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Night Vision, tips for drovers

Use these nine tips to maximize your sight at night

J. Younger

During the upcoming long winter nights, you'll probably do a lot of your commuting in the dark. Do you ever wish you could take a magic pill so you could see better? Unfortunately, you can't do anything to genuinely improve your ability to see at night, say medical experts. Your rods and cones—the photoreceptors in your retinas that work together to detect light at various wavelengths and intensities—are what they are.

And generally speaking, your ability to see at night deteriorates with age. For instance, a 50-year-old needs about twice as much light to see as well after dark as a 30-year-old. Even younger folks who don't otherwise need glasses often suffer from a condition called night myopia—a tendency toward nearsightedness in low-light conditions.

But you can learn to get the most out of what you have. The following tips will help you see better, and drive better, when the sun goes down.

1. Wear a hat and sunglasses during the day

Exposure to bright sunlight, especially at the beach or on the ski slopes, effectively "bleaches" the photoreceptors in your eyes and lengthens the time it takes them to adjust to the dark. Normally, your eyes reach full dark adaptation in about 30 minutes.

But studies show that as little as two to three hours of bright sunlight can delay adaptation by hours. And the longer you stay in the sun, the worse your night vision gets. For instance, 10 consecutive days of full-sun exposure can reduce your visual acuity, range, and contrast discrimination at night by 50 percent. Experts recommend wearing neutral-gray sunglasses and a hat with a brim during the day to maximize your vision at night.

2. Take vitamins

"The photochemical reactions in the retina require a baseline level of certain vitamins, especially vitamin A," says Dr. Jeffrey L. Weaver, clinical care director of the American Optometric Association. A multivitamin does the trick for most people, but your eye doctor or pharmacist can give you the scoop on specific vitamins required for healthy vision.

3. Clean your windshield

Experts recommend cleaning your car's windows inside and out, especially the windshield, at least once a week. Light is refracted through a dirty windshield, which intensifies glare. And you see less reflection in clean glass. Wash your headlights, too. Even a thin layer of road grime can reduce the light they cast by as much as 90 percent.

4. Dim the dash lights

Keep the rheostat (dimmer) on your instrument panel adjusted so that the instruments remain safely legible, but no brighter. The lower the light inside your car, the better you can see outside. Some carmakers, most notably BMW and Pontiac, use red-lit instrument panels. That's because red light's longer wavelength doesn't affect your retinal rods (the receptors most responsible for vision in dim light). Basically, red-lit instruments allow your eyes to maintain their full dark adaptation, so you can better see what's happening beyond your windows.

5. Look away, look away

When oncoming headlights shine into your eyes, resist the temptation to look directly at them. Instead, cast your gaze toward the white line marking the edge of the pavement. The glare won't be as blinding.

6. At night, pump gas with one eye closed

This technique helps with recovery from "flash blindness"—the condition that occurs when a few seconds of brightness robs your eyes of night vision for a while—for example, when you expose your eyes to the bright lights of service plazas. Even a short exposure to bright lights undoes the adaptation process and "resets" the mechanism. You start all over again, slowly working your way back to full dark adaptation. But since your eyes adapt independently, shielding one eye from brightness preserves night vision in the protected eye.

7. Adjust your mirrors

Besides flipping your car's center-mounted rearview mirror to its "night" setting, you can eliminate reflected glare from headlights behind you by adjusting your outboard mirrors properly.

It's easy. While sitting in the driver's seat, lean to the left until your head rests against the window. Adjust the driver-side outboard mirror so that you can just see the rear fender at the inside edge of the mirror. Then sit upright again and tilt your head to the right until it's approximately in the center of the vehicle. Adjust the passenger-side outboard mirror so that you can just see the rear fender at the inside edge of the mirror. These settings not only eliminate blind spots, they also keep the brightest portions of trailing cars' headlights from shining directly into your eyes.

8. Wear eyeglasses with antireflective coating

If you wear prescription glasses, you'll definitely notice a big difference with an antireflective coating. "A typical lens, even a clear one, will reflect 8-10 percent of white light that comes into contact with it," Weaver says. On the other hand, lenses with an antireflective coating transmit more than 99 percent of light and eliminate internal reflections.

And forget about those yellow-tinted "blue-blocker" lenses that supposedly improve contrast in low light. They do block lower-wavelength light—but at night, lower-wavelength (blue) light is the only light available. Since you need all the light you can get after dark, yellow lenses actually make your night vision worse.

9. Get your eyes checked regularly

According to medical experts, people under 40 should have an eye exam every three years; people in their 40s and 50s, every two years; and folks 60 and older, every year. Incipient cataracts are a prime cause of deteriorating night vision and glare sensitivity.

J. Younger, has covered the automotive industry for more than 25 years.

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