept of 'relevant disabilities' by including 'prospective disabilities'. A prospective disability is defined as a 'disability which is not of such a kind that it is a relevant disability but which, by virtue of the intermittent or progressive nature of the disability or other wise may become a relevant disability in the course of time.' The driver need not notify the Licensing Authority if 'he has reasonable grounds for believing that the duration of the disability will not extend beyond a period of three months'. From this, two problems arise: (1) there will be conditions the progress of which is so uncertain that a judgment on the likely effect on driving will have to be left to a later stage, and (2) in some cases a doctor will not wish to disclose to a patient. the nature of his condition. In such cases the doctor will have a special responsibility to take action at the appropriate time. This action is, of course, to remind the patient of his legal obligation. Under the law, therefore, it is the responsibility of the driver not to drive while his ability to drive properly is impaired by illness or treatment. But this responsibility cannot be exercised effectively unless the driver is given the necessary medical guidance. The Medical Commission on Accident Prevention has recently published a third edition of 'Medical Aspects of Fitness to Drive' (1976) which gives general advice about the effect of medical conditions on fitness to drive and, in particular, about relevant and prospective disabilities. Any doctor who is in doubt about the advice he should give his patient in any particular case can discuss the matter with a doctor at the Medical Advisory Branch of the Driver and Vehicle Licensing Centre at Swansea. REFERENCES Grattan E & Jeffcoate G E (1968) British Medical Journal i, 75
243
Havard J D J (1973) Proceedings of the Public Works Congress 1972; p 482 Medical Commission on Accident Prevention (1976) Medical Aspects of Fitness to Drive. 3rd edn. Ed. Andrew Raffle. MCAP, London Norman L G (1958) Lancet ii, 807 Raffle P A B (1974) British Journal of Industrial Medicine 31, 152 Road Safety Act (1974) HMSO, London Ysander L (1970) Acta chirurgica Scandinavica, suppl. 409 (1973) Congress of the International Driver Behaviour Research Association, Zurich (unpublished)
Dr J F Taylor (Department of Transport Driver and Vehicle Licensing Centre, Swansea, SA6 7JL)
Some Aspects of the Health of Long-Distance Drivers There are nearly one million heavy goods vehicle and public service vehicle drivers in Great Britain at the present time, about one-twentieth of the entire working population; and 80 000 of these are self-employed. There is inevitably a wide difference between the health control of the self-employed group and of drivers in the larger transport undertakings such as London Transport, which provides an excellent occupational health service. Generally, the larger the organization, the greater the prospect of providing alternative non-driving employment in the event of unfitness on health grounds. There is a difference between the heavy goods vehicle driver and his airline counterpart, whose pay is substantially greater and who is able to afford to indemnify himself by insurance against financial loss due to premature retirement due to ill health. Some heavy goods and public service vehicle operators are considering insuring their driver employees in a similar fashion.
The Law The law in relation to the licensing of heavy goods and public service vehicle drivers states that an applicant shall not (1) at any time since he attains the age of 3 years, have had an epileptic attack; or (2) suffer from any disease likely to cause the driving by him of a heavy goods vehicle to be a source of danger to the public. Causes of Sudden Collapse at the Wheel Table 1 shows the diagnosis in 52 cases of sudden collapse at the wheel occurring in Great Britain during the last four months. It will be seen that the average age of collapse in cases of epilepsy is 35 years. Interestingly enough, insulin-induced hypoglycemia has equal place with epilepsy, and the average age of the drivers was found to be 44.
