If you’re concerned about your vision while driving at night, you’re not alone. In fact, the College of Optometrists reports that almost four in ten people in the UK feel nervous about driving at night, often finding it difficult to recognize hazards, judge speed or distance, or simply feel confident while driving. Since many people experience these issues but rarely discuss them, we asked an expert to shed some light on why this happens.
Night driving can feel surprisingly different from daytime driving. Many people find that navigating the roads becomes more challenging after dark and they may begin to avoid driving at night altogether. This can be especially confusing when an eye exam doesn’t show anything abnormal, yet you feel something has changed.
Mr Alex Day, consultant ophthalmologist based in London, UK, explains that the difficulties of night driving can be missed in standard eye tests, which use high-contrast black letters on a white background.
“However, real daily life, especially at night, is a low-contrast environment,” he says. “A person may have ’20/20′ vision on a chart, but struggle to recognize a pedestrian dressed in black in front of a fence.
“This discrepancy often causes a loss of confidence – drivers may compensate by driving erratically, slowing down unexpectedly, or hesitating at junctions. This can be dangerous in itself.”
Mr Alex Day, a consultant ophthalmologist based in London, UK
How does headlight glare affect night vision?
While glare can sometimes result in the development of cataracts, light from oncoming headlights and other sources can also make driving at night difficult.
Day outlines several modern factors for this, including LED headlights that emit more blue light than traditional halogen bulbs and the increasing number of taller vehicles such as sport utility vehicles (SUVs).
As we age, our pupils become smaller and less responsive, which means less light reaches the retina. The retina is a thin layer of tissue at the back of your eye that catches light and converts it into electrical signals for your brain to interpret as images.
Day explains that, for example, the retina of a 60-year-old person receives only one-third as much light as that of a 20-year-old. He compares it to “driving with sunglasses on.”
“At the same time, the lens of the eye hardens and begins to lose clarity—an early sign of cataract development—which increases the dispersion of incoming light,” he says.
“This scattering can create starbursts or halos around the headlights. As the pupil size changes at night, the eye’s focus shifts slightly towards nearsightedness (myopic shift), distance vision becomes blurry and road markings become harder to see clearly.”
Is it age or eye problems?
The only reliable way to determine whether changes in night vision are due to natural aging or an underlying eye condition is to consult a health professional.
Day explains that normal age-related changes occur gradually and usually affect both eyes equally. Eye conditions, on the other hand, are often detected during routine eye exams with your local optometrist, which is recommended at least every two years.
He recommends seeking professional attention soon if you notice:
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Sudden changes in your vision.
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A significant difference between your eyes.
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That other people see more clearly than you in certain lighting conditions or environments.
Even if your vision seems perfectly normal during the day, it is wise to make an appointment with your optometrist to make sure your eyes are healthy.
“You should never ignore the loss of visual field – such as failing to see people or cars coming from side streets until the last moment,” says Day. “In the context of night driving, if you are dazzled by oncoming headlights or it takes an unusually long time for your vision to return to normal, it means your eyes are struggling.”
He adds that repeatedly drifting out of your lane or cutting curbs are warning signs that your vision may not be safe for driving.
How often should you test your night vision?
Day recommends that all drivers over the age of 60 have an annual eye exam, or sooner if they notice any changes.
“When you book, mention the difficulties of driving, especially at night,” he advises. “A standard test checks ‘high contrast’ vision, but an optometrist may also test ‘contrast sensitivity,’ which better mimics real-world conditions like driving in rain, fog, or darkness.
“They will also examine your eyes using a slit lamp microscope to help identify early lens clouding (cataracts).”
Certain health conditions and lifestyle habits can affect the quality of your vision, affecting how clearly you can see both during the day and at night.
Day highlighted several common causes of low vision:
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health status – Uncontrolled diabetes, for example, can cause inflammation in the lens of your eye, causing prescription fluctuations that make night vision unpredictable. It may also contribute to the early development of cataracts.
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medicines -Certain medications, including antihistamines, antidepressants, and blood pressure medications, can cause dry eyes. Dry eye surface scatters light, which significantly impairs vision.
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Tiredness – Vision doesn’t just depend on your eyes, it also depends on your brain. When you’re tired or stressed, your brain processes slow down, making it harder to filter out visual ‘noise’ like glare and react to threats.
Day warns: “Drivers who have had less than 4 hours of sleep in a 24-hour period have about 10 times the risk of crashing than those who have had a full night’s rest.
“Being sleep deprived is like driving drunk.”
Tips for Safe Driving at Night
There are several practical steps you can take to improve your visibility and confidence when driving at night.
Day recommends making sure your eyeglass prescription is up to date and asking your optometrist about anti-reflective coating, which can help reduce glare from headlights.
“Avoid yellow-tinted ‘night driving glasses,’” he warns. “Although they may feel more comfortable, they actually reduce the amount of light entering your eyes, which can be dangerous in low-light conditions.
“Finally, keep your windscreen thoroughly clean inside and out to reduce light scattering caused by dirt or grime.”
If you are concerned about whether it is safe to drive at night, discuss your concerns with a health professional.
If you have a ‘near miss’ or feel unsafe, Day urges you to stop driving at night and seek medical advice.
“However, I will make important assurances,” he says. “Age-related decline is not always a one-way street to giving up your keys. The most common cause of night driving issues is early cataracts, and cataract surgery is transformative – usually restoring night vision to a quality you haven’t experienced in decades.
“Similarly, treating dry eye or updating the prescription can often resolve the problem. Don’t assume this is the end of the road, as it is often a mechanical problem that we can fix.”
The day concludes with the realization that many people are hesitant to talk about night-time driving issues, often due to fear of losing their driver’s license.
“In fact, many causes are treatable,” he says. “Although some degree of glare at night is normal, always mention it to your optometrist, who can assess if you are developing cataracts.”
