Blinded by the headlights

CELINA-Experts say the lines between headlights illuminating roadways for safe driving and being too bright and potentially hazardous have become blurred.

When driving, especially at night, motorists must be diligent and pay keen attention to the road, other drivers and driving conditions. That can be difficult when one is temporarily blinded by an intense flash of light.

"I think the bigger concern is what it does for your vision at that moment in time," said Dr. Brian Gerlach, an optometrist at Grand Lake Eyecare. "Your light receptors become overwhelmed by the brightness of the light. Your pupils, in the dark, they sort of dilate. When a bright light hits them, they have to contract, and so sometimes, there's just a little delay in that so your light receptors become a little overwhelmed with the bright lights. It takes anywhere from a few seconds to a few minutes for your eyes to readjust after being exposed to real bright light like that."

Gerlach agreed that since car owners and factories have switched to LED headlights, "it seems like they are much more intense."

"A lot of that is related to the light that the LEDs emit, (which) is in the blue or white spectrum (or in) the 6500 to 5000 Kelvin range. That wavelength is more prone to scattering and more prone to inducing glare in the human eye, especially at night," he said.

Lumens measure how much light a bulb emits, according to information from the U.S. Department of Energy. More lumens means the bulb is a brighter light while fewer lumens means a dimmer light. In relation to lightbulbs, a Kelvin measures the color of light. The lower the Kelvin, the warmer and more yellow the light will be. Higher Kelvin means the light will be cooler and more blue.

"(The) big technical change on it (regulations for light brightness) is they used to have headlights when they rate them for warmness for coolness of the light," said Mark Lochtefeld, a service manager at Buds Chrysler Dodge Jeep Ram. "When you buy a household light, a cool light would be 3,500 K. Your LEDs (on) new vehicles are 5,000 K, which is more like the daylight spectrum of light. That makes an appearance difference already. Instead of being yellow, it's more bluish."

Gerlach said white light is made up of all the colors of the rainbow: red, orange, yellow, green, blue, indigo and violet. Certain wavelengths of that type of light are more prone to scattering in the eye.

"The ones that are more in the blue spectrum, when you see these LEDs (that have a) whitish, bluish kind of hue to them, that wavelength of light that those (head)lights are admitting are more prone to scattering in the eye, which is more prone to causing glare," Gerlach said. "When I say scattering, they (blue or white light) don't focus to the back of the eye quite as efficiently as what a wavelength of light that's more in the … yellowish range. Those tend not to scatter as much and tend not to be quite as bright, so they're not as quite as overwhelming to the light receptors."

Lochtefeld said it's likely that when drivers feel like a laser is pointing at them, those headlights were bought aftermarket and installed.

"I've had that comment, 'I'm coming down the road and I'm getting blinded by that guy.' To that direction, a lot of times that's people making modifications outside of what the vehicle should have had or it's just out of adjustment," he said.

Lochtefeld said drivers can purchase a lightbulb that is advertised as 30,000 lumens on Amazon, whereas a factory bulb may have been 7,000 lumens.

"If you make that level of a change, even if your lights are facing in the right height-wise, if they're facing down as you come at, they are so much brighter," he said.

The cost of LED headlights has come down over time, from about $2,500 in 2008 to $800 today.

"As it's become more mainstream, (the prices) have come down and (became) easier for people to afford it," Lochtefeld said.

Gerlach said there are many things drivers can do to prevent being blinded, such as wearing proper prescription glasses or contacts.

"The old-school thought is you try to concentrate (on) the white line on the side of the road," he said. "There's been certain studies on using different types of lenses for night driving and I haven't seen any of the studies that actually report that they actually work. I'm not aware of any special filter that you can wear at night. If your vision is not corrected properly, then you're going to notice more of the glare and more of the effects of the bright lights."

He also said drivers with cars lower to the road can feel blinded more often because the majority of the other vehicles on the road are larger with headlights sitting at eye level.

To help, the National Highway Traffic Safety Administration (NHTSA) in 2022 issued a final rule allowing what's called "adaptive driving beam headlights" on new vehicles.

The headlights, commonly used in Europe, have LED lamps that can focus beams on darkness such as the driver's lane and areas along the roadside. They also lower the intensity of the light beams if there's oncoming traffic. Camera sensors and computers help determine where the light should go.

Lochtefeld lauded NHTSA's decision.

"A lot of cars that have auto-dimming headlights that will turn that shutter down as your car comes toward it, so you don't really notice it as the driver of your car doing this, but that other car coming at it, it kind of looks like the oncoming car is turning its headlight down," he said.

Gerlach added adaptive headlights will concentrate the lights more in areas where it's needed and less of the light will be applied toward oncoming traffic.

"That's the big problem right now, especially in (larger) vehicles…the lights are more elevated. Those lights are now more close to eye level and are more prone to hitting you directly in the eye," he said.

- The Associated Press contributed to this article.