244
Proc. roy. Soc. Med. Volume 70 April 1977
Epilepsy and Long-Distance Driving More than half of the convulsive seizures occur during sleep, most of them after dozing off or just before waking. Inactivity of the mind tends to promote attacks, which are more likely in a relaxed state than when the mind is fully active. If one contrasts the earlier heavy goods vehicle with its sophisticated modern counterpart, the most noticeable differences are in the provision of comfort for the driver. Noise levels in the driver's cab have been substantially reduced, heaters are now provided - in some transcontinental cabs air conditioning is the order of the day. The majority of long-distance drivers' cabs are fitted with radios, some with stereo cassette facilities. Schedules are tight, delay means loss of a bonus. Turn-and-turnabout shifts are worked and insomnia is not an uncommon feature in men temporarily staying in lodgings and cut off from family and friends. Thus a man with a tendency to drowsiness associated with shift work insomnia may drive for monotonous hours along motorways, seated in a comfortable (ergonomically designed) heated cab, listening to soft music. These are ideal conditions for an attack of epilepsy in a person with this tendency. Moreover, with increasingly congested roads, the risk of an accident due to an epileptic attack at the wheel is increased. What use can a driver make of any symptoms of an impending attack if he is on a crowded motorway? British law may seem harsh, but some countries have a total bar in respect even of febrile convulsions in infancy, there being evidence that these may lead to brain damage and a subsequent seizure pattern. It should be emphasized that the licensing authorities do have difficulties in determining whether an applicant for a licence has suffered an attack of epilepsy since the age of 3 years. Doctors completing medical examinations for licensing purposes are specifically asked the question, as indeed are applicants. But a history of fits at the
age of, say, 6 years may well be unknown to a driver or to the examing doctor. A study of Licensing Centre records reveals that some 25 % of people with epilepsy have never been told that they suffer from that condition, but that they suffer from faints. In deciding the issue it is therefore necessary for medical assessors carefully to study previous medical records. British motor insurance is geared to legal liability, and this depends in the United Kingdom on establishing negligence. Generally speaking, the law does not regard damage resulting from a sudden or unexpected attack of epilepsy, or indeed any other disability, as being caused by negligence. However, where a doctor, but not his patient, has knowledge of an attack of epilepsy since the age of 3 years but fails to record this on the statutory medical examination form for a heavy goods vehicle licence, that doctor may be held negligent and liable to third-party damages in the event of an accident due to epilepsy. Another aspect of the law is that it does not distinguish between the different varieties of epilepsy. Thus over the age of 3 years consciousness need not be lost for an attack to constitute epilepsy. For example an aura, as the beginning of an attack, is regarded in law as an attack; as are myoclonic seizures, which may well of course be subject to secondary generalization with a fullblown grand mal convulsion. Licensing authorities have to determine, on the balance of probabilities, whether a given attack was epilepsy. Epilepsy is the only absolute 'bar disability' specifically prescribed in law in relation to heavy goods and public service vehicle driving. Once it has been established, on the balance of probabilities, that a given attack occurred after the age of 3 years, it is mandatory for the licensing authority to apply the regulations as approved by Parliament. The regulation allows no discretion whatsoever. Epilepsy apart, the licensing authorities in general apply the standards as set out in the Medical Commission on Accident Prevention's pamphlet 'Medical Aspects of Fitness to Drive'.
Table I
Contact Lenses Heavy goods and public service vehicle driving is in the main a dirty task. Heavy goods vehicle drivers are responsible for the correct loading of their vehicles, they have to adjust tarpaulin sheets and ropes. Some groups of drivers are responsible for emergency maintenance; for example in the event of a puncture they might have to change a wheel. Public service vehicle drivers may have to handle coins or baggage. Certainly the nature of the work is improving, for example containerization has helped. However, these heavy goods vehicle drivers do work to tight schedules and are involved in relatively long hours at the wheel. They do not have immediate access to washing facilities, nor do
Road traffic accidents caused by collapse of driver at wheel: diagnosis in 52 casesNo. of Diagnosis cases Epilepsy 14 Ischmmic heart disease 6 Blackouts 5 Cerebrovascular disorders 9 Hypoglycemia (diabetes mellitus with insulin) 14 2 Vertigo Mental illness 2
Average age (years)
35 73 37 50 44
52 0 Notified to the Licensing Centre by the police, July- October
1976
Section of Occupational Medicine
245
