Guide to Your Sunglasses’ UV Protection

What is UV Light

Sunburn and eye damage from the sun are caused by UV radiation. The sun is our main source of UV rays and produces 3 different types of UV rays: UVA, UVB, and UVC

 UVA:

95% of the radiation that reaches the surface of the earth. Causes wrinkles, sun spots, skin aging, and is linked to skin cancer. Damages central vision.

UVB:

Causes sunburn and is strongly linked to development of skin cancers. Damages the cornea and lens of the eye.

UVC:

Highest energy form of UV rays. UVC from the sun is completely absorbed by the earth’s atmosphere, so exposure comes only from artificial sources such as UV lamps and lasers.

The intensity of these rays is measured through the UV index, which differs depending on factors such as the season, time of day, altitude, and geographic location. You can check the daily UV index for your city online or on a weather app.

How Does UV Radiation Affect Your Eyes?

Short-term exposure to UV light can cause temporary damage to the eyes, but long term exposure over the course of years can lead to chronic, progressive eye diseases:

1. Cataracts:
   1. Cataracts are characterized by a fogging/clouding of the eye’s lens. The fogging inhibits the eye’s ability to focus light and leads to progressive vision loss. The condition is often described as looking through a foggy window. UV light can damage proteins in the lens and can accelerate formation of cataracts.
2. Macular Degeneration:
   1. Macular Degeneration (AMD) is a progressive disease caused by damage and deterioration of the macula, a small central portion of the retina. Symptoms include central vision loss – you will lose the ability to see small details straight-on, but your peripheral vision will be unaffected. AMD is the leading cause of vision loss in people over the age of 50, and exposure to UV rays may contribute to AMD.
3. Pterygium
   1. Also known as “surfer’s eye”, pterygium is characterized by non-cancerous growths of tissue on the conjunctiva, the clear membrane that covers your eye and lines your eyelids. The growth is not always accompanied by other symptoms but can often become a cosmetic concern.
4. Photokeratitis
   1. Often compared to a sunburn of the eyes, photokeratitis refers to short-term, temporary damage to the cornea and conjunctiva caused by exposure to UV rays. The condition is referred to as “snow blindness” when the UV rays are reflected by snow or ice. Symptoms can include headaches and light sensitivity, pain and swelling of the eye, and visual aberrations/blurring.

Tint vs UV Protection

Contrary to popular belief, not all sunglasses protect you from UV rays. You may think that your darkest tinted pair of sunglasses offer the highest level of UV protection, but the tint of the lens has zero correlation with the UV protection provided; even some clear lenses can block almost all UV light.

The tint of the lens simply affects how much visible light we can see. As shown in our bluelight (add a hyperlink here) post, visible light and UV light are both forms of electromagnetic (EM) radiation on the EM spectrum, but the human eye cannot see UV rays. A lighter colored lens will simply offer a lighter colored image and a darker lens will offer a darker colored image.

This is where the CE mark on your sunglasses comes into play. The CE (European Conformity) stamp means that the product passes the European Union’s health, environment, and safety standards.

CE lists five different categories for sunglasses, ranging from Category 0 – Category 4. Each category is measured by a VLT % (Visible Light Transmission), which measures the percentage of visible light that passes through the lens: a higher category means that less light passes through the lens.