Always wear glasses for all riding I do (7 mile town commute to all-day mtb rides).
Bike sunglasses in bright conditions, yellow most of the time and clear for night rides.
Couple of reasons … My eyes start watering quite a lot when I am over about 15mph, making it tricky to spot the trail clearly. Also stops bugs, mud, water and anything else damaging my eyes.
Made the mistake of using RainX (meant for car windscreens to aid beading and helps water get blown off the screen) on my glasses once. Don’t ride fast enough to get the beading water to blow off and also seemed to increase steam-up when it was raining and I was slowly puffing up steep climbs.