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The importance of healthy vision for road safety

Reading road signs at a distance enables you to get off the highway at the correct exit. Seeing the dials on your dashboard keeps you from driving too fast or running out of gas.

Clear vision isn’t only important to your own safety. It can affect family members or friends riding with you, the people in vehicles around you and even pedestrians. Knowing how eyesight affects driving, and taking simple steps to improve your vision, can greatly reduce the risk of an accident.

Road safety and vision: By the numbers

Before you get behind the wheel, consider these statistics:

  • 90%: Up to 90% of the information needed to make safe decisions while driving comes through your eyes.

  • 23%: Nearly 1 in 4 drivers cannot see clearly, despite the fact that 80% of vision impairments can be prevented or treated.

  • 3 seconds: Driving just 30 mph with uncorrected vision can require an extra 3 seconds to recognize and read road signs.

  • 3,700: Around the world, road accidents take an average of 3,700 lives every single day.

  • 2X-4X: Fatal car accidents are 2 to 4 times more likely to happen at night.

  • 2.5X: Drivers with unaddressed cataracts are 2.5 times more likely to be involved in an accident.

SEE RELATED: What to expect from a DMV vision test

How your eyesight plays a role in road safety

When you get behind the wheel, different aspects of your vision are called into action:

Clarity

Clear vision is a necessity on the road. It gives you the best possible ability to read distant signs, the information on your dashboard and any other objects that come into your field of view.

Many U.S. states require a corrected visual acuity measurement of 20/40 or lower to get a driver’s license, but the closer you can get to 20/20 vision, the better.

Blurry vision can be linked to many eye conditions, but it’s most commonly caused by:

Glasses, contact lenses and vision surgery can all be used to treat the symptoms caused by these conditions. In the case of cataracts, surgery often completely restores clear vision.

SEE RELATED: Test your vision at home with a printable eye chart

Binocular vision and depth perception

Good judgment of space and distance is crucial to road safety. If you have to squint a lot or have very different prescriptions for each eye, it can impair your binocular vision — when both eyes work together to give you a three-dimensional view of your surroundings.

Night vision

Poor vision in low-light conditions can affect your ability to drive safely after dark.

Night driving is more dangerous than driving during the day, so you need your vision to be clear and sharp. Headlights and streetlights can also cause uncomfortable glare at night, but anti-reflective lens coatings can often reduce this glare.

READ MORE: What is night blindness?

Visual field

Your visual field is the amount of space you can see without turning your head. A visual field of 120 degrees — one-third of a complete circle — is needed to safely operate a vehicle.

It’s also important that you have no significant defects to the 20-degree field in the center of your vision.

Blind spots and tunnel vision can severely interfere with a person’s ability to drive safely. These symptoms can be caused by conditions such as:

Glare

When you’re driving at night, glare can distract and even temporarily blind you, changing the way you react to signs, road markers and other cars.

Cataracts, corneal scars, glaucoma and simply getting older can all affect the amount of glare you see. You may also notice starburst or halos around headlights and streetlights, adding more distractions to your field of view.

If they’re caused by a specific condition, treatment may help reduce or eliminate these sensations.

Otherwise, eyewear options include:

  • Anti-reflective coating on prescription eyeglasses to reduce reflections caused by the eyeglass lenses themselves.

  • Sunglasses that block 100% of UVA and UVB rays during the day to help reduce glare caused by the sun.

  • Polarized sunglasses, which include a special coating that reduces glare and reflections even more. Polarized lenses should only be worn during daylight hours.

LEARN MORE: How to choose sunglasses for driving

How to maximize road safety with simple vision precautions

Ensure your vision on the road is as clear as possible by taking a few simple steps:

Get regular eye exams

Seeing an eye doctor every year or two helps identify and treat any vision conditions.

Sometime after age 40, for example, you’ll start to notice the effects of presbyopia — age-related farsightedness. An eye doctor can prescribe progressive lenses, which will help you see near, far and all distances in-between.

In addition to monitoring for eye disease, regular exams ensure your vision prescription is always current, providing the sharpest vision possible.

Find the right pair of glasses

After your eye exam, an eye doctor can help you find the best glasses for your vision and lifestyle.

If you drive into the sun during your morning or evening commute, or if you regularly drive at night, anti-reflective lenses could help you see more comfortably. For daytime driving, a pair of prescription sunglasses or photochromic lenses specially designed for driving can boost clarity and comfort.

RELATED READING: Night driving glasses: Help or hoax?

Keep your windshield and glasses spotless

Seeing clearly behind the wheel starts with a clean windshield and spotless glasses, since smudges and defects can make it harder to see while you’re driving.

If your windshield has a lot of “pits” or other permanent damage, consider getting it replaced. The same applies to your glasses: If lenses are scratched or starting to show wear and tear, it’s probably time to get new ones.

READ NEXT: Driving in fog


Adam Debrowski also contributed to this article.

The social and economic impact of poor vision. Vision Impact Institute. May 2012.

Road traffic injuries and deaths—a global problem. Centers for Disease Control and Prevention. Accessed July 2021.

Differential effects of refractive blur on day and nighttime driving performance. Investigative Ophthalmology & Visual Science. April 2014.

Older drivers and cataract: Driving habits and crash risk. The Journals of Gerontology. April 1999.

The most dangerous time to drive. National Safety Council. Accessed July 2021.

Glaucoma and driving ability. Glaucoma Research Foundation. Accessed July 2021.

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