The shortwave, high-energy blue portion of visible light can be harmful to the human eye!
Many in-vitro tests have shown that blue light causes oxidative damage of retinal receptor cells and advances the development of age-related macular degeneration (AMD). This (to date incurable) eye disorder slowly destroys the area of sharpest vision (also known as the macula lutea or “yellow spot”), and can lead to significant visual impairment. In Germany, AMD is the leading cause of visual impairment in old age, accounting for more than 50% of vision problems. One in three people aged 65 and above already show first signs of macular degeneration in eye checks.
The macula lutea contains very few receptor cells for short-wave light. It derives part of its name from lutein, a yellow pigment concentrated in this area that filters short wavelengths of light and thus protects this area of sharpest vision.
Artificial light over-saturated with aggressive blue light induces excessive stress to the filter pigment in the eye, leading to the death of receptor cells. Creeping blindness then sets in.
Blue light is more dangerous for the retina than UV radiation since the ultraviolet portion of UV light is already filtered out by the anterior parts of the eye, such as the cornea and the lens. By contrast, visible short-wave light travels unhindered through the eye to the retina, producing oxidative stress.
Short-wave blue light also impairs sharp vision because the macula lutea mainly contains receptor cells for green and especially red light.
Special absorptive filters such as blue blocking and comfort filters can help protect the eye from oxidative damage and improve eye health.
Whereas traditional light protection lenses reduce transmission of visible light evenly across the spectrum, blue blocking filters cut off part of the light spectrum at a defined point and absorb all short-wavelengths of light below this point.
Visible blue light has a higher percentage of short wavelengths than red light, for instance, and thus carries more energy. It is scattered even more within cloudy ocular media such as cornea, lens or vitreous humour. This light scatter increases glare and reduces contrast.
Blue blocking filters absorb the blue portion of the spectrum, thus reducing glare and considerably increasing contrast.
Benefits of blue blocking filters:
Spectacles with blue blocking or comfort filter lenses are recommended for people who spend a lot of time outdoors. Protecting the eyes from harmful UV light and the aggressive blue portion of visible day light is more important than ever.
In terms of their blocking capacity, filters are classified as UV blockers absorbing all light below 400 nm or as blue blockers that absorb visible blue light in addition to UV light.
UV blockers offer high light transmission across the entire spectrum, while cutting off radiation below 400 nm.
Consequently, they fully absorb ultraviolet light. In healthy human eyes, the cornea absorbs UVB rays and the lens absorbs long-wave UVA rays. This means that although UV light cannot damage the retina, it can still harm the anterior part of the eye. (For instance, exposure to UVB rays can cause conjunctivitis.)
When looking through a blue blocker, images are perceived to be brighter, especially with a 450 filter. Higher spectral sensitivity to yellow as the opposite colour of blue also gives the impression of increased brightness.
However, increasing contrast with blue blocking filters comes at the expense of natural colour vision, which becomes increasingly distorted as more blue light is filtered out.
As a result of this colour distortion, blue blocking filters that absorb all light up to 511 nm are only suitable for daytime driving, while 527 filters are not permitted for on-road driving in most jurisdictions. In many countries, however, 400 and 450 nm blue blockers meet traffic signal recognition requirements.
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A high proportion of blue in daylight increases light scattering in the eye’s optical media. The scattered light superimposes the other colours and reduces the contrast of the retinal image. Special filter lenses, such as the IV PROSHIELD comfort filters have been developed to improve colour vision while having a blue attenuating effect.
They selectively filter out the blue portion of sunlight that often superimposes the other light colours to an ideal level (thus complying with traffic signal recognition requirements). In addition, comfort filters feature the typical properties of blue blocking filters. By improving the contrast of objects in diffused or dim lighting, they provide a more natural visual experience. Glare is minimised without giving users the impression they are in the dark once they move into the shade. Comfort filters maintain all spectral colours; only the amount of blue light is reduced. Since blue receptors are extremely sensitive, we only need a small amount of blue to perceive it. Yellow and green light is allowed to pass fully. This is why comfort filters offer natural colour vision while enhancing contrast.
Be it for water sports, mountain biking, skiing, gliding or golfing, comfort filters offer perfect vision and optimal eye protection for all outdoor activities. In combination with additional tints, their contrast enhancing ability makes the difference for the wearer during leisure activities with fast movements taking place in very bright ambient lighting.
Our eyes also perform at peak level in front of computer screens. Glare and irradiation often result in fatigue and eye strain. Comfort filters help minimise selected wavelengths to a tolerable level and increase contrast. Users benefit from improved visual processing and mental receptiveness. Their performance increases significantly.
Additional tints for blue blocking and comfort filters reduce light transmission across the entire light spectrum and minimise glare outdoors, ensuring undisturbed vision.
Combining them with an extra tint (of the kind used for standard sunglasses) also helps ensure that comfort filters are perceived as less stigmatising.
Tinted blue blocking filters are often used for sports activities to increase contrast. They are ideal for winter or water sports, golfing and competitive shooting. Comfort and blue blocking filters provide the ultimate visual experience.
Light also enters the eye from above and from the side. Studies have shown that about 30 to 60% of unfiltered and scattered light enters around standard sunglass frames. This reduces the protective benefits of even the best sunglass lenses, all the more so since the pupils widen behind dark lenses.
A sophisticated frame design that provides protection both from the top and the sides is as important as the filter lens.
Lenses that wrap round the eyes are ideal since they prevent scattered light from entering from the sides. This can also be achieved with wide temples or side windows. A pronounced top rim offers additional protection from light entering from above.
Blue blocking and comfort filters combined with trendy frame designs that have been completely thought through provide optimal light protection and help preserve the retina from damage.