Do you need special glasses for screen use? Or are they a waste of money?

After University of Tennessee, Knoxville student Alyssa Bond started wearing blue light-blocking glasses about four months ago, the headaches she suffered following hours of staring at a screen disappeared.

Bond, who has 20/20 vision, spent close to $300 on the glasses.

For the freshman interior architecture student, who is in front of a screen for at least five or six hours daily, getting the specialized glasses put an end to her eyes watering and improved her sleep, which at times was disrupted by her computer-induced headaches.

“My eyes have stopped watering, which is good, and then whenever I do get done on my laptop after six hours of work I don’t notice any headaches anymore,” Bond said.

The glasses are a technology in and of themselves, often marketed as a tool to shield eyes from blue light that streams out of computer screens, cell phones and other devices.

But some medical experts, both local and national, aren’t buying into the powers the lenses supposedly hold — like preventing damage to eyes caused by blue light.

For one, it’s not actually known whether blue light from devices is harmful to the eyes, according to Dr. Travis Thompson, an optometrist with Hardin Valley Eyecare & Optical PLLC in Knoxville.

So, what is blue light?

Blue light is everywhere, including outside under the sun, Thompson said, noting that it can lead to eye damage like cataracts and growths on the eyes.

But the medical community doesn’t have enough data to conclude whether blue light from devices also can hurt eyes, he said.

Blue light emitted by devices has a different wavelength than the blue light that is channeled from the sun, according to Thompson, who explained that wavelengths that put eyes at risk are between 400 and 430 nanometers.

Most digital devices produce blue light wavelengths above 430 nanometers.

It’s a close call and enough of one to concern physicians, though “we just don’t have enough clinical data to show that it definitely causes damage,” Thompson said.

Selling without science?

Dr. Raj Maturi, spokesperson for the American Academy of Ophthalmology, doesn’t recommend the glasses and neither does the academy.

Maturi, also a practicing retina specialist with Indiana University School of Medicine in Indianapolis, isn’t aware of any data that supports the claim that blue light-blocking glasses can help the eyes.

Blue light by itself isn’t detrimental to the eyes, he said, though excess blue light exposure at night can act as a barrier to falling asleep.

Avoiding sleeping difficulties is really the only benefit Maturi can see blue light-blocking glasses having for avid nighttime screen users. Yet, implementing a special screensaver on devices that reduces blue light seems to be the best remedy, he said.

While Thompson has noticed a slight uptick in the number of consumers investing in these glasses, Maturi can’t say he’s seen a strong recent trend surface with these glasses.

“I’ve been doing this for 20 years and sometimes it becomes a big deal and other times it’s not,” Maturi said.

There’s always someone who has not researched the science behind blue light but who will be promoting these glasses, which draws broader attention to the issue of blue light, Maturi said.

The science continues to evolve but has not changed dramatically, he said.

How can you protect your eyes?

Knoxville ophthalmologist Dr. Gary Gitschlag — who’s practiced for more than 40 years — also discourages his patients from buying any kind of blue light-blocking glasses because he doesn’t see a problem that needs correcting in the first place.

Without any kind of data or evidence to suggest exposure to digital screens sparks any problems or structural damage to the eye, Gitschlag, of Knoxville Pediatric Ophthalmology, doesn’t have a reason to recommend using filtered glasses for children or anyone else “at this juncture.”

However, he acknowledged it’s reasonable to be concerned about long-term effects on the eyes from screens.

Gitschlag, who primarily consults children, encounters parents who ask about how to handle screen time and responds that he can’t verify any eye damage that can be attributed to screens.

To ward against eye strain, Gitschlag advises people take a break from looking at screens.

What's the 20-20-20 rule?

Along with Thompson and Maturi, he points to the 20-20-20 rule: after about 20 minutes of facing a screen, look at something at least 20 feet away for about 20 seconds.

“This allows the eye muscles to relax and then the eye strain doesn’t happen as quickly,” Maturi said, noting that when people stare at information on screens, they typically don’t blink as often, which can tire the eyes as well as make them dry.

Maturi also suggests that healthy individuals be examined by an ophthalmologist by age 40, followed by once every five years.

For children in particular, Thompson urges families to decrease children’s screen time as a huge increase in myopia, or nearsightedness, sweeps the country “due to kids constantly being in front of their device.”

Most optometrists, he said, push for children to spend more time outside during the week.

He doesn’t view blue light blocking glasses as a necessity but believes that they can be helpful to children as a proactive step of protection.

Thompson errs on the side of caution, he said, “because you only get one set of eyes.”

Barbara Shaffer, of Kodak, doesn’t allow her 8-month-old daughter any screen time, worried that doing so could impact her attention span, motor skills, balance and other elements of her development.

But both Shaffer, 28, and her husband, Isaac, are propped in front of screens for a significant chunk of time most days as they both work from home.

The couple purchased blue light blocking lenses about a year ago, though Shaffer hasn’t picked up on any immediate effects.

“I don’t notice a difference either way, but I believe that it’s more of a long-term precaution,” said Shaffer, who also has blue light filters on her computer monitors and on her cell phone.

The mother doesn’t anticipate having to get specialized glasses for her daughter one day, confident that technology will catch up and that she’ll be protected by blue light filters.

“And I think as technology advances that will become pretty standard,” Shaffer said. “That option should become even more readily available than it is now.”