Blue Light Lenses with More Protection and Less Reflection (2024)

Product Spotlight CE - Sponsored by ZEISS

Brent McCardle, ABOM

Release Date: September 15, 2021

Expiration Date: May 1, 2023

Learning Objectives:

Upon completion of this course you should understand:

1. Describe the new aesthetic challenge posed by blue filter lens reflections in online meetings
2. Describe the ZEISS BlueGuard blue hazard calculation and why it differs from the BLH function
3. Explain what the ZEISS BVD formula measures and why
4. Explain how short-wavelength blue light exposure affects retinal cells
5. Explain how long wavelength blue light affects our circadian rhythm

Course Description

This course will review blue light fundamentals, wavelength-dependent effects on retinal cells, circadian rhythm, and how the new ZEISS BlueGuard Lens technology increase protection and reduce reflections.

Faculty/Editorial Board:

Brent McCardle, ABOC, NCLE
“Brent McCardle is a dedicated educator with 35 years of optical experience. His understanding of the optical industry encompasses all facets including training and development, teaching ophthalmic optics and advanced ophthalmic theory, managing a surfacing, finishing laboratory and dispensary. He learned to become a better teacher and trainer while he was an Instructor at Durham Technical Community College and he continues to train and educate ZEISS ECP’s and ZEISS representatives in his role Technical Education Specialist. Breg.

Credit Statement:

This course is approved for one (1) hour of CE credit the American Board of Opticianry (ABO). One hour, Ophthalmic Level 2, Course STWJHI046-2.

Support

This is a product spotlight CE supported by an educational grant fromZEISS

This course will review blue light fundamentals, wavelength-dependent effects on retinal cells, circadian rhythm and how the new ZEISS Blue Guard Lens technology increase protection andreduce reflections.

As we spend more time in virtual meetings exposed to digital blue light emitted by our screens, the aesthetics of blue-blocking lenses become more relevant. We see ourselves on the screen just as others see us, and we are becoming increasingly conscious of the prominent blue-purple reflections from our lenses with blue light coatings. ZEISS BlueGuard Lenses solve this problem with their in-material blocking function, producing up to 50 percent less visible blue light reflections from digital blue light compared to blue light coatings. The result is blue light protection, total UV blocking, comfortablevision, excellent lens clarity and superb aesthetics.

More than ever before, we’re spending time infront of digital screens. With the enormous increasein online meetings, we all see how reflective ourlenses can be, particularly lenses with blue filters.Unfortunately, our digital screens expose us to moreblue light emissions creating new challenges for oureyes, while lens reflections create new challenges forlens wear aesthetics. ZEISS BlueGuard Lenses areengineered to balance protection, clarity and aesthetics to mitigate the potential challenges fromdigital light source exposure and lens surface reflections. Using the latest organic-chemical technology,ZEISS BlueGuard Lenses provides an “in-material” solution that blocks up to 40 percent of potentiallyharmful blue light while providing complete UVprotection up to 400 nm.

While longer wavelength blue light can help us stay alert and promote a normal sleep-wake cycle, shorter wavelengths are irritating, reduce visual acu ity and produce potential harmful effects on the eyes. By design, ZEISS BlueGuard Lenses block a sub stantial portion of the potentially harmful blue light while maximizing the good blue light transmission.

THE NEW ONLINE LIFESTYLE

Increased digitalization and modern artificial light sources increase our eyes’ exposure to artificial or digital blue light. The last few years have acceler ated this trend, changing how we work, learn and socialize. Since the pandemic began, worldwide smartphone usage has increased by 70 percent, while laptop usage has increased by 40 percent.¹

A peer-reviewed article in the Indian Journal of Ophthalmology showed that 94 percent of partici pants had increased their screen time during lockdowns. On average, screen time increased from 4.8 to 8.6 hours per day.² Device usage has become an integral part of our daily livesand is likely here to stay, even after the pandemic subsides.

BLUE LIGHT FUNDAMENTALS

Both the eyecare industry and the scientificcommunity are recognizing increased exposurefrom artificially-generated blue light. Blue lightcan have both negative and positive impacts onour eyes—the dualism of blue light. For example, it is scientifically accepted that blue light isessential for our vision, alertness, mood, wellbeing and sleep-wake cycle.

