I just got a motorcycle and the law here requires DOT approved eyewear if you’re on a permit like me. Does the slide-down faceshield count on my half-helmet as meeting this requirement, or do I have to get additional goggles/glasses?
You got it right. If you have a helmet with a full face-shield, this counts as approved eye protection. Al long as you keep your face-shield down.
But here is what I do to go one better.
I bought a pair of motorcycle sunglasses at a local department store. I found these at Wal-Mart for about $25. They look like ordinary sunglasses but have some handy differences.
They have foam around the edges so they act like goggles. They are polarized to prevent glare. They are photo sensitive which makes them automatically lighten or darken as needed. This is handy late in the day when the sun starts going down. They lighten enough that I don’t need to pull over to remove them. They have rubber on the pads to help make them stay on better.
I use a full face helmet with a full face-shield. However I like to raise or partially open the face-shield when I am stopped to get a little extra air. It also helps with fogging on cool mornings on my commute to work. These sunglasses give me extra protection so I don’t need to immediately lower the face-shield when I start moving again.
I don’t wear these because I have to, I wear them because I want to. When I was very young and just starting to ride motorcycles I would occasionally not wear eye protection. It didn’t take long and something hit me in the eye. Man did that hurt. It scratched the eyeball. Had to put cream in my eye and keep it covered for about a week. Luckily there was no permanent damage. But I never want this to ever happen again.