Closing the UV Protection Gap
Ophthalmic Lens Standards vs. Biological Protection Requirements
By Deborah Kotob, ABOM
Release Date: July 1, 2018
Expiration Date: August 1, 2019
Upon completion of this program, the participant should be able to:
- Learn about the current gap between UV protection standard guidelines for spectacle lenses versus the standard definition of the UV hazard range.
- Increase understanding of the importance of preventing the acute and chronic effects of UV exposure to the eye and surrounding skin.
- Raise awareness of the amplified risk that UVR exposure poses to children's eyes.
- Learn about a new sunglass level UV protection in clear lenses that is now available in Zeiss UVProtect clear lenses.
This course is approved for one (1) hour of CE credit by the American Board of Opticianry (ABO). Technical Level 2 Course STJHI692-2
This course is supported by an educational grant from CARL ZEISS VISION
We can all agree on the importance of protecting our eyes and our children's eyes from harmful light. And as eyecare professionals, our concern is to always recommend lenses with the highest level of protection for the patient.
In this course, we will refocus the "prevention for protection" message on the necessity to reduce ultraviolet radiation (UVR) exposure to our eyes. And we'll discuss the fact that even clear ophthalmic lenses regardless of material should have sunglass level UV400 protection.
Many of you may be surprised to learn that 80 percent (4 out of 5) of clear ophthalmic lenses sold today do not provide complete UV400 protection. Zeiss identified this concern, and they address it with their new UVProtect lenses that provide sunglass level UV protection across all of their lens materials.
The UV eye damage concern is soundly established on science, but it has been lost of late as our focus has shifted to blue light emissions from digital device screens. Claims that blue light can have deleterious effects on our eye health and can produce eye fatigue or cause circadian rhythm disruption have consumers and opticians alike in a state of alarm. Though the blue light emissions from digital device screens warrant discussion, we need perspective; we must not lose sight of the real and known threat (solar UV, up to 120,000 lux) while we debate a small potential new risk (digital screen blue light up to 150 lux).
I'm not saying that we shouldn't concern ourselves with blue light coming off of screens. We should lower the levels of all known and even potentially damaging light. But our primary focus should be on the highest known proven threat: solar UV radiation. We don't have to debate if UV is harmful to the eye, the link between ocular UV exposure and eye disease and disorders is rooted in science-based evidence that is broadly accepted by the research and medical communities. Very important: Science alerts us to the fact that children are in the highest risk category for UV damage because their young eyes have not developed the natural increase in protection of an adult lens.
Now that our focus is back on the UV hazard to the eye, let's review how UV damages the eye and how we serve the patient best when we provide sunglass level UV 400 nm protection in their clear ophthalmic lenses.
Why is it essential to start UV protection young? UV damage can result in permanent harm to our eye beginning with first exposure in youth and adding up over a lifetime. Children receive upwards of 50 percent of their lifetime UV exposure before the age of 18. (Stern et al., 1986)
A higher level of UV protection in clear lenses would benefit us all but especially the most vulnerable among us—children. UV-related chronic eye diseases manifest later in life, but the damage begins and accumulates rapidly in our youth.
Zeiss believes that our dress pair of eyeglasses should have clear lenses with the same level of UV protection as required in premium UV400 nm sun lenses. They are convinced that this level of protection is essential for all eyes, but especially those of our children.
As eyecare professionals, many of us have been led to believe that when lenses claim 100 percent UV protection, this always means full UVA/UVB protection. But in this course, we will learn that all too often this is not the case, and we will discuss the need for providing sunglass level UV protection in all of our clear eyeglass lenses.
In this course, we will discuss the risk of UV exposure to the eye and the need for clear eyeglass lenses that provide a higher level of protection than the current standard. And we'll review the three levels of ultraviolet radiation (UVR) and the deleterious effects UVR has on our eyes and surrounding skin. We will learn how Zeiss UVProtect lenses raise the UV protection level in all Zeiss clear lens materials to sunglass-level UV400 protection without compromising the clarity or aesthetics of the lens.
WHAT IS THE UV PROTECTION STANDARD GAP?
The UV protection standard gap is the difference between the ANSI/ISO spectacle lens UV protection requirement of 380 nm and the ISO referenced ICNIRP UV Hazard definition that caps UVR at 400 nm. The difference between the two represents a 20 nm gap which accounts for 40 percent of solar UVR exposure (Fig. 1).
Having worked for a lens manufacturer myself for over 10 years, I was surprised to learn that 100 percent UV protection does not mean 100 percent UV400 protection. My assumption was wrong, as I discovered current standards only require 100 percent up to UV380 nm protection.