The visible light range for the human eye isbetween 380 and 780 nm. The blue light band(Fig. 1), between 380 and 500 nm, is an essential part of the spectrum relevant to propervision performance and crucial physiologicalprocesses.

Our vision evolved under sunlight, the mostintense natural blue light source (solar bluelight). However, LEDs and digital devices havedramatically increased our daily exposure toartificial and digital blue light.

POTENTIALLY HARMFUL BLUE LIGHT

Blue light can be potentially harmful to oureyes. High-energy visible (HEV) light cancause retinal damage. Shorter wavelengthswithin the blue light spectrum have higherenergy and more significant potential to damage eye tissue.

The blue light band between 380 and 500nm consist of two sub-bands:

1. HEV or blueviolet light, 380 to 450 nm, and
2. Blue-turquoise light, 450 to 500 nm.

Photo-induced eye health risks and the complications of long-term retinal damage like agerelated macular degeneration (AMD) are linked to High Energy Visible light (HEV) exposure. HEV in the spectral range of blueviolet light is an identified causal factor in the development of AMD.³ These high-energy photons interact with biological tissue on a molecular level. There is a general relation between the absorption of higher photon energy and increased potential for detrimentaleffects on eye health.

HEV has the potential to cause oxidativedamage to light-absorbing ocular structures ofthe retina. Unlike UV radiation, blue lighttransmits to the retina and is absorbed by themacular pigment epithelium and photoreceptors. One study found blue light can be moredamaging to the retina than other spectral colors.⁴ Scientists have established the blue lighthazard (BLH) function, highlighting blue lightrisks at each wavelength in the range between390 and 500 nm. BLH is derived from in vitroand animal studies, and describes the weightingfunction for calculated risk of damage at a givenwavelength along the blue light spectrum. Thedata is also included in various industrynorms, standards and publications.

It is appropriate to weigh the potential risks toretinal tissue associated with bright lightsources, such as the sun or arc welders. However,according to the CIE International Commission on Illumination⁵, BLH does not governcommon artificial light sources, such as LEDsor digital devices. As a result, BLH is notparticularly relevant to blue light lenses. In addition, the latest ISO blue light report (ISO/TR20772:2018) notes that blue light up to 455nm delivers the most significant phototoxic riskto the retinal pigment epithelium. Therefore,the report suggests minimizing blue light up to455 nm and maximizing longer wavelengths toavoid interfering with the circadian rhythm andother functions. As a result, ZEISS BlueGuardLenses were designed to partially block bluelight between 400 and 455 nm but allow transmission of longer wavelengths.

At present, there is no scientifically establishedaction spectrum to specifically weigh the ocularrisk from digital or artificial blue light. As aresult, ZEISS does not use any action spectrumcalculations to quantify blue light blocking.

THE BLUE VIOLET BLOCK METRIC

Blue-violet block (BVB) measures the true percentage of potentially harmful blue-violet light,between 400 and 455 nm, being blocked tominimize HEV blue light exposure and stillallow beneficial blue light transmission. Somealternative formulas incorporate a solar spectralweighting factor. But spectral weighting is notan appropriate approach for blue filter lensesbecause they are designed and used predominantly for viewing digital device screens thathave a very different spectral emission profilefrom the sun.

ZEISS introduced this simple metric becausethere is no industry standard to quantify bluelight blocking in spectacle lenses.

BENEFICIAL BLUE LIGHT

Blue light has a good side, triggering physiological processes that control our body’s internalclock, the circadian rhythm. The circadianrhythm sets our 24 our sleep/wake cycle and iskey to our health and wellbeing. Rods andcones are photoreceptors that enable visionunder photopic (daylight) and scotopic (nighttime) conditions. Another class of photoreceptors, the intrinsically photosensitive retinalganglion cells (ipRGCs), do not contribute to vision but detect light intensity, drive pupil aperture control, and other physiological and psychological mechanisms. These specialized retinal ganglion cells play a crucial role in circa dian rhythm, contributing to our wellbeing and sleep-wake cycle. Retinal blue light exposure modulates the hormone melatonin in the ipRGC cells associated with the sleep-wake cycle. The peak sensitivity for melatonin sup pression in the blue light band is around 464 to 490 nm.^{6 ,7} As a result, blue-light-blocking lens es should transmit these beneficial blue light wavelengths and only block the potentiallyharmful short wavelength HEV blue light.

