I've always had jobs where a lot of driving was required. When I first started driving I invested in a cool pair of $10 sunglasses from the local Chevron and thought I was smart and stylin'. Even with the darkest lenses I found myself squinting and using the vehicle sun visor on a regular basis. It would rain and then the sun would come out causing massive road glare (from the sun reflecting off the puddles) making it difficult to see at the best of times. I tried buying a $40 pair of sunglasses, thinking that they would provide better protection but I was wrong. What's the point of sunglasses if they only offer a slight visibility increase while in the sun?
Well the problem was that not only did I cheap out and buy the worst sunglasses on the market but I got the wrong type. It's absolutely imperative that if you commute or drive for a living that you invest in a decent pair of polarized sunglasses. Polarized lenses filter the glare off of almost any surface, especially snow, water and glass. You can get two different types of polarized lenses, the kind with a polarized film on the lens and the other with it in the lens. I own two pairs of Oakley polarized sunglasses and I refuse to drive without them. No more glare from windshields or puddles and they even work great when looking directly at the sun. Your eyes won't be "invincible" to the the suns intensity but they will cut it's glare and provide a greater level of colour perception. Polarized glasses can range in price but like anything, you get what you pay for. Most optometrists offer prescription or non-prescription sunglasses with options of polarized and/or transition lenses.
The images above show the difference between driving
without polarized glasses (left), and with polarized glasses (right).