The most sold lens materials in the market: 1.5, 1.60 polycarbonate, and some 1.67 materials do not block up to 400 nm (Fig. 2). However, ophthalmic lens manufacturers who meet the current standards can claim 100 percent UV protection, while lacking protection for up to 40 percent of the most plentiful and potentially harmful UV radiation incident upon our eyes and surrounding skin.
Scientific and health communities and the International Commission on Nonionizing Radiation Protection (ICNIRP) place the UV hazard upper range at 400 nm. The World Health Organization defines UV as ending at 400 nanometers, and they recommend UV400 eye protection. Furthermore, the Australia/New Zealand sunglass standard (AS/NZS 1067:2003. Australian/New Zealand Standard sunglasses and fashion spectacles) considers UVR up to 400 nm.
In defense of the current ANSI/ISO UV380 nm standard in ophthalmic spectacle lenses, at the time that the standard for ophthalmic lenses was set, the production of clear lenses with UV400 protection was not yet possible. To make this point, many of you may remember years ago when UV400 polycarbonate lenses were available, but they had a distinct yellow hue. We did not sell many because they were unattractive. The old version of polycarbonate UV400 lenses illustrates why it was hard to have a product that protected up to 400 nm. If your patients rejected cosmetically unattractive lenses then, regardless of the increase in protection, then the stated mission of increasing protection was not accomplished.
Cosmetics and saleability was just one issue that potentially impacted the UV upper range classification for ophthalmic spectacle lenses at the time. The other issue lay in difficulty to define where UVR ends, and visible light begins on the electromagnetic spectrum. There is an overlap of the wavelengths that fall within the UV hazard range (ending at 400 nm) and those wavelengths that are capable of producing a visual response. In children and young adults, UVA rays as short as 365 nanometers can generate a visual response, meaning that these dangerous rays reach the retina. Gurrey RK, Ham WT, et al., state that the retina is six times more susceptible to UV damage than it is from visible light (traditionally defined as 400 nm to 750 nm). As the patient's trusted eyecare professional, shouldn't we be erring on the side of higher levels of protection in clear lenses? And shouldn't we be starting this protection at an early age to protect young children?
Thankfully, the cosmetic issue is solved, and now you can confidently recommend clear, cosmetically attractive lenses to your patients with sunglass level UV400 nm protection with UVProtect lenses.
Why is it important to close the UV protection gap in clear ophthalmic spectacle lenses? Eye health is too important to risk. UV damage is a 365-day yearround threat. No matter the season or if conditions are sunny or cloudy, UV radiation is always an invisible danger to the eyes and skin. We tend to understand the risk of UV exposure to our skin, or at least we know the most common effects, e.g., skin cancer, premature aging and sunburn. However, we know less about the threat to the eyes. Over time, exposure to UV rays can cause various forms of eye disease and can accelerate aging by damaging the sensitive skin around the eyes.
Consider these key facts: Children receive upwards of 70 percent more UV to their retina and as a study by Mueller HA, "Light Toxicity in the Posterior Segment" in 1982 reports, the retina is up to six times more damaged by UV radiation than visible light.
A child's retina is more exposed to UV because they have larger pupils than adults and clear crystalline lenses allowing higher transmission of harmful UV rays. Gilliard et al. state that the "Young lens transmits 300 to 340 in UVB range max 8 percent 320 nm."
Joan E. Roberts, Ph.D. states in "Ultraviolet Radiation as a Risk Factor for Cataract and Macular Degeneration" that "Both ultraviolet-A (UV-A) and UV-B induce cataract formation and are not necessary for sight. Ultraviolet radiation is also a risk factor for damage to the retinas of children. The removal of these wavelengths from ocular exposure will significantly reduce the risk of early cataract and retinal damage. One way this may be easily done is by wearing sunglasses that block wavelengths below 400 nm (marked 400 on the sunglasses)."
Dr. Roberts recommends sunglass UV400 level protection, but how many children own sunglasses let alone wear sunglasses outdoors to protect their eyes from UV radiation? According to The Vision Council's VisionWatch, only 7.6 percent of parents report that their children always wear sunglasses outdoors. These low rates of sunglass wear for children make it all the more critical that they have sunglass level UV 400 protection in their clear general purpose eyewear.
The World Health Organization states the following regarding the importance of UV protection: "Among adults, only small amounts (1 percent or less) of UV reach the retina because of absorption by the cornea and lens. However, because UV is known to damage tissue, the importance of this small amount as a cause of retinal damage cannot be ignored. It has been suggested that age-related macular degeneration (a loss of central vision) is associated with light exposure. This disease is a common cause of untreatable blindness in the developed world."
WHAT IS UV RADIATION (UVR)?
