Polarization in lenses, good or bad?
Blog vol 6.31. Polarization in lenses, good or bad?
At Burlington Eyecare, we recommend eye protection from ultraviolet (UV) light and from glare. All sunglasses are required by Canadian law to filter 100% of UVA and UVB light. This is a good thing because a sunglass reduces light to your eyes and causes your pupils to increase in size which results in 2-3 times more UV entering the eye. Protection is a must.
We looked at eye protection for winter sports, UV and glare, specifically ski goggles last week. As a rule, the filters required in the lenses will be condition dependant. Are polarized lenses helpful?
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. 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, and details are easier to see (Read more here).
Polarized lenses are great for when you are on the water or driving, so you would think that they would be perfect for skiing. However, they do have their downside —
1. When skiing, ideally you have a way of differentiating snow from ice, more difficult with polarized lenses. Ice is a lot more dangerous and to be avoided.
2. Polarized lenses reduce depth perception and contrast, making the split-second decisions in skiing or surfing more difficult to get right.
3. Skiers also rely on their peripheral vision for extra cues, not optimal with polarized lenses.
4. Golfers use glare from blades of grass to see slopes and judge greens, also affected by polarization.
5. When driving with “Heads up” displays, polarized filters make them hard to see. The same is true for LCD screens.
6. Commercial pilots work with polarized windshields on planes; an extra polarized filter in their sunglasses would be terrible.
Outside of these specific uses, polarized filters are awesome. The key is knowing what you are doing and getting polarization filters when the need arises.
Til next week,
The good doctor
