With thanks to the Association of Optometrists 

All vehicle drivers in the UK need to meet specific vision standards to ensure road safety. When applying for a car licence, they are required to read a car number plate from 20 metres, with glasses or contact lenses if necessary.  

The current number plate test is not a reliable test of driving vision because it does not assess all relevant visual functions. As a result, drivers can pass the test without having adequate vision for safe driving. 

HGV, bus and coach drivers, however, face stricter requirements, including a medical and vision check when they first apply for their licence and then every five years after 45, and annually from 65. This does not remove an employer's continual statutory responsibility for ensuring drivers' eyesight is of a safe standard.  

The Drivers and Vehicle Licencing Agency (DVLA) must be informed about certain eye or general medical conditions. Read the DVLA driving eyesight rules. 

Common conditions affecting vision include age-related macular degeneration, cataracts, glaucoma, and diabetic retinopathy. Colour vision deficiencies usually means drivers can see colours but they often find it difficult to distinguish between certain colours, most commonly red and green. Colour vision deficiency affects around 1 in 12 males, but only around 1 in 200 females.  

Poor eyesight can result from various factors, including genetics, eye diseases, medications, and health conditions. Symptoms such as squinting, eye strain, difficulty reading, experiencing glare and double vision can indicate vision problems that need to be addressed. 

Effect on road safety 

Good vision is essential for hazard perception, identification and swift, appropriate reaction. Difficulties seeing signs or objects ahead slows drivers’ visual processing and decision making, which means slower reaction times. 

Driving at night is particularly difficult for many drivers. Glare from headlights can significantly impair visibility, making it difficult to see traffic lights, road signs, pedestrians, and other vehicles. Drivers often squint, look away, or momentarily close their eyes leading to slower reaction times and an increased risk of collision. 

Due to pupil dilation in lower light levels, night vision tends to be poorer than day vision which causes an increase in blurry vision, glare sensitivity and a reduction in contrast. 

Eye conditions such as astigmatism can be especially problematic at night when glare and halos around lights are more pronounced. It causes blurred or distorted vision, often causing drivers with the condition to struggle to see road signs, traffic signals, and other vehicles, clearly. 

Most colour vision deficiencies don’t cause any significant difficulties for road users and are not notifiable to the DVLA.

The benefits of sight tests 

During a sight test, an optometrist checks close-up and distance vision using charts of symbols or letters, with or without glasses. They will also examine the eyes for signs of disease or injury and may use drops to get a better view of the back of the eye. Peripheral vision may also be checked on occasion.  

Following a sight test, optometrists can inform patients if they require any prescription or whether they need to be referred to an ophthalmologist or medical doctor. 

Sunglasses 

Photoreactive lenses, also known as photochromic lenses, can be worn to adjust to changing light conditions by darkening in bright sunlight and becoming clear indoors. However, most photochromic lenses don't get very dark when driving, because modern windscreens block the UV light which activates them, so many drivers prefer prescription sunglasses with a fixed tint when driving in bright conditions.  

Photochromic lenses can also take longer to clear than to darken, which may cause issues for drivers who enter dark spaces, such as woodland or underground car parks, from bright sunshine. 

Varifocals 

Some drivers might require varifocal lenses to provide a smooth transition from distance correction at the top of the lens to near-sight correction at the bottom. They can be beneficial for drivers who need to see both the road ahead and the dashboard clearly. However, some drivers may experience distortion or difficulty adjusting to these lenses, so it's important to seek advice from an optometrist. 

Optometrists can also advise drivers on whether they need to declare certain conditions to the DVLA and how to do this.  

Importance of regular eye tests 

The 20-metre vision test is the legal minimum for driving eyesight. However, this does not mean that this is the limit of an employer or driver's responsibilities with regard to the vision standards. Diligent employers will recognise that eyesight often changes over time, and that regular sight tests are essentially for driver safety and for identifying eye and other health conditions. 

What employers can do 

• Every driver should have a sight test every two years or more often if recommended by an optometrist. By law, most drivers are not required to have a vision test between passing their test (often at 17) and reaching 70. However, given that eyesight can change over time, employers should exceed the legal minimum in order to ensure they fulfil their duty of care.   

• Employers should not rely solely on 20 metre number plate tests, as this does not check all the relevant visual capabilities, and it also has none of the wider health benefits of sight tests. 

• Sight tests are tailored to individual needs and can detect general health issues like diabetes, high cholesterol, and high blood pressure.  

• Employers must ensure that if an optometrist has prescribed corrective lenses, or advised someone not to drive, that these instructions are followed. Research from the Association of Optometrists (AOP) in 2024 indicates that 60% of optometrists have seen patients who continue to drive despite having poor vision. This is a significant increase from 40% five years ago.  

• Employers should also ensure that drivers have updated their driving licences to reflect the need for corrective lenses. This could form part of regular driving licence checks, along with checking the driver owns and uses the appropriate lenses. 

Resources 

More information about the AOP's Don't swerve a sight test campaign can viewed at www.aop.org.uk/Dontswerve  

Drivers can also find out information about looking after their eyes at: www.aop.org.uk/patients