Types of Ultraviolet Radiation
Ultraviolet, or UV, light exists just above visible light on the electromagnetic spectrum and can be incredibly harmful to your eyes. There are three different types of UV radiation: UVC, UVB, and UVA.
UVC radiation is the highest energy rays and can potentially cause the most damage to your eyes and skin. However, Earth’s ozone layer protects us by blocking almost all UVC radiation. Unfortunately, this means that the ongoing depletion of the ozone layer could potentially allow more of these high energy UVC rays to reach the surface of the Earth and cause serious UV related health problems. UVC rays have wavelengths between 100 and 280 nanometers (NM).
UVB rays have slightly longer wavelengths then UVC rays, with wavelengths between 280 and 315 nm. This means they are also lower energy waves then UVC radiation, and are partially filtered out by the ozone layer. However, some of these rays are still able to reach the Earth’s surface.
Low doses of UVB radiation stimulate our skin cells and cause them to produce more melanin, which is the pigment that colors our skin. This causes our skin to darken, a phenomenon we call a suntan. However, higher doses of UVB radiation can cause sunburns, and increase our risk of developing skin cancer. Prolonged UVB radiation exposure can also cause our skin to wrinkle, discolor, and prematurely age.
UVA rays are the closest of the UV wavelengths to visible light on the electromagnetic spectrum and are lower energy than both UVC and UVB rays. However, UVA rays are able to pass through our corneas and reach both the lenses and the retinas in our eyes. Excessive exposure to UVA radiation can cause certain types of cataracts, and may also play a role in the development of macular degeneration.
Other Radiation Risks Besides UV
HEV Radiation (High-Energy Visible Radiation) refers to blue light on the visible light spectrum. HEV radiation has both longer wavelengths (400 to 500 nm) and lower energy than UV radiation, but it can still penetrate your eyes and cause retinal damage.
Lifestyle Factors to Take Into Account
Where you are, how high up you are above sea level, and what time it is all influence how much UV radiation you are exposed to.
- Geographic Location: Tropical areas near the Earth’s equator receive greater levels of UV radiation than areas near the poles. The farther away you are from the equator the less UV radiation you are exposed to throughout the day.
- Time of Day: The higher the sun is in the sky the more UV and HEV radiation you are exposed to. Radiation levels are highest between 10 am and 2 pm, so it is important during this window to be extra vigilant about UV protection.
- Altitude: We are exposed to more UV radiation the higher up we are.
- Setting: Wide open spaces, particularly those with highly reflective surfaces such as snow and sand, typically receive higher levels of UV radiation. Snow, in particular, is extremely effective at reflecting UV radiation, and the presence of snow can double your exposure levels. Urban settings are exposed to less UV radiation because tall buildings are able to shield the streets.
- Cloud Cover: Cloud cover, however, does not significantly shield you from UV radiation, and your risk of UV exposure can still be quite high on cloudy or overcast days. This is because UV radiation exists outside the visible spectrum of light, and can penetrate clouds.
- Medications: Some medications such as tetracycline, birth control pills, sulfa drugs, diuretics, and tranquilizers can make your body more sensitive to UV and HEV radiation. Individuals who are taking any of these medications need to be extra vigilant about monitoring and mitigating their UV exposure.
Individuals that spend a lot of time outside or are exposed to non-solar sources of UV radiation as part of their job should take extra precautions. These precautions can include:
- Engineering controls: These could include ensuring workers are working under opaque canopies or in the shade.
- Administrative controls: These could include rescheduling outdoor work so that it is not performed during the peak UV radiation period between 10 am and 2 pm, rotating workers between indoor and outdoor tasks, or moving outdoor tasks indoors when possible).
- Personal Protective Equipment (PPE): This could include wearing hats that shield the face, neck, and ears, wearing minimum SPF 15 broad-spectrum sunscreen, and wearing close fitting sunglasses that block at least 99% UV radiation.
- Training: Companies should ensure that all employees who are exposed to UV radiation as part of their work understand the risks associated with UV radiation exposure and know what steps they can take to limit their exposure in the workplace.
Prevent Age-Related Conditions and Cancer
UV radiation exposure can put you at risk for a variety of eye-related conditions including cataracts, macular degeneration, and eyelid cancer. One of the best ways to keep your eyes and eyelids safe is to invest in a good pair of UV blocking sunglasses, wear sunscreen on your face (including around your eyes), and wear a hat with a wide brim.
- Cataracts: Cataracts occur naturally as we age, but can be accelerated by excessive UV exposure. A cataract refers to a gradual clouding of the eye’s natural lens, resulting in vision loss. Though lifestyle changes may be enough to work around mild cataracts more advanced cases require surgery to restore your vision.
- Macular Degeneration: Macular degeneration (also called Age-Related Macular Degeneration, AMD, or ARMD) occurs when our macula begins to deteriorate. The macula refers to the small central area of your retina which is responsible for visual acuity.
- Eyelid Cancer: The thin tissue surrounding our eyes is particularly sensitive to UV radiation, making nonmelanoma cancers both on and around our eyelids common. Even individuals who regularly use sunscreen often forget to protect their eyelids.
