Like optics, buy good/quality eye protection. Now thats easier said than done as most people equate known name eyewear brands with being of good optical quality, sadly, thats not always the case.
One of the easiest ways to determine for yourself is to use a polarized lens and pass it in front of the eye pro lens. If you see "stars" or anything other than a clear lens, you are seeing the optical imperfections caused either by the poor quality lens or the deformation/forming/bending of the lens to fit in the frame creates. Often times a lens will be optically correct and clear when it is not in the frame but when they shape it to fit the frame and or place it in the frame it creates stress points in the lens which appear as little starbursts when viewed with a polarizer. These starbursts and other imperfections are imperceptible to your naked eye but you are actually having to look through these imperfections every time you put the glasses on.
One eye protection manufacturer I know of that uses optically correct glass and retains that optical clarity once the lenses are in the frame is Liquid Eyewear (
Store - Liquid Eyewear - Polarized Sunglasses ). The other added benefit is that they are ANSI Approved and offer true ballistic protection as they have met the ANSI and Mil Spec requirements for protective eyewear. Compared to what we spend on other doo-dads in shooting the cost for a pair of these glasses is not that bad and they are not only super durable, they are 100% made in the USA. I have several pairs of them and swear by them. They even do in lens RX's if you need corrective lenses.