ErgoPractice News – November 2018
The Right LED Headlights for Optimum Vision and Eye Safety
LED headlights have become one of the major lighting sources for modern dentistry and surgery. Most dental professionals today are using LED headlights as their primary light source. When clinicians are purchasing an LED Headlight, the most considered factors may be price, brand, and beam quality which includes beam uniformity, brightness, and color temperature. Although the color temperature is the most important factor for the beam quality, the color temperature is not often a part of the conversation and yet this has a great impact on beam quality, color accuracy, user comfort, and eye safety.
In this article, we will discuss this missing factor to provide a more complete guideline on how to purchase the right LED Headlight for optimum Vision and Eye Safety.
LED Headlights Types
The spectrum of white LED lights consist of two spectral bands: a blue spectral band and a green-magenta spectral band. The center wavelength of the blue spectral band is 445nm which is the center wavelength of LED curing lights and the center wavelength of the green-magenta band is about 555nm. As the blue spectral band becomes stronger over the green-magenta band, the color temperature increases. Figure 1 shows color temperatures of different brand LED Headlights which were measured by the independent Clinicians Report.1
Based on data published by Clinicians Report1 LED headlights available today may be classified into four types according to their color temperature: (1) Neutral (4,000 Kelvin or Less), (2) Cool Type I (5,500 to 6,000 Kelvin), (3) Cool Type II (6,500- 7,500 Kelvin), and (4) Cool Type III (9,000-10,000 Kelvin). Figure 2 shows “Basic LED Reference Examples and Kelvin Color Scale Chart.”
As the color temperature increases, the strength of the blue band over the green-magenta band increases. Figure 3 shows the strength of the blue band over the green-magenta band as a function of the color temperature. As shown in Figure 3, the neutral LED beam has a balanced spectral distribution; the peak of the blue band is similar to the peak of the green-magenta band. The peak of the blue band of the Cool Type I / II / III LED beam is about 50% / 100% / 200% stronger than that of the green-magenta band.
Beam-Forming Optics and Color Accuracy
The color temperature of LED light beams strongly depends on the design of the beam-forming optics. The majority of LED lights use simpler, non-achromatic optics producing a beam that has variable colors and variable beam quality at different working distances. SurgiTel’s patented LED headlight designs use advanced achromatic optics. This combines all wavelengths uniformly throughout the beam spot which eliminates “hot spots” and evens out colors. Achromatic LED beam quality and color are of a high, consistent quality even as the working distance changes.
The SurgiTel Neutral Type LED is formed with achromatic optics and provides the most balanced spectral distribution,1 resulting in the highest color accuracy of objects and the greatest eye safety. This LED Type is also most comfortable for the user to look at for extended periods of time.
Blue Light Hazard
Extreme blue light causes damage to the retina. This includes retinal burning and risk of early-onset macular degeneration.2 Our instincts (which close down the iris of eyes to block too bright light) help protect us from these risks. Sometimes our smallest pupil diameter is still not enough and we will instinctually react by squinting, trying to reduce incoming light even more. One example is looking at the Sun. Our eyes and brain know this isn’t a good idea so our iris shuts down and we squint. Our eye health is helped by these instincts!
Our eyes can absorb shorter wavelengths such as ultraviolet, but eyes are very insensitive to blue wavelengths. Figure 4 shows “Photopic Response Curve of Eyes” and the spectral distribution of an example LED beam. When we look at LED Headlights which have a strong blue band, our eyes cannot block the blue light because the retina is very insensitive to the blue band. Users of Cool Type II and Cool Type III LED Headlights will allow a strong blue light to reach the retina for extended periods.
The risk of blue light hazard from artificial LED light sources is becoming more widely understood and technologies are continually being devised to protect us. Many phones and computers now change to a more Neutral Type coloring at night, when these screens are more likely to be the primary source of light and our pupils do not react appropriately because of our eyes’ insensitivity to LED blue light. Clinicians who use curing lights in their work already understand the blue light hazard as they use protective glasses for these procedures. LED Headlight blue light is less concentrated, but over time the result may be the same.
What to Do With Your LED Headlight Type
Optimum eye safety is achieved with a Neutral Type LED Headlight, and a Type I Cool will be the second-best. If your headlights are either Cool Type II or Cool Type III, you may want to seriously consider switching to either Neutral Type or Cool Type I.
When purchasing an LED Headlight look at the different models and ask yourself “Which one would I prefer to look at for extended periods?” The “bright” instinctual feeling from some lights may seem impressive but take into consideration of how this type of light may impact your eye health. You may be better off purchasing a light that feels “comfortable to look at” than feels “very bright.”
For more information or to view SurgiTel’s achromatic Neutral Type and Cool Type I LED Headlights in person, contact your local representative at Find a Rep.
- An independent, non-profit dental education and product testing foundation, Clinicians Report®, May 2017. For the full report, go to www.surgitel.com/clinicians-report.
- Stamatacos C, Harrison J, The Possible Ocular Hazards of Led Applications. Journal of the Tennessee Dental