SAN ANTONIO – As many head outdoors, eye care experts are reminding people that dark lenses alone do not guarantee protection from the sun’s harmful ultraviolet (UV) rays.
Experts at the University of the Incarnate Word’s Rosenberg School of Optometry say the most important feature to look for when buying sunglasses is UV protection, not the darkness of the lenses.
“The UV light protection is a clear coat; it’s not actually the tint on the glasses,” said Stephanie Schmiedecke Barbieri, dean and professor at the Rosenberg School of Optometry.
Without proper UV protection, harmful ultraviolet rays can pass through the eye and cause long-term damage.
“Ultraviolet light is a short-wavelength light that can enter the eye, and when it does that, it can cause damage, including cataracts and damage to the retina,” Barbieri said.
Homer Martinez, optical manager at the Rosenberg School of Optometry, demonstrated a simple at-home test using a UV flashlight. By shining the light through a pair of sunglasses onto a dollar bill with a UV-reactive watermark, people can get an indication of whether their lenses are blocking ultraviolet light. If the watermark is still visible through the lens, the sunglasses may not provide sufficient UV protection.
The demonstration showed that even a pair of dark-tinted sunglasses failed the test, highlighting that lens color alone does not determine eye protection.
Experts recommend choosing sunglasses labeled “UV 400,” which indicates the lenses block nearly all UVA and UVB rays.
However, UV protection does not necessarily last forever.
“You start to notice scratches on your lenses, and that is absolutely going to be a red flag for you,” Martinez said. “Scratches can actually start to affect any kind of topical coatings.”
Martinez said sunglasses can begin showing signs of wear after about three years, depending on how frequently they are used and how well they are cared for.
For a more precise measurement, the UIW Rosenberg School of Optometry also offers testing with an ultraviolet photometer, which measures how much UV protection a pair of lenses provides. According to the university, a reading below 10 indicates strong UV protection.
During a demonstration, one stylish pair of $60 sunglasses with dark tinted lenses received a poor reading, while a pair of $1.50 SpongeBob-themed sunglasses had an excellent UV protection reading.
Barbieri said price is not an indicator of how well sunglasses protect your eyes.
“As long as it has that UV-400 or that ultraviolet protection that’s met the stringent criteria that we have for glasses, then it meets the criteria that you need to be safe,” she said.
Eye care professionals encourage consumers to verify that sunglasses provide UV-400 protection and replace heavily scratched or aging lenses to help protect their vision from the intense South Texas sun.
Martinez also says to look for frames that fully cover your eyes. Smaller, trendy styles may leave gaps that allow sunlight to reach both your eyes and the delicate skin around them.