Protecting your eyes from solar radiation
The sun supports life on our planet, but its life-giving rays also pose dangers. The sun's primary danger is in the form of ultraviolet (UV) radiation. Artificial sources, like welding machines, tanning beds and lasers, can also produce UV radiation.
Most people are aware of how harmful UV radiation is to the skin. However, many may not realize that UV radiation can harm the eyes, and other components of solar radiation can also affect vision. There are three types of UV radiation. UV-C is absorbed by the ozone layer and does not present any threat. However, UV-A and UV-B radiation can have long- and short-term negative effects on the eyes and vision.
If your eyes are exposed to excessive amounts of UV radiation over a short period of time, you will likely experience photokeratitis. Like a "sunburn of the eye," photokeratitis can be painful. Its symptoms include red eyes, a foreign body sensation or gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. Fortunately, these symptoms are usually temporary and rarely cause permanent damage to the eyes.
The longer the eyes are exposed to solar radiation, the greater the risk of developing cataracts or macular degeneration later in life. It is not clear how much exposure to solar radiation will cause damage. Therefore, whenever you spend time outdoors, wear quality sunglasses that offer UV protection and a hat or cap with a wide brim. Also, certain contact lenses can provide additional UV protection.
To provide adequate protection for your eyes, sunglasses should:
- Block out 99 to 100% of both UV-A and UV-B radiation;
- Screen out 75 to 90% of visible light;
- Have lenses that are perfectly matched in color and free of distortion and imperfection;
- Have lenses that are gray for proper color recognition.
If you participate in potentially eye-hazardous outdoor work or sports, your sunglass lenses should be made from polycarbonate or Trivex® material. These lenses provide the most impact resistance. If you spend a lot of time outdoors in bright sunlight, consider wearing wraparound frames for additional protection from the harmful solar radiation. Don't forget protection for children and teenagers. They typically spend more time in the sun than adults.
Protecting your eyes from shorter-wavelength visible light
Chronic exposure to shorter-wavelength visible light (blue and violet light) may also be harmful to the retina. Many digital devices emit this shorter-wavelength visible light.
Blue light is part of the visible light spectrum. The sun emits blue light, as do artificial light sources, such as LEDs, computers and smartphones. Some types of blue light can be beneficial, helping us regulate our bodies' internal biological clocks.
However, blue-violet light can be harmful to the eyes, specifically the retina. It is a risk factor for the onset of age-related macular degeneration, a deterioration of the part of the retina responsible for sharp, central vision.
A recent study found that Americans spend almost 2 ½ hours on their tablets and smartphones every day. In addition, most offices and stores use fluorescent light bulbs, and LED lights are becoming increasingly popular.
Lenses that absorb harmful blue light but allow beneficial blue light through your lenses are entering the marketplace. You could also apply a special clear coating to traditional lenses to enhance their ability to block these harmful rays while you use computers and smartphones.
UV radiation checklist
If you can answer “yes” to one or more of the following questions, you could be at a higher risk for harm to the eyes from UV radiation:
- Do you spend a great deal of time outdoors?
- Do you spend time skiing, mountain climbing or at the beach?
- Do you use a sunlamp or tanning parlor?
- Do you live in the mountains or the U.S. Sunbelt?
- Are you a welder, medical technologist or do you work in the graphic arts or in the manufacture or electronic circuit boards?
- Have you had cataract surgery in one or both eyes?
- Do you take prescription or over-the-counter drugs that increase your sensitivity to UV radiation? (IF you are unsure, check with your doctor of optometry, pharmacist, or physician.)
See your doctor of optometry every year for a comprehensive eye examination. It is a good way to monitor your eye health, maintain good vision and keep track of your solar radiation protection needs, as well as advances in eye protection.
You probably know about the damage the sun's ultraviolet (UV) radiation can do to your skin. But do you know about the damage UV radiation can do to the eye?
This UV exposure adds up over time: The exposure while on the beach as a child combines with sun exposure as you age, in many cases resulting in problems later in life.
Most of the UV rays that pass through the pupil of the eye are absorbed by the crystalline lens of the eye. Over time, the cumulative effects of the UV radiation may cause cataracts in the lens of the eye.
Solar radiation also reaches the surface of the eye from above, below, and from the side. It is concentrated by the cornea, the clear front layer of the eye, on tissues located on the opposite side of the eye. This peripheral UV radiation, over years of exposure, may result in nasal or inferonasal cataracts and tissue elevations on the surface of the eye called pingueculae and pterygia.
The AOA recommends the use of sunglasses whose lenses absorb 99-100% of UV-A and UV-B rays. However, most sunglasses allow the peripheral UV radiation to reach the eyes from above, below and the side.
Some contact lenses also absorb UV radiation. As contact lenses fit directly on the eye, much of the UV radiation coming from above, below and the side is absorbed by these contact lenses. Thus, UV absorbing contact lenses are often recommended for those wearing sunglasses in high sun exposure environments.
The U.S. Food and Drug Administration has standards for UV-absorbing contact lenses based on the American National Standards Institute Z80.20 standards. There are two classifications of UV-absorbing lenses:
- FDA Class 1 absorber. Recommended for high exposure environments such as mountains or beaches. The lenses in this classification must absorb more than:
- 90% of UVA (316-380 nm wavelengths) and
- 99% of UVB (280 – 315 nm)
- FDA Class 2 absorber. Recommended for general purposes. These lenses must absorb more than:
- 50% of UVA and
- 95% of UVB
Wrap-around style sunglasses can further help prohibit UV radiation from reaching the eye from above, below and the sides.
Talk to your doctor of optometry about your outdoor activities in all seasons so that your risk of UV exposure can be assessed and the appropriate UV absorbing glasses and/or contact lenses prescribed for your individual needs.
Eye injuries in the workplace are very common. The National Institute for Occupational Safety and Health (NIOSH) reports that every day about 2,000 U.S. workers sustain job-related eye injuries that require medical treatment. However, safety experts and eye doctors believe the right eye protection can lessen the severity or even prevent 90% of these eye injuries.
Taking care of your health is critical and you may have concerns related to eye health as a result of the COVID-19 public health crisis. Doctors of optometry are resuming the delivery of comprehensive eye health and vision care and implementing new protocols to provide care in a safe and healthy environment.
Most people are aware of how harmful UV radiation is to the skin. However, many may not realize that UV radiation can harm the eyes, and other components of solar radiation can also affect vision.