There are a lot of theories about blindness after surgery in the prone position (pressure on the eyes, low BP, etc.) but there don't appear to be enough common denominators in the cases that have been studied to point to any single cause or group of causes. It's a pretty rare complication, and the numbers aren't there to do an adequate analysis.
I think keeping pressure off the eyes and avoiding hypotension are the two biggies and also the most common sense approach, but there are reported cases where there was no hypotension noted and no pressure on the eyes.
Just a personal opinion about the goggles - I assume you're talking about the kind that stick-on to the patient. I don't like 'em. I've seen at least one patient where the plastic had gotten depressed, formed a permanent fold, and pressed against the patent's closed eye. Fortunately we noticed this prior to the start of the procedure.
For prone cases, I'd rather use a good foam headrest with adequate eye cutouts (checked frequently during the case). I've also seen them used during sitting/semi-sitting position cases like shoulder scopes. For those, I'd rather use some foam over the entire upper face (C-foams), and for all cases, remind the idiot surgeon/resident/assistant that it's the patients face, not a table, that they're resting their arm on.