It's becoming hard to find non-polarized sunglasses. Serengeti does sell non-polarized lenses, but you have to look carefully. The photochromic lenses work fairly well, not getting really light in the cockpit, and the driver gradient work very well in early and late sunlight, when the sun is low and cockpit light is rather dim. Polarized lenses are a problem with LCD displays, and if you ever expect to fly a glass cockpit, stay far away from them, because you won't be able to see any of the displays. NVG filters can make it hard to see the instruments behind them even without polarized lenses. I've never seen the point in requiring filters, because they really don't have much effect. You can't read the instruments through the NVGs anyway, because they can't focus at that distance, and you can dim the instruments enough so that they don't bother you under the goggles. Just because you have difficulty seeing through the filters doesn't necessarily mean your sunglass lenses are polarized. The green filters block a lot of the light you normally see through brown lenses.