These include "military grade" flashlights and other handheld lights.įurthermore, although an LED bulb and an incandescent lamp might both be rated at the same brightness, the light energy from the LED might come from a source the size of the head of a pin compared to the significantly larger surface of the incandescent source. However, it may be harmful to look directly at many high-power consumer LEDs simply because they are very bright. Industry sources of blue light are purposely filtered or shielded to protect users. High-intensity blue light from any source is potentially hazardous to the eye. However, these sources pale in comparison to the sun, which yields an ambient illumination more than 10 times greater! Brighter still, many retail stores have an ambient illumination twice as great. For example, recent iPhones have a maximum brightness of around 625 candelas per square meter (cd/m 2). It all comes down to this: consumer electronics are not harmful to the retina because of the amount of light emitted. However, it is the bright white-light LEDs, which backlight the displays in smartphones, tablets, and laptop computers, that produce the greatest amount of blue light. Typical screens have individually controlled red, green, and blue LEDs tightly packed together in a full-color device. The screens of modern electronic devices rely on LED technology.
But it may stimulate the circadian clock (your internal biological clock) more than traditional light sources, keeping you awake, disrupting sleep, or having other effects on your circadian rhythm. This blue light is unlikely to pose a physical hazard to the retina. White LEDs may actually emit more blue light than traditional light sources, even though the blue light might not be perceived by the user. (They can also be made to mimic traditional artificial light sources.) This allows light from LEDs to be perceived as almost indistinguishable from white light, or daylight. However, light emitting diodes (LEDs) produce relatively narrow peaks of light that are crafted by the manufacturer. Most incandescent light sources, like sunlight, have a broad spectrum of light. We perceive the world in shades of gray because only one type of photoreceptor, the rod, is maintaining our visual function. When the light is too dim to stimulate the cones, our sense of color is extinguished. On the most basic level, our sense of color is determined by the balance of activity of these three cells. These cells reside within the retina.ĭuring the daytime, the three cone photoreceptors actively sense light, and each has a peak sensitivity in either the blue, green, or red portions of the visible light spectrum. Our perception of color relies primarily on four main light-sensitive cells: three cone photoreceptors and one rod photoreceptor. Blue light, at high enough doses, is therefore more likely to cause damage when absorbed by various cells in our body. However, blue light may be present even when light is perceived as white or another color.īlue light is of concern because it has more energy per photon of light than other colors in the visible spectrum, i.e. As the name suggests, this type of light is perceived as blue in color. What is blue light?īlue light is visible light with a wave length between 400 and 450 nanometers (nm). The amount of blue light from electronic devices, including smartphones, tablets, LCD TVs, and laptop computers, is not harmful to the retina or any other part of the eye. The short answer to this common question is no. (Retinal specialists treat conditions affecting the retina, a thin tissue at the back of the eye that is responsible for vision.) Many people ask whether blue light will increase their risk of age-related macular degeneration and blindness. Every day, retinal specialists are asked about the risks from blue light emitted from electronic devices.
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