Conditions Caused By UV Exposure
Photokeratitis (also known as Snow Blindness) is a painful, temporary loss of vision caused by overexposure to UV radiation, and is essentially a sunburn on your eye. Photokeratitis causes your cornea to become inflamed and can occur even if there is no snow present. Snow, water, and white sand are all extremely effective at reflecting UV radiation, which increases your exposure.
Photokeratitis can also be caused by radiation from man-made sources such as sunlamps and tanning booths.
By the time you realize you are suffering from photokeratitis, your eyes have already been exposed to too much UV radiation. Symptoms of photokeratitis include:
- Eye pain
- Red eyes
- A burning sensation in your eyes
- A gritty feeling in your eyes
- Foreign body sensation
- Watery eyes
- Blurry vision
- Sensitivity to light
- Swollen eyes and/or eyelids
- Glare and halos around lights
Vision loss from photokeratitis is typically temporary, and your normal vision should return within 24 to 48 hours.
Pingueculae are non-cancerous bumps on the eyeball that can cause corneal problems. These yellowish bumps are caused by a thickening of the conjunctiva on the sclera (white portion) of your eye. Pingueculae are most common amongst middle-aged and elderly individuals who have spent a lot of time in the sun. However, pingueculae can also occur in younger individuals and even children, especially if they spend a lot of time outdoors without sunglasses or hats to protect their eyes.
To decrease your risk of developing pingueculae it is important to wear UV blocking sunglasses outdoors, even if it is cloudy or overcast.
Symptoms of pingueculae include:
- Burning eyes
- Stinging eyes
- Itchy eyes
- Blurred vision
- Foreign body sensation
- Red eyes
If your pingueculae becomes swollen or inflamed it can progress into pingueculitis. Depending on how severe your symptoms are your eye care professional may be able to treat it with lubricating eye drops or scleral contact lenses (to cover the growth and protect it). However, more serious cases may require steroid eye drops or even surgery.
Pterygium (Surfer’s Eye)
Pterygia, also known as Surfer’s Eye, are wedge-shaped bumps on your eyeball that can cause disfigurement, discomfort, corneal problems, and blurry vision. Though this condition is sometimes called Surfer’s Eye you don’t need to be a surfer or spend time by the ocean, to get a pterygium. Anyone who is exposed to bright sunlight for long hours (especially near white sand, water, snow, or other highly reflective surfaces) are at an increased risk of developing a pterygium. If your pterygium progresses enough to invade your cornea it can cause astigmatism and higher-order aberrations and negatively impact your vision.
Though the primary cause of pterygium is UV radiation dry eye disease, dust, and wind can also cause pterygia to form. Individuals between the ages of 30 and 50 are more likely to develop pterygia, as well as individuals with light skin and light colored eyes.
Mild cases of pterygia may not have any symptoms, but individuals with more serious cases may experience:
- A gritty feeling in the eye
- A burning sensation
- Foreign body sensation
- Puffy, red eyes
Small pterygium may be treated with lubricants or mild steroid eye drops, but more serious cases will require surgery to correct. Regardless of how large your pterygium is it should be monitored carefully to prevent scaring, which can cause permanent vision loss.
Start Now, Children Included
Children, in particular, can benefit from learning how to protect themselves, and their eyes, from UV damage early on. As we age our eyes become exposed to more and more UV radiation, causing compounding damage. Good habits now can help your child reap the rewards of better eyesight later.
According to a study conducted by the Southern California School of Optometry, children are particularly sensitive to UV radiation, so extra precautions should be taken. Ensure your child wears sunscreen, has good quality UV protecting sunglasses and wears their hat when they play outdoors, even on cloudy or overcast days. Children tend to spend more time outside than adults do, which also increases their UV exposure. Sunglasses should be worn year round, especially if your child is playing outside in a highly reflective environment such as in the snow, by water, or on white sand.
Eyewear Protection for UV Rays
Sunglasses are something you should be wearing every time you go outside, even if it is cloudy or overcast. Though you may not be able to reverse the damage UV radiation might have already caused to your eyes you can limit future damage.
You should choose sunglass lenses that are able to block 100% of all UV radiation. Close-fitting, wraparound style frames with large lenses are best since they are better able to limit how much sunlight reaches your eyes and the area around your eyes. Your eye care professional will be able to answer any questions you have about your sunglasses and help you select a pair that is able to best suit your needs.
Photochromatic lenses, also called transition lenses or light-adaptive lenses, are a great way to protect your eyes from UV radiation. These lenses are clear when indoors, but tint automatically when exposed to sunlight. Photochromatic lenses can help you move seamlessly from indoor to outdoor environments without worrying about exposing your eyes to UV radiation.
Safety Glasses for Work
If you work outside or in an environment that exposes you to non-solar UV radiation you should make sure you have safety glasses that can protect you from UV radiation. Your eye care professional can help you select safety glasses that are able to suit your vision and UV protection needs. Even if you are not exposed to UV radiation as part of your job you should consider wearing safety glasses if you perform work that could put your eyes at risk.
Find the Right Pair with Help from Your Doctor
Finding the right pair of glasses for your vision and UV protection needs can be a daunting task, but it doesn’t have to be. Speak with your eye care professional about what to look for when shopping for sunglasses.