I have trouble functioning without sunglasses.  My eyes are so extremely photosensitive that I find it painful to not wear them when it's really bright.  My eyes just squeeze shut, nothing I can do about it.  About 10 years ago I started investing in really nice sunglasses with high-quality polarized lenses, and training myself to take good enough care of them to justify the expense, because I decided I just can't take chances with my eyes....