With the increasing popularity of electronic devices—most of which emit blue light—more and more people are recognizing the importance of blue light protection. Driven by this market demand, major manufacturers have eagerly launched blue light blocking eyeglasses. But how effective are they, and what exactly is blue light? As a professional eyewear supplier, we are here to shed light on blue light today.
What is Blue Light?
Blue light typically refers to the portion of visible light with a wavelength between 400-500nm. It is widely present in natural light and artificial light sources (especially LEDs). With the widespread use of LED lighting and digital devices like smartphones and computers, we are exposed to significant amounts of blue light radiation every day.
The Dual Nature of High-Energy Blue Light
Animal studies have shown that high-energy blue light (400-500nm, peaking around 440nm) can damage the photoreceptor cells in the retina, leading to macular degeneration and impaired vision. This has become a key basis for many businesses to promote the potential harm of blue light to human eyes. Modern lighting and display backlights use LEDs, which emit abnormally high levels of blue light. Observing the ubiquitous “phubbers” (people glued to their phones), it’s clear that smartphones have drastically changed our lifestyle. Blue light is a crucial factor regulating the body’s melatonin secretion: natural daylight suppresses melatonin production during the day, while its secretion at night induces drowsiness. Therefore, frequent smartphone use at night (when LED backlights emit high proportions of blue light) disrupts melatonin balance, making it increasingly difficult to fall asleep.
The Benefits of Blue Light
Night Vision: Unlike the human eye’s sensitivity to yellow-green light (550nm) during the day, night vision primarily relies on rod cells’ response to blue light (around 500nm, as shown in the figure below). This is why many vehicle headlights now use light sources with high blue light components.
Eye Development in Children: Research indicates that blue light plays a positive role in the eye development of growing children. The persistently high myopia rate among Chinese teenagers may be partly attributed to insufficient exposure to natural blue light during outdoor activities (alongside heavy academic pressure and excessive digital device use). Many experts have advocated for increased outdoor activities for adolescents.
Based on the above analysis, blue light poses potential risks but also offers undeniable benefits. Additionally, maintaining balanced, clear vision for all-day wear must be considered. On the other hand, modern lifestyles involve more prolonged and intense exposure to digital devices than ever before (evidenced by the prevalence of phubbers and IT professionals). Adapting to this change is essential. The widely recognized and reasonable approach (adopted by most reputable eyewear brands) is a conservative selective block of 15-20% of blue light.
Choosing Blue Light Blocking eyewear Products
There are various blue light blocking lenses on the market. How should you choose? Technically, there are two common implementation methods: tinting and coating.
1.Tinting Blue Light Blocking eyewear
Tinting involves adding specific dyes to the lens material to absorb blue light within a certain spectral range. Different levels of blue light protection are achieved by adjusting the tint depth.
2. Coating Blue Light Blocking eyewear
By adjusting the coating thickness, the reflection curve is enhanced in the blue light range to achieve protection. Such lenses typically have a bright blue or purple-blue appearance. Demonstrations with blue light flashlights clearly show blue light being blocked, which is highly persuasive to consumers. However, this type of protection reduces light transmittance—easily noticeable when the lens is placed on white paper. The reason is simple: higher reflection inevitably leads to lower transmittance, which may cause discomfort during all-day wear. Incidentally, this blue light blocking coating only needs to be applied to the front surface; the back surface (closer to the eye) should use a regular anti-reflective coating to reduce glare from rear reflections (see the difference between the two light tubes in the figure).
Important Notes on Blue Light Protection
Blue light has potential risks but also benefits. The necessity of blue light blocking varies by individual and depends on one’s lifestyle.
The core purpose of eyeglasses is to provide clear vision. More blue light blocking is not better—balancing light transmittance and protection is crucial.
High-quality products should minimize color distortion (test by placing the lens on white paper) and feature different coatings on each side (high blue light reflection on the front, regular anti-reflection on the back).
Blue light blocking eyewear products are not recommended for growing children and professionals requiring high color accuracy (e.g., designers).
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