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Open every day for every eye in Acadiana

Open Every Day for Every Eye in Acadiana


The Spectrum of Light

Walking outdoors, turning on a light indoors; powering up your laptop—all of these things result in your eyes being exposed to light rays that can have a wide range of effects on your health.

Most patients are aware that sunlight contains visible light rays and invisible ultraviolet light that can harm your skin. However, what many people don't know is that the visible light emitted by the sun comprises a range of different-colored light that contain different amounts of energy.

Light from the sun contains red, orange, yellow, green and blue light rays and many shades of each of these colors, depending on the energy and wavelength of the individual rays. This spectrum of light rays creates "white light" or sunlight.

Rays on the red end of the visible light spectrum have longer wavelengths and less energy, while rays on the blue end of the spectrum have shorter wavelengths and more energy. Blue light have the shortest wavelengths and have invisible electromagnetic rays just beyond the visible light spectrum called ultraviolet (UV) radiation.

UV rays are capable of producing changes in the skin that may create a suntan. But too much exposure to UV can cause a sunburn—and even worse, can lead to skin cancer. These rays also can cause sunburned eyes—a condition called photokeratitis or snow blindness. But ultraviolet radiation, in moderation, also has beneficial effects, such as helping the body manufacture adequate amounts of vitamin D.

Blue Light: Good Or Bad?

One-third of all visible light is considered high-energy visible (HEV) or "blue" light. There are also many man-made, indoor sources of blue light, including fluorescent and LED lighting, flat-screen tvs, computer screens, tablets and smart phones which emit significant amounts of blue light. The amount of HEV light these devices emit is only a fraction of that emitted by the sun. But the amount of time people spend using these devices and the proximity of these screens to the user's eyes have many optometrists concerned about possible long-term effects of blue light on eye health.

Blue light may also increase the risk of age-related macular degeneration (AMD) because blue light penetrates all the way to the retina (the inner lining of the back of the eye). Studies have shown that too much exposure to blue light can damage the light-sensitive cells in the retina and can lead to permanent vision loss.

Blue light may also contribute to digital eye strain. When you're looking at computer screens and other digital devices that emit significant amounts of blue light, this unfocused visual "noise" reduces contrast and can contribute to digital eye strain.

Research has shown that lenses that block blue light with wavelengths less than 450 nm (blue-violet light) increase contrast significantly. Computer glasses with yellow-tinted lenses can help increase comfort when you are viewing digital devices for extended periods of time.

Not all blue light is bad for you. It is well documented that some blue light exposure is essential for good health. Research has shown that high-energy visible light boosts alertness, helps memory and cognitive function and elevates mood.

Many people do not know that blue light is very important in regulating circadian rhythm—the body's natural wakefulness and sleep cycle. Exposure to blue light during the daytime helps maintain a healthful circadian rhythm. But too much blue light late at night (like reading a book on a tablet at bedtime) can disrupt this cycle, potentially causing sleepless nights and daytime fatigue.

A good way to reduce blue light exposure is to use a blue light filter, which are available for phones and computer screens. They prevent significant amounts of blue light emitted from these devices from reaching your eyes without affecting the visibility of the display.

Computer glasses, like LensCrafters Featherwates Blue IQ, can be helpful to reduce blue light exposure from digital devices. These lenses are infused with two main natural eye protectants—ocular lens pigment and melanin—in the optimal ratio to help block UV and filter harmful blue light while preserving natural color perception.

Ask your Today's Eyecare optometrist about special glasses to protect your eyes from blue light.