The Business of Blue Light

Out of THE BLUE

A primer on what you need to know, and how you can better serve your patients and their blue light exposure

Blue light—those light rays on the short-wave end of the visible light spectrum—helps in color perception, and plays a role in regulating a body’s circadian rhythm and mood. But prolonged exposure to high levels of blue light, also called high-energy visible (HEV) light, can be harmful to eyes.

Thanks to our growing reliance on digital screens (a major source of HEV light), our exposure to blue light is higher than ever before. It’s a topic with which every ECP should be familiar, and talking about with patients.

THE BASICS

Blue light is commonly considered to be that light between 400nm and 500nm on the spectrum. It is the most scattered of the visible light rays, and therefore, causes chromatic aberration (and why blue light-filtering lens products also provide crisper vision). The wavelengths most damaging to the macula are at about 460nm.

Lens products ranging from lens materials to coatings have been developed that filter or block specific ranges of the wavelengths without distorting color perception.

HEALTH RISKS

There is accumulating research that indicates exposure to high levels of blue light increases the risk of developing age-related macular degeneration, as blue light wavelengths have been found to kill photoreceptor cells. Visible light goes directly to the retina, and the shortest wavelengths (blue light) can cause damage. Blue light exposure has also been linked to aggravating epilepsy and migraines, and reducing the retina’s sensitivity to color.

Image courtesy of Essilor. Lenses shown above: Crizal^® Prevencia™

WIDE AWAKE

Blue light can also affect the body’s natural sleep/wake cycle, as it is what suppresses the secretion of melatonin (our “sleep” hormone). Overexposure to blue light can therefore cause the body to want to stay awake when it should be sleeping.

WHY NOW?

Considering that eyes have been exposed to blue light since time began, why hasn’t anybody raised concerns before? The answer lies in technology. The LED screens that are on every digital device we use emit high levels of blue light. The energy-saving new lightbulbs are also a huge source of blue light rays. So we are exposed much more now than ever before.

— Susan Tarrant