“Night-driving” glasses that promise to dim the glare of headlights may not work as advertised, a new study finds.
The glasses, featuring yellow-tinted lenses, have been marketed for years as a way to ward off blinding headlights and make night driving easier. The problem: There’s no scientific evidence they work.
Now a new study, published online Aug. 1 in JAMA Ophthalmology, offers a buyer-beware message. In driving simulation tests, researchers found that yellow lenses did not improve people’s performance over clear lenses—including when they were faced with oncoming headlights.
“When you wear a colored lens, you cut off a chunk of light,” explained lead researcher Alex Hwang of the Schepens Eye Research Institute at Massachusetts Eye and Ear, and Harvard Medical School in Boston.
“It’s basically like wearing sunglasses at night,” he said.
It might be no surprise, then, that the study found no benefits. In fact, the glasses may have worsened drivers’ performance a bit, Hwang said, though the finding was not statistically significant, owing to the small study group.
Robert Massof is a professor of ophthalmology at Johns Hopkins University in Baltimore. The bottom line, he said, is that “the claims about these lenses are not supported by scientific evidence.”
Yellow-tinted lenses have long been used by aviators, skiers and others looking to reduce glare during the day, which makes sense, according to Massof. The argument for using them at night is that they might block some of the blue light from headlights.
“On the face of it, that kind of makes sense,” said Massof, who wrote an editorial published with the study. “But in practice, it doesn’t really work.”
Massof did some of his own calculations, using information on LED emission and “yellow filter absorption spectra.” He estimated that the night-driving glasses tested in this study do reduce glare somewhat but not enough to make any meaningful difference in vision.
For the study, Hwang’s team recruited 22 drivers to navigate simulated nighttime driving scenarios—three times while wearing different brands of night-driving glasses, and once wearing clear lenses. During each simulation, they were confronted with headlight glare at times.
The drivers’ task was to honk the horn as soon as they noticed a “pedestrian” walking along the side of the road.
Overall, the study found, drivers were a bit slower to spot pedestrians when headlights were bearing down on them. Wearing the yellow lenses did nothing to mitigate that.
The four older adults in the study were especially affected by headlight glare: It added 1.5 seconds to their reaction time, compared to 0.3 seconds among young adults. And again, yellow lenses did not help them.
The findings came as no surprise to Dr. Andrew Iwach, a clinical spokesman for the American Academy of Ophthalmology.
He said that while tinted, or “polarized,” lenses can help shield against daytime glare, night vision is different. When you’re trying to drive in low-light conditions, it’s a bad idea to further limit the light reaching the eyes.
Iwach said people who have trouble seeing during nighttime driving should make an appointment with their eye doctor. If they wear glasses or contacts, they might need a new prescription, he said. In other cases, dry eyes might be a factor. The pupil dilates at night, and the dry air of a car might be more bothersome to the eyes at night than during the day.
For older drivers, age-related eye conditions—like cataracts or macular degeneration—may be the culprit.
If eye diseases or outdated prescriptions aren’t the problem, Iwach said, there are some practical measures people can take against glare.
The first? Clean your glasses. That might sound obvious, Iwach noted, but it’s commonly overlooked. He also advised keeping your windshield clean, outside and in.
“A fine film can build up on the inside of the windshield,” Iwach said. “You’d be surprised at how much glare can be generated there.”
Hwang agreed that those steps are wiser than investing in night-driving glasses—which, he noted, can cost around $100.
It is an all too common misconception that yellow tinted or yellow polarized night driving glasses are beneficial for night time driving.
The thought is, the yellow or amber color reduces glare and improves contrast.
However, in reality, when driving at night or dusk in already limited lighting conditions, ANY tint further reduces the amount of light transmitted to the eye, and consequently, further impairs vision.
The problem is compounded as the yellow tint gives the wearer the impression they are seeing better, when in fact the reverse is actually true.
“Yellow ‘Night Driving’ lenses have been shown to provide no benefit in seeing ability at night. They are even hazardous, because they give the driver a feeling of seeing better, which no one has yet been able to explain.
Studies have shown that they actually impair visual performance and retard glare recovery.
Many promoters have made unfounded claims for the ability of amber to improve night vision.
They have employed mass solicitation, usually by mail.
The Federal Trade Commission has correctly ruled that such practices are illegal since the lenses do not perform as claimed.” – Forensic Aspects of Vision and Highway Safety”, Merrill J. Allen, O.D., Ph.D., Et al.
While yellow lenses can be effective for foggy or hazy daylight conditions, they are not effective against headlight glare and should not be worn at dusk or night.
If glare from headlights is a problem, the first step should be a thorough eye examination, as this could be an early indication of cataracts or other medical conditions.
“So-called night driving glasses are generally amber tinted eyewear meant to reduce the glare of oncoming headlights. While they may make the driver feel more comfortable, they also reduce the wearers visibility of the darker portions of the roadway.” – Sunglass Association of America
The best option for night time driving is a pair of spectacles with clear lenses and an AR coating.
The AR coating is beneficial in two ways. First, it minimizes internal reflections within the lenses, reducing halo problems, and second, it increases the transmittance of light through the lens to the eye.
However, it is important to note, if a patient does not normally wear spectacles, AR coated lenses, or any other type of night driving glasses will not improve night vision, as AR coatings only minimize aberrations that are inherent in ophthalmic lenses and night driving glasses will simply serve to introduce those abberations to the wearer’s vision.
Tips for optimal night time driving vision:
– Make sure eyes are examined regularly
– Always wear an up-to-date prescription
– Lenses worn should be clear with an AR coating
– Ensure lenses are clean
– Ensure windshield is clean
– Ensure headlights are clean and properly aligned
Responsible dispensers of ophthalmic lenses should discourage the use of tinted, polarized, or photochromic lenses in night time or dusk driving conditions and not participate in solicitation or marketing of so-called night driving glasses by irresponsible manufacturers.
More information: The American Academy of Ophthalmology has more on vision and driving.
Journal information: JAMA Ophthalmology