Is the glass tinted?
AFAIK anti-UV glass (or plexiglass) always has a visible tint, usually brownish. Clear glass is untreated and will let through soft UV radiation, but block out hard radiation, the type that causes skin cancer.
Can still be a problem if you sunburn easily, but on the other hand how often do you have the sun shining right on you through the windshield for a long time and not just simply diffusing into the cockpit? Diffused light is of course much less harmful than direct radiation.