Defective eyesight, a road safety concern?

Failing eyesight presents safety problems for Europe's older drivers

A new report highlights substantial variation in the assessment of drivers' vision across Europe, and recommends that Member States make moves to better assess drivers' vision. Checking the vision of drivers plays a valuable role in the EU's target of halving road deaths across the EU by 2020. The aim is to achieve this road safety improvement by legislative means that change driver behaviour, raise the technical standards of vehicles and improve road design. As part of the programme, the visual requirements to drive safely in European law are currently being implemented by EU Members States.

While many European countries have good systems in place to assess all drivers' vision, the UK and a small number of other countries continue to rely on an outdated assessment of vision known as the Licence Plate Test that is believed not to be consistent with the underlying standards. Among the proposals put forward by the UK government in its consultation is to retain the Licence Plate Test for car and motorcycle drivers and to lower the current eyesight standard by reducing the distance at which the licence plate is read. In addition, the UK, along with France, Germany and four other countries, has no requirement for ongoing assessment of vision for these drivers, which is seen as a missed opportunity to improve road safety.

One disease is seen as a particular threat and a new campaign by the UK-based International Glaucoma Association (IGA) for 2011 called CAN U C 2 Drive aims to address failing eyesight amongst older drivers. The issue of poor eyesight amongst drivers aged 40 or over represents an increasing safety risk on Europe's roads. Undetected glaucoma is one of the leading causes of preventable blindness in the UK and many countries. This problem primarily, but not solely, affects people aged 40 and over and tackling this easily preventable issue could help address Europe's targets on reducing road accident levels.

According to the IGA, glaucoma affects more than 600,000 people in the UK, yet it is estimated that over half the people concerned are undiagnosed and untreated. The condition affects peripheral vision and without regular testing, people will miss the early onset of the disease, as it has no automatic warning for sufferers. Early diagnosis and compliance with recommended treatments can add on average, up to 12 years of good sight, a period during which most drivers with glaucoma can normally continue to drive safely and with confidence. However the prevalence of glaucoma is increasing in line with the ageing population and its current level of under diagnosis and treatment, creates a safety risk on the road.

The IGA has a strategy in hand for dealing with the problem, explaining how glaucoma affects vision and who is at risk. This encourages all adults over 40 to have a test at an optician so as to help avoid unnecessary sight loss. For those diagnosed with glaucoma, treatment can slow down the progression of the disease and does not necessarily mean the end of the road for drivers.

Glaucoma is a condition in which the optic nerve is damaged where it leaves the eye. This nerve carries information to the brain and as it becomes damaged due to excessive pressure in the eye, vision deteriorates. The pressure squeezes the optic nerve and kills nerve fibres, leading to sight loss. Glaucoma affects the offcentre parts of the field of vision first and does not affect the central vision until its late stages.

Glaucoma is a condition in which the optic nerve is damaged where it leaves the eye. This nerve carries information to the brain and as it becomes damaged due to excessive pressure in the eye, vision deteriorates. The pressure squeezes the optic nerve and kills nerve fibres, leading to sight loss. Glaucoma affects the offcentre parts of the field of vision first and does not affect the central vision until its late stages.

This off-centre damage can go unnoticed, mainly because humans use central vision most of the time. The danger comes when the damaged areas in each eye overlap: instead of an accurate combined visual picture, the brain will reconstruct the missing parts of the picture based on the information it has from the working field of vision. This may give a dangerously inaccurate picture and unexpected events may be missed.

If glaucoma is left untreated, the damage can progress to tunnel vision and loss of central vision, though blindness is rare.

There are four main types of glaucoma and Primary Open Angle Glaucoma (POAG), also known as chronic glaucoma, is by far the most common form. Other types are: Primary Angle Closure Glaucoma (PACG), also known as acute glaucoma; Secondary Glaucoma, where glaucoma is the consequence of another condition; Developmental Glaucoma, despite being very rare, glaucoma can also affect babies, children and teenagers.

There are other risk factors for glaucoma and people of African-Caribbean or Asian origin are at higher risk of developing glaucoma for example, while those with a family history of the disease also facing a higher risk. In addition, both short and long-sighted people are at higher risk and while the link with diabetes is not fully understood, sufferers of that disease also appear to have a higher risk of having glaucoma. It is estimated that 2% of the people aged over 40 have glaucoma, which is equivalent to over 610,000 people in the UK but more worryingly, it is also estimated that over half of all people with glaucoma in the UK remain undiagnosed.

Glaucoma becomes more common with age, especially after 40 and a major problem is that too many people aged 40 and over do not have regular eye tests. Data for the UK shows that 18% of people aged 40-49 have not been for a sight test for five years or more, while a further 6% cannot remember the last time they had a sight test. Worse still, 10% of people aged 50-59 have not been for a sight test for five years or more while a further 2% cannot remember the last time they had a sight test.

Again, this issue is not restricted to the UK but is equally a problem elsewhere in the EC.

The IGA's recommendation is that everyone over the age of 40 should have an eye test at least every two years. Booking an eye health check will allow the tests to be carried out and assessed by an optometrist, who is trained to examine the eyes to detect defects in vision, signs of injury, ocular diseases or abnormality and problems with general health. Eye tests can also be carried out by ophthalmic medical practitioners (OMP); these are doctors who have chosen to specialise in examining eyes and usually practice in Medical Eye Centres.

The examination should include a basic eye test as well as a full eye health check, which includes all three glaucoma tests. They are all painless and together can identify glaucoma long before damage and therefore significant sight loss has occurred. Using ophthalmoscopy, the appearance of the optic nerve can be viewed with a special torch brought close to the eye and this can also be done with a slit-lamp used by many optometrists. Tonometry is a test to measure the pressure within the eye and the common air puff test is used for screening many optometric practices. Alternatively contact tonometry is more accurate and is recognised because a drop of anaesthetic will be put into the eye before the test. Lastly, perimetry is a test to map any areas of reduced or defective vision in the periphery of the visual field. There are many different instruments that may be used to check the field of vision, but in most cases the patient will be asked to fix their eye on a central dot of light and press a button when they see flashes of light or wavy lines in any direction. All three tests together increase the detection rate of glaucoma by four times when compared with ophthalmoscopy alone.

The most common type of glaucoma is Primary Open Angle Glaucoma, or Chronic Glaucoma, and is usually treated with eye drops that reduce the pressure to a level at which no further damage occurs to the optic nerve. But if eye drops do not provide a sufficient pressure lowering effect, laser or surgical treatments are available. Research suggests that a treated glaucoma patient would progress from mild to at least unilateral blindness in approximately 35 years, while those untreated patients would take just 23 years. Treatment reduces the developing or worsening of glaucoma by approximately 60% and those taking the necessary steps are still able to drive for many years.

2737 ICM Research carried out an on-line survey for the IGA in the UK and these showed that whilst 96% of respondents described glaucoma as an eye disease, most were unaware of its impact on vision. Worse still, 52% did not know that glaucoma mainly effects peripheral vision while 30% of people did not know how the disease is diagnosed and 14% inaccurately felt that the condition is identified when people recognise their sight is declining. The IGA's recent research also shows that many drivers do not test their eyes regularly enough and could miss the onset of the condition. Some 30% of respondents aged 40-54 fail to take an eye test every two years. Just 9% of this group of respondents reported they take an eye test about every three years while 17% reported taking an eye test less frequently than every three years and most worryingly, 4% said they had never had an eye test. Again, there is evidence that this problem may be at least a similar risk in many or most European countries, with some showing even higher risks. For those countries where eye health screening is even less frequent, the risk to road users is substantial.