Recent Blog Articles
Taking up adaptive sports
Cutting and self-harm: Why it happens and what to do
Discrimination at work is linked to high blood pressure
Pouring from an empty cup? Three ways to refill emotionally
Give praise to the elbow: A bending, twisting marvel
Sneezy and dopey? Seasonal allergies and your brain
The FDA relaxes restrictions on blood donation
Apps to accelerometers: Can technology improve mental health in older adults?
Swimming and skin: What to know if a child has eczema
A muscle-building obsession in boys: What to know and do
Diseases & Conditions
Choosing the right sunglasses
The easiest way to protect your eyes from the sun's hazardous radiation is to wear sunglasses, not only in the summer months, but year-round. Ultraviolet (UV) light can damage the iris, retina, lens, and cornea, leading to permanent vision loss. It's a good idea to request UV protection (an invisible coating) on all of your prescription glasses.
UV light has three wavelengths:
UVA is long, looks almost blue in the visible spectrum, and is responsible for skin tanning and aging. It may also contribute to skin cancer risk.
UVB is shorter and more energetic, and it's linked to sunburn and skin cancer. A large portion of UVB light is absorbed by the atmosphere's ozone layer.
UVC is short. It is completely absorbed by the ozone layer.
Sunglasses are labeled according to guidelines for UV protection established by the American National Standards Institute (ANSI). There are three categories:
Cosmetic. These lightly tinted lenses are good for daily wear. They block 70% of UVB rays, 20% of UVA, and 60% of visible light.
General purpose. These medium to dark lenses are fine for most outdoor recreation. They block 95% of UVB, 60% of UVA, and 60% to 90% of visible light. Most sunglasses fall into
Special purpose. These are extremely dark lenses with UV blockers, recommended for places with very bright conditions, such as beaches and ski slopes. They block 99% of UVB, 60% of UVA, and 97% of visible light.
Just because a lens is expensive or appears darker doesn't mean that its ability to block out UV radiation is any greater than that of a cheaper or lighter lens. Look for the ANSI label. Even inexpensive sunglasses can be protective.
There is some evidence that blue light from the sun may contribute to the development of age-related macular degeneration. Lenses with a red, amber, or orange tint may provide better protection against this light. You may find less distortion, however, with gray or green lenses.
If you aren't sure what kind of sunglasses to buy or think you may be at high risk for eye disease, ask an eye care professional for a recommendation.
For more information about keeping your eyes healthy, read The Aging Eye, a Special Health Report from Harvard Medical School.
Image: Zinkevych/Getty images
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Free Healthbeat Signup
Get the latest in health news delivered to your inbox!