DIGITAL EYE STRAIN

With excessive screen use, many people experiencedigital eye strain. DES symptoms include glare/dazzle, discomfort, blurred vision, accommodationstress and dysfunction, fixation disparity, pain inor around the eyes, dryness and eye fatigue.^{8, 9}

The Vision Council’s Digital Eye StrainReport and other sources show that more thantwo-thirds of adults in the U.S. who regularlyuse digital devices experience symptoms associated with digital eye strain.¹⁰

Formerly known as Computer Vision Syndrome (CVS), the contemporary term of digitaleye strain includes the plethora of eye and visionrelated symptoms and asthenopia challenges associated with the extensive use of computersand digital displays, intense reading and otherextensive near vision tasks. Digital eye strain canoccur when the visual demand exceeds thecapacity of the accommodation and vergencesystem to maintain clear and comfortable vision,resulting in an overload of our visual system,leading to eye strain and visual discomfort.

BLUE LIGHT AND DIGITAL EYE STRAIN

Blue light contributes to digital eye strain, causingsymptoms such as blurry vision and visual discomfort.¹¹ Shorter wavelength blue light can induceopto-physical effects while entering the eye on itspath through the ocular media to the retina. Thetwo main effects are wavelength-dependent lightscatter and longitudinal chromatic aberration.^{12, 13}

The first is linked to the increased scattering(Fig. 4) propensity of short blue wavelengths oflight by the ocular media. In effect, intraocularscatter causes “visual noise,” resulting in perceiveddazzle, reduced contrast and digital eye strain.

Longitudinal chromatic aberration is alsocaused by short-wavelength blue light.Because ocular media’s refractive index varieswith the wavelength, induced optical dispersion effects can cause longitudinal and lateral chromatic aberrations (Fig. 5). The shorterthe wavelength, the higher the refractionangle, giving diverse colors different focalpoints. For example, the difference betweenblue and red light can be up to 2 diopters. Asa result, the image can look blurred or havenoticeably colored edges.

THE NEXT GENERATION OFBLUE LIGHT BLOCKING LENSES

ZEISS BlueGuard is an in-material blue lightblocking solution that addresses the complexchallenges of balancing blue light’s positiveand negative side and is available with ZEISSDuraVision Platinum coating. It blocks up to40 percent of the blue-violet spectrum¹⁴, 400to 455 nm while transmitting beneficial wavelengths 455 to 500 nm. By blocking blue lightin the material, ZEISS BlueGuard reducesdigital blue light reflections up to 50 percentcompared to typical blue light coatings.¹⁵

ZEISS BlueGuard uses the latest benzotriazole and benzophenone-based lens chemistryto support UV and blue light absorption, delivering excellent color fidelity and spectral coverage. In addition, the ZEISS 1.50 index BlueGuard material uses state-of-the-art pigments tobalance clarity and protection perfectly. ZEISSuses its global network to deliver ZEISS BlueGuard materials for all standard plastic lenses,indexes 1.50 to 1.74.

ZEISS BLUEGUARD LENSES BLOCK UP TO 40 PERCENT OF POTENTIALLY HARMFULBLUE LIGHT

As measured by BVB, ZEISS BlueGuard Lenses block up to 40 percent of potentially harmful blue light.¹⁴ All ZEISS BlueGuard materials offer similar BVB levels, from 38 percent to42 percent (Fig. 6) and are available in 1.50, 1.56, 1.60, 1.67, 1.74, Trivex® (1.53) and Polycarbonate (1.59) in many regions.

TOTAL UV PROTECTION TO 400 NM

International regulatory bodies agree that UV isharmful to the human eye and surrounding tissues. Ultraviolet radiation ranges between 100 to 400 nm. While UV is invisible, it can stilldamage eyes and other structures.

