I recall reading in Bicycling magazine about how as eyes age, it gets more difficult to distinguish light and dark areas of the road (especially in shade or when wearing sunglasses) and so as a result, hospitals see a lot 55+ riders who were injured as a result of not seeing potholes in the road. I know my vision in low light conditions is terrible these days, and I've mostly given up wearing sunglasses when driving, because subtle details are much harder to see while wearing shades (less so with high quality lenses).