Driving Problems

Vision is essential for driving as it his a highly visual task. Good vision helps you identify road hazards, read signs and see your dashboard. Awareness of common vision-related changes and problems can help you and your loved ones stay safe while driving.

Visual Requirements for Driving

Visual acuity and field of vision (visual field) are the most important factors for safe driving. Visual Processing is an important skill as well. Vision regulations for driving vary from state to state, so check local laws to find out what your requirements are.

Visual acuity gauges how clearly you can see and is measured by reading letters on an eye chart. The test tells you whether you need glasses or contacts, or if your prescription needs to change.

Your visual field is how wide of an area your eye can see when you focus on a central point. There are different types of visual field tests. The one most commonly used in the United States is automated perimetry, in which you watch for flashing lights in a special device.

Visual processing abilities, such as spatial relations and processing speed are useful when navigating through traffic and making decisions while driving. The visual demands of driving are intricate. Controlling a vehicle takes place in a visually cluttered environment and involves the simultaneous use of central and peripheral vision.

Additionally, color vision helps you identify traffic signals and brake lights. Contrast sensitivity helps you see pedestrians, lights and road signs in bad weather and at night.

Vision Problems That Affect Driving

Normal, age-related eye changes can affect your vision and your ability to drive safely. These changes include presbyopia, which may impact your ability to see your dashboard or navigation system, and dry-eye, which can reduce the quality of your vision at night. Other conditions that can impact your driving vision include:

Glaucoma

Glaucoma is an insidious disease in which even patients with very advanced disease may maintain 20/20 central vision. However, the peripheral or side vision can be severely impaired. This is of critical importance when considering all of the visual skills needed when driving, particularly when changing lanes or perceiving pedestrians at intersections. Furthermore, the loss of peripheral vision can be very gradual, making it difficult to perceive when one’s side vision is worsening. This is one of the reasons why it has been estimated that 50 percent of people with glaucoma do not know they have it.

Diabetic retinopathy

A disease in which high blood sugar levels cause damage to blood vessels in the retina, stealing both central and peripheral vision. You may experience dark or shadowy patches in your vision, glare, and reduced nighttime vision.

Cataract

A progressive clouding of the natural lens inside the eye that causes blurry vision, glare and halos around lights. Cataracts can also make it harder to see well at night, in bad weather or in low light conditions. And they can gradually diminish color vision. Some classic symptoms that you might experience when driving if you have cataracts are getting too close to other cars, not being able to read signs, bumping into curbs when parking, and double images.

Macular degeneration

A disease in which a part of the retina called the macula becomes damaged and causes loss of central vision. The size, density, and location of the blind spot determine whether you can see well enough to drive safely. Although you may still have sharpness of vision (acuity) that will allow you to legally keep driving, you will want to see a professional before making that decision. For some people, these vision problems quickly become obvious. But for others, they may cause a gradual loss of vision that’s less noticeable. Having regular eye exams can help your ophthalmologist find these changes early, and treat conditions promptly before they cause irreversible vision loss. The American Academy of Ophthalmology recommends regular eye exams by an ophthalmologist starting at age 40.

Driving at Night

At night, lighting is poor and more complex visual tasks are required for safe driving. Be wary of devices that claim to improve night vision. Follow these tips to improve visibility while driving at night:

Make sure your windshield and windows (inside and out), headlights and taillights are clean. Wear clean corrective glasses or contact lenses with an up-to-date prescription. Make sure your mirrors are always properly adjusted. Have your headlights properly maintained and replace broken bulbs promptly so they light the road adequately.

Warning Signs for Driver Safety

Regardless of your age, if you notice any of the following symptoms in yourself or a loved one, make an appointment with an ophthalmologist right away:

A noticeable decrease in vision or blurry vision

Glare or halos when looking at oncoming headlights or streetlights

A dark spot in your central or peripheral vision

Difficulty reading road signs or spotting pedestrians

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