Polarized, or anti-glare, sunglass lenses reduce light glare and eyestrain. Because of this, they improve vision and safety in the sun. When working or playing outdoors, you can become frustrated and even temporarily blinded by reflected light and glare. This is a potentially dangerous situation that polarization can prevent.
What Are Anti-Glare Glasses?
Usually light scatters because it bounces at varying angles off an object’s uneven surface. But if the surface is smooth, as with calm water or a flat piece of sheet metal, light reflects at one angle. When this light reflects right in your eyes, this is what we know as glare. Polarized sunglasses reduce glare and solve this problem.
How Polarized Lenses Work
Polarized lenses have a special chemical applied to them to filter light. The chemical’s molecules are lined up specifically to block some of the light from passing through the lens. Think of it like a miniblind hanging in front of a window. Only light that passes through the blind’s openings can be seen.
On polarized sunglasses, the filter creates vertical openings for light. Only light rays that approach your eyes vertically can fit through those openings. The lenses block all the horizontal light waves bouncing off a smooth pond or a shiny car hood, for instance.
As a result of this filtering, the image you see with polarized lenses is a bit darker than usual. But objects look crisper and clearer with polarized lenses, and details are easier to see.
When to Use Polarized Glasses
People who use polarized sunglasses often say they are less tired than usual after hours of battling sun glare. Polarized sunglasses can be a good choice for most everyday situations. These are some specific situations when polarized sunglasses may be especially helpful:
- Fishing. People who fish find that polarized sunglasses drastically cut the glare and help them see into the water.
- Boating. A long day on the water can cause eyestrain. You may also see below the surface of the water better, which is important if you are driving a boat as well.
- Golfing. Some golfers feel that polarized lenses make it hard to read greens well when putting, but studies haven’t all agreed on this issue. Many golfers do find that polarized lenses reduce glare on fairways, and you can remove polarized sunglasses when putting if that’s your preference. Another benefit? Though this would never happen to you, golf balls that find their way into water hazards are easier to spot when wearing polarized lenses.
- Most snowy environments. Snow causes glare, so a pair of polarized sunglasses are usually a good choice. See below for when polarized sunglasses may not be the best choice in snow.
When Not to Use Anti-Glare Sunglasses
There are a few instances where polarized lenses are not recommended.
- When looking at LCD (liquid crystal display) screens such as:
- car dashboard controls
- ATM cash machines
- cell phones
- some watches
- When glare or more light might be an advantage:
- to see ice on roads when driving
- to see icy patches when skiing
- when driving at night. You can buy polarized glasses that are supposed to help reduce glare when driving at night. Use caution when considering these glasses. Polarized night driving glasses may do more harm than good.
UV Blocking and Polarization Are Not the Same
Keep in mind that if your sunglasses are labeled as blocking the sun’s harmful ultraviolet (UV) rays, it does not mean they are polarized too. Polarized lenses will have a label saying so.
To learn more about the benefits and drawbacks of polarized lenses, talk with your eye care provider.