In the cloudy winter months, it’s difficult to imagine the sun’s rays as anything but a welcomed change. But did you know the sun’s rays can also be harmful to your eyes? Ultraviolet light produced by sunlight is responsible for several vision problems, including snow-blindness, cataracts, and numerous degenerative eye conditions. The best way to protect yourself from these harmful effects is to always wear eye protection.

Ultraviolet light is light beyond the spectrum of light that is visible to the human eye, similar to x-rays or infrared light. It comes in three forms: UVA, UVB, and UVC. Earth’s atmosphere filters out almost all UVC and much of the UVB light, meaning the majority of UV rays we encounter are UVA. Indeed, UVA is in part beneficial to human beings, as it is required source for vitamin-D production in the skin. However, overexposure to any or all UV rays can lead to advanced aging, skin cancer, or just good old sunburn.

When it comes to your eyes, however, UV rays are very damaging. Most eye care professionals recommend wearing sunglasses whenever you are going to see a prolonged exposure to UV rays. And, since UV rays penetrate our atmosphere even on the cloudiest days, having proper eye protection is always a must. It’s difficult to believe that light we can’t see can be damaging to our eyes, but UV rays, whether directly from the sun, or even by reflection, pose a significant risk to our vision.

The peak hours for UV ray penetration are between 10 AM and 3 PM, when the sun is at its apex. Other factors increase risk, as well. Due to their unique atmospheric qualities, higher altitudes and locations closer to the equator see higher UV levels. You should consider all these factors when you know you have to be out in the sun for an extended period.

But, since most of us don’t really have a choice regarding sun exposure – after all, most of us don’t live and work in caves – having proper eye protection is vital. When choosing sunglasses, make sure they guarantee UV protection up to 98% (or to 400nm). Glass is largely transparent to UV rays, so plastic or composite lenses tend to be a better choice. If your glasses have been coated in a UV filter material, they are even safer.

No matter what time of year, UV rays are always present. Although they tend to penetrate the atmosphere more during the warm summer months, they are also a risk during winter. Snow reflects UV rays, essentially letting them do twice the damage. Being aware of the risks of UV exposure is the first and most important step to protecting your eyes. But, with quality protective eyewear year-round, you can enjoy the warm, healthy sunshine carefree.