Depends on what one would call protection. My prescription glasses have allowed the occasional gnat or similar insect to get by but are better than nothing. For longer rides, I feel I get better protection from my wrap around Oakley sunglasses with stick on bifocal lenses. The Oakleys are Z87 rated and are advertised to provide a degree of UV protection. I've had them for probably 10 years and the stick on bifocal lenses are cheap enough.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke