This one only has one screw and I figured there had to be clips but I can't find them and don't know how to release them

I just bought my daughter an 03 vibe. The map light is in the unit in the headliner with the switches for the moon roof. The bulb is burned out and I can't figure out how to access it. The lens doesn't have any notches that make it appear to pop out and I took the retaining screw out of the unit but...