Even cheap sunglasses can block UV, but doctors say that isn't the only light to be concerned about

DENVER - In the process of testing several pairs of sunglasses for protection from ultraviolet light, 7NEWS reporter Amanda Kost learned of a lesser known wavelength from the sun that can also damage your eyes.

Sunglasses are important, said board certified ophthalmologist Dr. Michael Miller from The Eye Center of Colorado, because too much sun exposure can damage the eyes. The danger is also enhanced at high altitude.  

"We feel it's really important, especially in a place like Colorado," Miller said.

Many pairs of glasses advertise protection from ultraviolet light, but Miller said that isn't the only kind to be concerned about.

"The sun for sure is probably the biggest source of blue light and it has been linked to macular degeneration very strongly. It can be a devastating condition for someone's sight," Miller said.

Macular degeneration can cause blurred vision and even blindness. Miller also said the condition is becoming more prevalent as the population ages.

"In fact many surgeons put implant lenses in patients that are having cataract surgery that have blue light filters in them," Miller said. "That's how strongly the medical community is starting to feel about the impact of blue light on the eye."

Miller said protection from blue light is related to the color of the lenses in your sunglasses.

"We feel that the brown, yellow, or amber colors are the best in blocking out blue light," Miller said.

More commonly known, and feared, than blue light is ultraviolet light. UV is the same wavelength that can sunburn skin and the CDC says it can also sunburn eyes.

"Sunburned eyes become red, dry, and painful, and feel gritty. Chronic exposure of eyes to sunlight may cause pterygium (tissue growth that leads to blindness), cataracts, and perhaps macular degeneration, a leading cause of blindness," the CDC's website says.

Kost took 25 pairs of glasses to be tested by optician Bob Luna at Eye Center Optical in an ultraviolet light meter. The glasses were purchased at a range of sources, from high-end designers to a dollar store.

Each pair went through Luna's machine and was proven to provide complete protection from the UV light.