they have access to facilities to heat-sterilize a essential in a heavy goods and public service vehicle driver. Dexon et al. in the United States contact lens. Dust and wind can affect most contact lens reported in 1966 that out of 104 who completed wearers. Perhaps the commonest and most im- questionnaires there were 14 with serious eye mediate disabling complication in wearing a hard disease resulting in loss of vision. Ruben in 1976 lens is a foreign body, e.g. a particle of grit working estimated that one in a hundred British contact its way between the lens and the cornea. The lens wearers suffer complications requiring treatcornea is a very sensitive tissue and there is ment, and that 0.080% may suffer some loss of immediate onset of severe pain. In these circum- vision. It is nationally and internationally accepted that stances it is urgently necessary to take out the contact lens, remove the grit particle, resterilize the drivers with virtually monocular vision should not lens and replace it. Due to the nature of the work drive heavy goods or public service vehicles. It will with heavy goods and public service vehicles this is be seen from the above discussion that the contact not possible on the road with dirty fingers without lens-dependent heavy goods vehicle driver might the risk of further foreign bodies, infection or find himself with virtually monocular vision at any damage to the lens. Stone (1970), in her question- moment. There would be insufficient time for him naire to hard contact lens wearers, discovered that to adapt to the situation and in the event of a on average they require four hours to see properly foreign body entering the remaining good eye he with spectacles after removing the contact lens. would suddenly become virtually blind. One can This average does not necessarily apply to all envisage the consequences if this occurred to a bus contact lens wearers and rarely to soft lens wearers, driver approaching a queue of people or to the Additionally the change over from contact lenses driver of a lorry driving at 50 mph on a crowded to ordinary spectacles results in difficulty in bin- motorway. The bulk of contact lenses are fitted for ocular vision. There is a tendency to overshoot or non-medical reasons. These are drivers who can undershoot and the eye needs to rove several times see equally well wearing ordinary spectacles. There is however a small group in which aphaover an object before fixating. There is delayed feedback and consequently delayed response. The kics predominate, whose effective vision for drivdifficulty is that the brain is not accustomed to this ing is dependent on contact lenses. Whilst one has delay, because of the reflexes based on the contact sympathy with this small group whose livelihood lens vision, and the consequent confusion may depends on the wearing of contact lenses, surely result in failure to react to an object obstructing the road safety considerations should have priority. road. Thus it can be said that having a pair of One would certainly not wish to denigrate the spectacles is not always the answer in the case of a tremendous advance in technology that contact driver who has to remove a lens and cannot put it lenses represent. One looks forward to the time back for reasons of hygiene. when further advances in lens technology and Poor hygiene can result in eye infection and environmental arrangements may enable this matinability to tolerate a lens, which therefore has to ter to be reviewed or altered. At the present time be removed. Inflammation of the eye can also be the Medical Commission on Accident Prevention, caused by chemicals used to sterilize the lens. the British Medical Association and the Faculty of Professional drivers are subject to prolonged visual Ophthalmologists of the Royal College of Surconcentration which tends to inhibit reflex blink- geons all advise against the wearing of contact ing. This diminishes the free flow of tear fluid, lenses by heavy goods and public service vehicle causes anoxia and leads to corneal oedema. In turn drivers. this tends to promote infection. It is well known that contact lens wearers are more subject to Deafness and Long-Distance Driving photophobia, glare and flare than other drivers. It is in the essential interests of road safety that These symptoms can be disabling and are most heavy goods and public service vehicle drivers are likely to occur on a long haul. At the present able to communicate in the event of a disaster or moment there is no British Standard for the emergency. Heavy goods vehicles are carrying manufacture of contact lenses, although I under- increasingly dangerous loads, and in the event of stand one is in preparation. Some of the materials spillage in an isolated area it is essential that a employed age rapidly, tending to become opaque, driver should be able to communicate with the with consequent reduction of vision to the wearer, emergency services on the telephone. Some chemiin a matter of months. This particularly applies to cal loads now being carried are capable of insoft lenses, some of which also tear easily; in teraction and the destruction of communities; consequence the heavy goods vehicle driver could recently there have been a number of instances of suddenly find himself with monocular vision in an petroleum and chemical spillage causing danemergency situation. gerous situations. A driver of any heavy vehicle All I think would agree that good vision is breaking down on a dangerous bend must be
246
Proc. roy. Soc. Med. Volume 70 April 1977
capable of urgently communicating so that the obstruction his vehicle is causing can be cleared as soon as possible. In the case of coach and bus drivers, the Canadian Medical Association has pointed to the problem of deaf drivers having to move their heads to hear what passengers are saying to them, thus taking their eyes off the road ahead. Additionally there is the problem of manoeuvring heavy goods vehicles under the instruction of a bystander. A deaf driver who cannot hear instructions (when to stop backing, &c.) may well cause a serious accident. Equally a bystander may see a child crawling under a heavy vehicle and shout to the driver to stop but, alas, the deaf driver would not be able to respond. The Medical Commission on Accident Prevention in its pamphlet recommends that deaf drivers should not drive heavy goods or public service vehicles. The British Medical Association takes a like view. Hearing aids offer no solution to the danger of deafness when driving heavy vehicles; in the event of a road traffic accident they are unfortunately liable to be damaged and lost.
