Ooh, I have vivid memories of having my eyes dilated (my dad's an ophthalmologist, so eye checkups were always after hours or weekends with just us in the office) and then having dad ask me to run real quick out to the car to grab something. On a sunny January day with several inches of snow on the ground.
I'm pretty sure the glare off the snow would have hurt my eyes even if I had been wearing sunglasses and NOT dilated, but I clearly remember how much the brightness hurt even with my eyes closed!