In addition to partially blocking potentially harmful blue light, ZEISS BlueGuard Lenses provide complete UV protection, blocking harmful UV radiation up to 400 nm. This pro tection is standard for ZEISS UVProtect andZEISS BlueGuard Lenses.

THE DIGITAL BLUE LIGHTREFLECTION METRIC

During video calls, lenses with blue-blockingcoatings show annoying blue and violet reflections. ZEISS BlueGuard lenses provide superiorin-material blue light blocking, reducing bluereflections from the front surface of the lens byup to 50 percent over coatings (Fig. 7).

DBR_LED calculates the intensity of blue lightreflected by the lens front surface seen by thehuman eye when the light source is the commonly emitted spectrum from digital screens.In the absence of industry or scientific standards to measure this effect, ZEISS developedthe DBR_LED metric. Most digital displays produce peak intensity between 380 and 500nm. Therefore, ZEISS used the display spectrum for the world’s most popular smartphonein the DBR_LED calculation.

Based on digital blue reflectance (DBR_LED),ZEISS BlueGuard Lenses exhibit up to 50 percent less digital blue light reflection thanZEISS DuraVision BlueProtect.

• R(λ) is the spectral reflectance of the front side of the spectacle lens.

• L(λ) is the Luminous efficiency function for a 10° observer (www.cvrl.org/ciepr.htm- CIE 2006).¹⁶

• LED(λ) is the spectral distribution of the most popular smartphone of the world 2020^[17]

• Because blue light is blocked in-material, ZEISS BlueGuard is ideally combined with ZEISS DuraVision Platinum UV coating—the premium AR coating with outstanding anti-reflective qualities throughout the visible spectrum.

A ZEISS quantitative survey found that 72percent of participants felt ZEISS BlueGuardLenses showed less intense reflections thanZEISS DuraVision BlueProtect.¹⁸

OUTSTANDING CLARITY AND HIGH TRANSMISSION

Previous in-material blue light lenses showed discolorations from grey/blue color additives, reduced lens transmittance and a grey or bluish hue.

ZEISS chemists have found the best balancebetween clarity and transmission. ZEISS BlueGuard Lenses are engineered to achieve thebest clarity and achieve up to 97.8 percentluminous transmittance.¹⁴ As a result, 90 percent of wearers are very satisfied with the clarityof ZEISS BlueGuard Lenses.¹⁸

COMPARING ZEISS BLUE GUARD LENSES TO ZEISSDURAVISION BLUEPROTECT

The most significant difference between ZEISS BlueGuard Lenses and ZEISS DuraVision BlueProtect is the blue-blocking approach—absorptionversus reflection. ZEISS BlueGuard Lenses have anin-material solution in which the blue light isabsorbed. ZEISS DuraVision BlueProtect uses acoating, reflecting the light. As a result, ZEISSBlueGuard Lenses are designed to deliver moreprotection with less reflection and better clarity.

CUSTOMER ACCEPTANCE

In an external consumer acceptance study¹⁹conducted by ZEISS, 182 participants testedZEISS BlueGuard Lenses compared to theirhabitual lenses. Almost 6 out of 10 (59.6percent) of the study participants werealready experienced wearers of various bluefilter lenses. The feedback:

• Result 1: 96 percent (9 out of 10) of spectacle lens wearers are satisfied with the clarity of ZEISS BlueGuard lenses.

• Result 2: 93 percent (9 out of 10) of wearers say they feel less digital eye strain with ZEISS BlueGuard lenses.

• Result 3: 92 percent (9 out of 10) of lens wearers state they experience fewer symptoms, including tired eyes, with ZEISS BlueGuard lenses.

THE SOLUTION:
ZEISS BLUEGUARD LENSES

• Designed to address digital eye strain by blocking short-wavelength blue light.

• Blocks up to 40 percent of potentially harmful blue light.

• Complete UV protection up to 400 nm.

• Beneficial blue light transmits.

• In-material blue-blocking solution reduces

unwanted digital blue light reflecting off the lens surface by up to 50 percent compared to typical blue filter coatings.

• Optimally balanced for clarity and protection.

ZEISS BlueGuard lenses are a new class ofblue filter lenses that offer your patients moreprotection and less blue light reflections.