For the average person, our daily activities do not expose us to artificial sources of UV radiation. Therefore, the majority of UV exposure for most of us comes from the sun and not just sunlight directly reaching our eye but much from scattered and reflected sunlight (Fig. 3). UVR exposure is highest on clear days, at higher elevations and close to the equator but it is present everywhere, every day of the year even on cloudy days, and in conditions where a high degree of reflection is occurring such as off of the snow, eye injury such as photokeratitis can occur. Most of us have witnessed cases of photokeratitis aka snowblindness. Increased exposure factors include:
- Time of year: summer exposure higher.
- Altitude: UV exposure rate rises 10 percent with every 1,000 foot increase in elevation.
- Latitude: UV exposure most potent at the equator.
- Thin clouds and haze: don't provide a significant degree of UV protection and can actually increase exposure through scatter of UV rays.
UVR consists of the highest energy wavelengths absorbed by the human biological tissue. The various structures of our eyes absorb different bands of UV wavelengths. The transmission of UVR to the retina varies with age. In the young, the crystalline lens has not developed the protective UV absorbing proteins and chromophores of an adult lens. Therefore, their eyes are at a higher risk of UV reaching and harming their retinae.
UVR consist of three bands—UVA, UVB and UVC:
UVC—100 to 280 nm, is absorbed in the earth's ozone layer in the stratosphere although the hole in the ozone layer that appears over Antarctica seasonally and does allow some UVC through, and is being closely monitored to determine the effects on ocean, plant and animal life.
UVB—"280 to 315 nm, falls within the UV-B part of the electromagnetic spectrum, UV-B causes damage at the molecular level to the fundamental building block of life—deoxyribonucleic acid (DNA)," according to Jeannie Allen, author of "Ultraviolet Radiation: How It Affects Life on Earth." (Retrieved from earthobservatory.nasa.gov/features/UVB)
Less than 1 percent of UVB reaches the earth's surface. You may have learned to associate the "B" in UVB with a burn. It is also a strong contributor to photochemical damage to the skin along with premature aging and malignant changes. Our anterior eye layer of the cornea absorbs most UVB providing a level of protection for the iris, lens and retina. Small amounts make it through to our lens and our retina under average light levels. However, even more make it through when the level of exposure is excessive, overwhelming our eyes' natural defense mechanisms. Moreover, the young have a broader band of UVR reaching their retinae, including the higher energy UVB band which puts their retinae at a higher risk for damage.
UVA—315 to 400 nm, represent 99 percent of the UVR reaching the earth's surface and is the most prominent UVR that our eyes and skin absorb. It penetrates deep into the layers of our skin and eyes. The current gap in UV protection in ophthalmic lenses is within the UVA range.
We all understand, although we probably take for granted, that ultraviolet radiation is essential to life on this planet. On the other hand, UVR is high energy capable of producing damaging chemical reactions in living tissue. Therefore, we must protect ourselves by avoiding too much exposure. The human race would cease to exist without oxygen, the byproduct of plant photosynthesis. Plants need ultraviolet radiation UVR for photosynthesis so that they can grow and bear flowers, fruit and seeds. Humans need UV to synthesize the essential vitamin D.
However, ultraviolet radiation provides no benefit to the eyes and does not contribute to sight. With a few simple protective measures such as sunscreen for the skin and sunglass level UV400 protection for the eyes, we can enjoy UVR's benefits and avoid its harmful effects.
How does UVR (actinic rays) cause damage to our eyes and surrounding skin?
Photodamage—There are three mechanisms by which light can damage the eye: photothermal, photomechanical and photochemical. Ultraviolet radiation damage to the eye is photochemically induced, meaning that actinic high energy light produces a photochemical reaction in our skin and eye tissues that can result in a permanent injury which is cumulative and irreversible in nature, providing yet another good reason to start protection young. The risk of UVR damage is amplified in the presence of some drugs and medications as well. Certain medical conditions can create an environment that increases the harmful effects of UVR exposure such as diabetes. When eye damage including retinal damage is irreversible, preventative measures to avoid photodamage become an essential element of eyecare.
The World Health Organization (WHO) lists the following potential acute and chronic effects of excess UV exposure to the eye:
Acute: acute photokeratitis and conjunctivitis; acute solar retinopathy (from staring at the sun—occurs most often when viewing a solar eclipse without proper lenses).
Chronic: climatic droplet keratopathy; pterygium; pinguecula (benign permanent unsightly growth can affect normal tear film distribution and interfere with contact lens wear); squamous cell carcinoma of the cornea and conjunctiva; cortical cataract; ocular melanoma; macular degeneration.