Prosthetic Heart Valves Late complications follow heart valve replacement, the commonest causes of death being thromboembolic phenomena. Kloster reported in 1976 that infectious endocarditis may appear early or late after operation and that it occurs in about 4 % of patients. Somerville in 1976 stated: 'The main disadvantage of prosthetic valves is the need for anticoagulants although this does not obviate the risk of embolism. The shortcomings of tissue valves are the uncertain prognosis after 6 years and the occurrence of fungal infections.' Intravascular hxmolysis occurs with most prosthetic valves but is more severe with certain models, and with a paraprosthetic leak. Hemolytic anemia occurs in 5 % of patients: oral iron replacement is effective therapy. Prosthetic dysfunction due to thrombosis is recognized clinically by the recurrence of heart failure, syncope, cardiomegaly and altered murmurs. Prompt reoperation is indicated for this potentially fatal problem. Systemic embolism has decreased markedly with the introduction of clothcovered prostheses and is frequently related to inadequate anticoagulant therapy. Anticoagulant therapy is recommended for all patients with prosthetic valves unless there is a major contraindication. Bjork in 1976 reported seven years' experience of 1000 heart valve replacements. Thromboembolism was a problem following mitral valve replacements, but in aortic cases this complication was found to be extremely rare as long as anticoagulation was diligently maintained. Rovelli et al. in 1976 have reported a survey of 2600 patients with prosthetic
heart valve replacements. Of these 1229 were mitral valves, 104 were aortic valves and 567 has two or more valve replacements. Thromboembolism was a complication in 160% of mitral cases and 50% of aortic cases. In the case of combined replacements, mitral and aortic valves led to thromboembolism in 21 % of cases and mitral and tricuspid replacement led to thromboembolism in 40 %. Perivalvular leak occurred in 3 %. The survival rate in aortic cases was 81 %, in mitral replacements 59 %, in mitral and aortic combined replacements 67 %, and in mitral and tricuspid replacements 47 %. It seems evident from these reports that at the present time heavy goods and public service vehicle driving is contraindicated for patients who have had cardiac valve replacement surgery. REFERENCES Bjork V 0 (1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 90 Dexon J M, Young C A, Baldone J A et al. (1966) Journal oJ the American Medical Association 195, 901 Kloster F E (1976) 7th European Congress of Cardiology. Abstracts, Book 1. p 91 Rovelli F, Pellegrini A, Marcazzan E et al. (1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 87 Ruben M (1976) Lancet i, 138 Somerville W (I1976) 7th European Congress of Cardiology. Abstracts, Book 1, p 91 a Stone J (1970) American Journal of Optometry 47, 952-964
Dr J D J Havard (British Medical Association, Tavistock Square, London WCIH 9JP)
International Aspects of Driver Licensing The procedures adopted by countries for the issue or renewal of driving 'licences', or, to use the international term, 'permits' should be regarded by public health authorities as screening procedures to identify high-risk groups. The purpose is to exclude, either absolutely or conditionally, those persons whose driving would give rise to an unacceptable risk of danger to themselves and to other road users. Unfortunately, the amount of research which has been carried out on human factors influencing the risk of accident involvement is grossly inadequate in relation to the extent of mortality and morbidity from road accidents and, as has been seen from the two preceding papers, many of the requirements - certainly in the context of medical fitness - have to be based on arbitrary standards unrelated to any quantified risk. In many countries the licensing procedure is most efficient in identifying factors which may have little, if any, influence on the risk, such as minimal defects in static visual acuity or in fields of vision,
