Your eyes, in combination with your brain, can see and understand light waves by interpreting them as color. Reds are longer wavelengths while blue and violet are shorter. Light is energy emanated in electromagnetic waves which are measured in nanometers (nm) or billionths of a meter. The longest electromagnetic wavelength that a human can see is 750nm, a brilliant red, and the shortest is deep violet at 380nm. For all the colors in between, you can use the color spectrum mnemonic Roy G. Biv standing for red, orange, yellow, green, blue, indigo, & violet. (Did you ever wonder why tennis balls are that funny color? 555nm is the color the eye is most sensitive to.)
If the light is too long to be seen, it is called “infrared.” Infrared is heat as we know it. A stove puts out a lot of IR. The implications are obvious.
If it’s too short to be seen the light is called “ultraviolet.” Too much UV light causes such things as sunburn and snow blindness.
Recently there has been significant research on “high energy visible” (HEV) light which is at the blue end of the spectrum. The wavelengths of visible light of most concern are the 40nm band of blue-violet light between 415nm and 455nm which computer monitors (or TVs) emit more than any other of the visible spectrum. Recently the HEV band has been implicated in macular degeneration, and exposure to this band also disturbs human sleep patterns and memory. Since we spend many hours looking at TVs and computer monitors, as well as smart phones and tablets – you can imagine the concerns of many in the eyecare industry.
To combat these problems some innovative spectacle lens companies have invented lenses that filter this band. There are two ways of doing this. The first is to make anti-reflective coatings aimed at this band. These lens coatings simply reflect that band of light so it does not pass through. It is difficult to eliminate all the HEV light by this method, but several companies are able to reflect a significant portion.
There are large corporate conglomerates that mass produce such lenses, but the good news is that there is a company right here in our region that makes an HEV antireflective coating. Central Optical, Clarkston, Washington is one of a few completely independent, highly innovative, efficient and proficient manufactures of spectacle lenses in the Northwest if not the entire United States. They do all of our glasses, and they give us incomparable personal service. They make an HEV coating called the RCP (Razar Complete Protection) which also filters UV. Ask for it.
The second way to filter HEV light is to infuse pigment into the surface of the lens material. BluTech lenses are such a product. BluTech filters HEV light and UV entirely. Human pigment or melanin is mixed with the oxidized chemical 4-Hydroxykynurenine mimicking the yellowing nature of the normal human crystalline lens, i.e. the natural lens of your eye which sits in your pupil just behind the color part of your eye or the iris. The melanin/3-OHKyn combination improves visual comfort and enhances vision by filtering many of the easily scattered short wavelengths that cause haze. That’s a lengthy way to say, “BluTech improves contrast.” Further they make it in a sunlens, filtering HEV light from natural sunlight producing extremely sharp and comfortable outdoor vision.
Remember we stated earlier that HEV affects your sleep. If you’ve finalized that last draft at 11:45PM using your new pair of BluTech computer glasses – you may find yourself falling into slumber a little more easily.