Friendly Optometrist in Redmond, WA
BLUE LIGHT AND OUR EYES
Most people are aware that sunlight contains visible light rays and also invisible ultraviolet rays that can tan or burn the skin. But what many don’t know is that the visible light emitted by the sun comprises a range of different-colored light rays that contain different amounts of energy. Blue light rays with the shortest wavelengths (and highest energy) are sometimes called blue-violet or violet light. This is why the invisible electromagnetic rays just beyond the visible light spectrum are called ultraviolet (UV) radiation.
Sunlight is the main source of blue light, and being outdoors during daylight is where most of us get most of our exposure to it. The blue-turquoise portion of the blue light spectrum helps us produce serotonin, a hormone that makes our mood better. This is why some people in Seattle use special lamps to help with SAD (seasonal affective disorder). But there are also many man-made, indoor sources of blue light, including fluorescent and LED lighting and flat-screen televisions.
Most notably, the display screens of computers, electronic notebooks, smartphones, and other digital devices 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 number of time people spend using these devices and the proximity of these screens to the user’s face have many eye doctors and other health care professionals concerned about possible long-term effects of blue light on eye health.
Although more research is needed to determine how much natural and man-made blue light is “too much blue light” for the retina, many eye care providers are concerned that the added blue light exposure from computer screens, smartphones, and other digital devices might increase a person’s risk of macular degeneration later in life.
Because short-wavelength, high energy blue light scatters more easily than other visible light, it is not as easily focused. 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. Therefore, computer glasses with blue blocking lenses may increase comfort when you’re viewing digital devices for extended periods of time.
In addition, research has shown that blue light can decrease the amount of production of melatonin, a sleep hormone. Studies show that a decreased amount of melatonin, particularly among teenagers, affects the quality of sleep for individuals who spend lots of time in front of digital devices.