Note: None of these conditions result from viewing a smartphone, tablet or computer screen. We must make sure that patients understand that the danger comes from the sun and UV exposure.
The areas of the eye impacted by UV are both age and wavelength dependent. The illustration below shows the wavelengths absorbed by each layer of the adult eye (Figs. 4a and 4b). A child's retina is exposed to upwards of 70 percent more UVR than an adult eye.
Don't forget about the UV hazard to the delicate skin surrounding the eye.
Eyelids and periorbital skin: UVR damage to the eyelids is common. The eyelids are a troublesome area because applying sunscreen can be irritating to the eyes.
Skin conditions induced by UVR include:
- Photo-aging of the eyelids: Long wavelengths of UVR penetrate into the deepest layer of the skin-damaging collagen and elastin. The result is thickening and wrinkles.
- UVR damage to sebaceous glands: can lead to xerosis (dry skin).
- Actinic keratosis: typically pre-cancerous—it is an advanced type of skin damage with dry red patches.
- Skin cancers of the eyelid: Eyelid cancers account for 5 to 10 percent of skin cancers and because of the local anatomy can easily spread (metastasize) to other parts of the body.
Many of us would argue that we always recommend sunglasses for UV protection outdoors. Fact: Quality polarized sunglasses are an excellent choice for outdoor protection from UV, but studies show that only 1 in 4 people consistently wear sunglasses outdoors. Another VisionWatch survey of 10,000 adults age 18 and older found that only 31 percent reported wearing sunglasses all the time outdoors, and they reported that the percentage of their children who wear sunglasses all the time is only 7.6 percent. Knowing the low rate of sunglass usage outdoors makes it critical that our clear dress pair of lenses provide sunglass level protection.
According to studies by Glickman et al., UVR transmission to the retina varies with age. A child's retina receives upwards of 70 percent more UVR than an adult. Research indicates that babies are virtually defenseless against the higher dose of UV their eyes experience due to their large pupils and crystal clear lenses combined with deficient antioxidant protection levels, according to Billy Hammond et al., ("Oxidative Photodegradation of Ocular Tissues: Beneficial Effects of Filtering and Exogenous Antioxidants").
As eyecare professionals, it is important that we raise our patient's awareness of these facts. Protection from UVR for both the skin and the eyes should start with babies who are the most exposed and defenseless. Also, remember that we need to protect our anterior and posterior eyes from these high energy wavelengths to avoid damage to ocular cells, which in the case of the crystalline lens results in cataract development.
Consumers don't fully understand the risk posed by UV to their eyes or their child's eyes. The following excerpt is from a new consumer survey released by Zeiss: "Consumers are significantly uninformed regarding the impact of UV on the eyes. Less than 10 percent of consumers are aware that cataracts are directly attributable to overexposure to UV, and only 13 percent are aware that skin cancer around the eyes is a potential side effect. However, 87 percent of glasses wearers would consider purchasing clear lens eyeglasses with UV protection if an option was available. Among parents, only 3 percent of parents are aware that 50 percent of eye damage from UV radiation occurs before the age of 18, and less than 10 percent are aware that children's eyes are exposed to three times the UV radiation compared to adults."
Nothing illustrates the point better than seeing evidence of UV damage. In Fig. 5, the UV camera reveals UV skin damage that is invisible to the naked eye. Only two parts of our body absorb UV, making them susceptible to UV radiation damage—the skin and the eyes. A UV camera photo of a UVProtect lens shows it as black because all UVR is blocked by the lens.
SHARING INNOVATION FOR THE GREATER GOOD
Zeiss UVProtect lenses employ new lens manufacturing technology that provides sunglass-level protection (UV400) in all of their clear lens materials.
It is cast into the lens, then molded into all Zeiss clear lens materials, meaning that the UV protection will be consistent and controllable, and will last longer than traditional methods of applying UV tints or coatings. Zeiss has adopted the strict Australia/New Zealand sunglass standard for its UVProtect clear lens materials. By that standard, each of these materials transmits less than 0.4 percent solar UVR, in a clear and cosmetically attractive lens. Moreover, they are providing this added level of protection in all of their clear lens materials at no additional charge.
Zeiss is a 100 percent foundationowned company with a 170-year history of innovation in the optical industry. Their belief in the importance of raising the UV protection level industry-wide is so strong that they intentionally choose not to patent their UVProtect technology and are actively encouraging others to join them in raising the standard of care. They envision a future where UV protection in all clear lens materials manufactured provide up to sunglasslevel UV400 protection.
Our patients place their trust and confidence in us. We owe it to them to provide the highest level of protection available, especially when chronic UVR exposure is universally known to be harmful to our eyes.