As hard as it is to believe, a good polish for plastic is called... wait for it... plastic polish.
They sell this.
If you have deep scratches, you'll have to decide if it's worth the bother, to use progressively finer grits of sandpaper to get down through the depth of the scratch, before then going on with finer abrasives and then plastic polish.
A cleaner wax might be the last step, but you might also find that while it does a good final polish, that ultimately you need to strip it off with detergent because it leaves funny halo artifacts.
Clear plastic that you have to look through at close range is a special case. Personally, if I have to wear something that's been refinished, it gives me a headache if worn for more than a few minutes at a time but maybe that's just me or maybe a few minutes are all you need for certain tasks.
You don't mention what you have as far as resources, tools and materials. Although it is less than ideal, you might be able to get a fair amount of improvement with nothing more than a dremel tool with a cotton swab in it, with a lot of toothpaste on it. The deep scratches might not be worth the bother for salvage purposes. You can still polish into a deep scratch and improve it even if you don't get rid of it.
Then again, maybe just get a new pair of safety glasses and take better care of them? A lot of those I find, were scratched up as much from poor handling and storage as from work related injuries.