This is a good question. Yes, you have to have the visor down. Yes, riders have been ticketed for this. Yes, it's ridiculous, since whatever it's open is less than the opening beneath a 3/4 helmet with a face shield - like this
And yes, it's ridiculous that the manufacturer has a stay-open point made just for the purpose of defogging the visor and that NYPD disagrees.
You're supposed to have eye protection with the "ANSI Z87" standard. I believe Brad noted some inconsistencies in this law and maybe he'll chime in with more info. Check your goggles and look for an engraving.
At the end of the day, if you have "tech" looking goggles with the visor up, a cop will probably give you a pass. But legally, and safety-wise, it should be the ANSI spec ones.