Why Is Aging and Night Driving a Problem?
As we age, our eyes usually begin to fail long before we notice it. For example:
Driving at night, especially when it's raining, can be particularly
- Pupils shrink and don't dilate as much in the dark as we age, reducing the amount of light entering the eye. Various reports indicate that the retina of an 80-year-old receives far less light than the retina of a 20-year-old. This can make older drivers function as though they are wearing dark sunglasses at night.
- The aging cornea and lens in the eye become less clear as we age, causing light to scatter inside the eye, which increases glare. These changes also reduce contrast sensitivity — the ability to discern subtle differences in brightness — making it harder to see objects on the roadway at night.
- An older person may test well in the eye doctor's office but still struggle to focus on the road at night, where lighting is poor and more complex visual tasks are required. According to the National Traffic Highway Safety Administration, advancing years decrease our ability to see stationary and moving objects, including cars or pedestrians that might cross the road in front of us. Our ability to resist glare and see reflective road signs and markings also decreases with age.
- Many people's eyes have optical imperfections called higher-order aberrations that can't be corrected with eyeglasses or contact lenses. These aberrations increase with age and reduce vision, especially when the pupil dilates at night, according to 1999 research published in Investigative Ophthalmology and Visual Science.
- Age-related macular degeneration, glaucoma, diabetic retinopathy or cataracts affect 33 percent of all people age 40 and older — the same percentage who have nearsightedness, farsightedness and other refractive errors, according to The Vision Council. So even if you are lucky enough not to have a refractive error, you still are at significant risk of developing other common diseases affecting older eyes.
These problems, combined or in isolation, "may cause such a gradual decline in vision that a driver doesn't realize he has become visually impaired," says ophthalmologist Elaine G. Hathaway, MD, speaking on behalf of The Vision Council.
Sight-Threatening Eye Diseases
|Cataract|| - Cloudy or blurry vision |
- Faded colors
- Headlights, lamps, or sunlight that appear too bright
- Halos around lights
- Poor night vision
- Double vision or multiple images in one eye
- Frequent changes in your eyeglasses or contact lens prescription
|Diabetic retinopathy|| - Severe vision loss, even with no initial symptoms |
- Blurred vision
- Specks of retinal blood, or spots, affecting your vision; spots may clear without treatment, only to be followed by severely blurred vision, severe vision loss and blindness
|Glaucoma|| - No symptoms initially |
- Gradual decrease of peripheral vision
- Eventual loss of peripheral vision and blindness
|Dry macular degeneration|| - Blurred vision, which is a common early sign |
- Inability to see details clearly at a short distance as disease progresses
- Small, growing blind spot in central vision
|Wet macular degeneration|| - Straight lines appear crooked |
- Loss of central vision
|Source: National Eye Institute, U.S. National Institutes of Health|