To perform this test, you need to gather a few materials in addition to the glasses you intend to test. You need a UV flashlight, also known as a handheld black light, and an object that has built-in security features that are only visible under UV light, such as a credit card or a banknote. Bills of any denomination should work. Before looking at the lenses, perform a control test to verify that your light is a UV light and that security features are present. Shine your UV flashlight on the bill. When the light touches the UV-sensitive security features, they should come into view. They should no longer be visible when you move the light away. Hold the frames between the UV flashlight and the bill so that the light shines through the lenses. If the security features remain invisible, the lenses are effective at blocking UV light from the sun. If the security features do show up, your lenses let some of the UV rays through. This means that they do not provide adequate sun protection and should not be worn outside. Dark sunglasses reduce the amount of light that reaches your eyes, causing your pupils to dilate. If the lenses do not also provide UV protection, dilation allows more UV radiation to enter your eye. It can be worse than wearing nothing on your face at all. Light lenses of prescription sunglasses do not cause your pupils to dilate as much as dark lenses do. However, if the lenses provide UV protection, it is a matter of personal preference. UV protection can be added to light-colored lenses or lenses with no color at all. In the short term, exposure to UV radiation can cause your eyes to get sunburned. In the long term, it can cause benign or cancerous growths on the eye. It can also put you at risk for other chronic ocular conditions, such as macular degeneration and cataracts. Polarized lenses block horizontal light rays to reduce glare. This prevents you from having to squint when looking at an object from which sunlight is reflecting. Polarization itself does nothing to block UV rays, but there are polarized lenses that also provide UV protection. Be sure to verify before purchasing. As with polarized lenses, it is not a given that dark polarized sunglasses with prescription lenses will automatically protect your eyes from UV radiation. However, UV protection is usually an option with dark prescription lenses, so this is something to verify and specifically ask for when ordering.
1. Gather Your Materials
2. Set a Baseline
3. Shine the Light Through the Lenses of the Sunglasses and Onto the Bill
FAQs
What happens if you go outside wearing sunglasses that don't provide UV protection?
Which are better: Dark lenses or light lenses?
How can UV radiation damage your eyes?
Do polarized sunglasses provide UV protection?
Do prescription sunglasses provide UV protection?
